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appendix J

java.lang Package Reference


CONTENTS

The java.lang package provides the core classes that make up the Java programming environment. The language package includes classes representing numbers, strings, and objects, as well as classes for handling compilation, the runtime environment, security, and threaded programming. The java.lang package is automatically imported into every Java program.

Cloneable

This interface indicates that an object may be cloned using the clone method defined in Object. The clone method clones an object by copying each of its member variables. Attempts to clone an object that doesn't implement the Cloneable interface result in a CloneNotSupportedException being thrown.

Runnable

This interface provides a means for an object to be executed within a thread without having to be derived from the Thread class. Classes implementing the Runnable interface supply a run method that defines the threaded execution for the class.

run

public abstract void run()
This method is executed when a thread associated with an object implementing the Runnable interface is started. All of the threaded execution for the object takes place in the run method, which means you should place all threaded code in this method.

Boolean

Extends: Object
This class implements an object type wrapper for boolean values. Object type wrappers are useful because many Java classes operate on objects rather than primitive data types.

Member Constants

public final static Boolean FALSE

This is a constant Boolean object representing the primitive boolean value false.

public final static Boolean TRUE

This is a constant Boolean object representing the primitive boolean value true.

Boolean Constructor

public Boolean(boolean value)
This constructor creates a boolean wrapper object representing the specified primitive boolean value.
Parameters: value-the boolean value to be wrapped.

Boolean Constructor

public Boolean(String s)
This constructor creates a boolean wrapper object representing the specified string. If the string is set to "true", the wrapper represents the primitive boolean value true; otherwise, the wrapper represents false.
Parameters: s-the string representation of a boolean value to be wrapped.

booleanValue

public boolean booleanValue()
This method determines the primitive boolean value represented by this object.
Returns: The boolean value represented.

equals

public boolean equals(Object obj)
This method compares the boolean value of the specified object to the boolean value of this object. The equals method returns true only if the specified object is a Boolean object representing the same primitive boolean value as this object.
Parameters: obj-the object to compare.
Returns: true if the specified object is a Boolean object representing the same primitive boolean value as this object; false otherwise.

getBoolean

public static boolean getBoolean(String name)
This method determines the boolean value of the system property with the specified name.
Parameters: name-the system property name to check the boolean value of.
Returns: The boolean value of the specified system property.

hashCode

public int hashCode()
This method calculates a hash code for this object.
Returns: A hash code for this object.

toString

public String toString()
This method determines a string representation of the primitive boolean value for this object. If the boolean value is true, the string "true" is returned; otherwise, the string "false" is returned.
Returns: A string representing the boolean value of this object.

valueOf

public static Boolean valueOf(String s)
This method creates a new boolean wrapper object based on the boolean value represented by the specified string. If the string is set to "true", the wrapper represents the primitive boolean value true; otherwise, the wrapper represents false.
Parameters: s-the string representation of a boolean value to be wrapped.
Returns: A boolean wrapper object representing the specified string.

Character

Extends: Object
This class implements an object type wrapper for character values. Object type wrappers are useful because many Java classes operate on objects rather than primitive data types.

Member Constants

public final static int MAX_RADIX

This is a constant representing the maximum radix value allowed for conversion between numbers and strings. This constant is set to 36.

public final static int MAX_VALUE

This is a constant representing the largest character value supported. This constant is set to '\uffff'.

public final static int MIN_RADIX

This is a constant representing the minimum radix value allowed for conversion between numbers and strings. This constant is set to 2.

public final static int MIN_VALUE

This is a constant representing the smallest character value supported. This constant is set to '\u0000'.

Character Constructor

public Character(char value)
This constructor creates a character wrapper object representing the specified primitive character value.
Parameters: value-the character value to be wrapped.

charValue

public char charValue()
This method determines the primitive character value represented by this object.
Returns: The character value represented.

digit

public static int digit(char ch, int radix)
This method determines the numeric value of the specified character digit using the specified radix.
Parameters:
ch-the character to be converted to a number.
radix-the radix to use in the conversion.
Returns: The numeric value of the specified character digit using the specified radix, or -1 if the character isn't a valid numeric digit.

equals

public boolean equals(Object obj)
This method compares the character value of the specified object to the character value of this object. The equals method returns true only if the specified object is a Character object representing the same primitive character value as this object.
Parameters: obj-the object to compare.
Returns: true if the specified object is a Character object representing the same primitive character value as this object; false otherwise.

forDigit

public static char forDigit(int digit, int radix)
This method determines the character value of the specified numeric digit using the specified radix.
Parameters:
digit-the numeric digit to be converted to a character.
radix-the radix to use in the conversion.
Returns: The character value of the specified numeric digit using the specified radix, or 0 if the number isn't a valid character.

hashCode

public int hashCode()
This method calculates a hash code for this object.
Returns: A hash code for this object.

isDefined

public static boolean isDefined(char ch)
This method determines if the specified character has a defined Unicode meaning. A character is defined if it has an entry in the Unicode attribute table.
Parameters: ch-the character to be checked.
Returns: true if the character has a defined Unicode meaning; false otherwise.

isDigit

public static boolean isDigit(char ch)
This method determines if the specified character is a numeric digit. A character is a numeric digit if its Unicode name contains the word DIGIT.
Parameters: ch-the character to be checked.
Returns: true if the character is a numeric digit; false otherwise.

isJavaLetter

public static boolean isJavaLetter(char ch)
This method determines if the specified character is permissible as the leading character in a Java identifier. A character is considered a Java letter if it is a letter, the ASCII dollar sign character ($), or the underscore character (_).
Parameters: ch-the character to be checked.
Returns: true if the character is a Java letter; false otherwise.

isJavaLetterOrDigit

public static boolean isJavaLetterOrDigit(char ch)
This method determines if the specified character is permissible as a non-leading character in a Java identifier. A character is considered a Java letter or digit if it is a letter, a digit, the ASCII dollar sign character ($), or the underscore character (_).
Parameters: ch-the character to be checked.
Returns: true if the character is a Java letter or digit; false otherwise.

isLetter

public static boolean isLetter(char ch)
This method determines if the specified character is a letter.
Parameters: ch-the character to be checked.
Returns: true if the character is a letter; false otherwise.

isLetterOrDigit

public static boolean isLetterOrDigit(char ch)
This method determines if the specified character is a letter or digit.
Parameters: ch-the character to be checked.
Returns: true if the character is a letter or digit; false otherwise.

isLowerCase

public static boolean isLowerCase(char ch)
This method determines if the specified character is a lowercase character.
Parameters: ch-the character to be checked.
Returns: true if the character is a lowercase character; false otherwise.

isSpace

public static boolean isSpace(char ch)
This method determines if the specified character is a whitespace character.
Parameters: ch-the character to be checked.
Returns: true if the character is a whitespace character; false otherwise.

isTitleCase

public static boolean isTitleCase(char ch)
This method determines if the specified character is a titlecase character. Titlecase characters are those whose printed representations look like pairs of Latin letters.
Parameters: ch-the character to be checked.
Returns: true if the character is a titlecase character; false otherwise.

isUpperCase

public static boolean isUpperCase(char ch)
This method determines if the specified character is an uppercase character.
Parameters: ch-the character to be checked.
Returns: true if the character is an uppercase character; false otherwise.

toLowerCase

public static char toLowerCase(char ch)
This method converts the specified character to a lowercase character, if the character isn't already lowercase and a lowercase equivalent exists.
Parameters: ch-the character to be converted.
Returns: The lowercase equivalent of the specified character, if one exists; otherwise, the original character.

toString

public String toString()
This method determines a string representation of the primitive character value for this object; the resulting string is one character in length.
Returns: A string representing the character value of this object.

toTitleCase

public static char toTitleCase(char ch)
This method converts the specified character to a titlecase character, if the character isn't already titlecase and a titlecase equivalent exists. Titlecase characters are those whose printed representations look like pairs of Latin letters.
Parameters: ch-the character to be converted.
Returns: The titlecase equivalent of the specified character, if one exists; otherwise, the original character.

toUpperCase

public static char toUpperCase(char ch)
This method converts the specified character to an uppercase character, if the character isn't already uppercase and an uppercase equivalent exists.
Parameters: ch-the character to be converted.
Returns: The uppercase equivalent of the specified character, if one exists; otherwise, the original character.

Class

Extends: Object
This class implements a runtime descriptor for classes and interfaces in a running Java program. Instances of Class are automatically constructed by the Java virtual machine when classes are loaded, which explains why there are no public constructors for the class.

forName

public static Class forName(String className) throws ClassNotFoundException
This method determines the runtime class descriptor for the class with the specified name.
Parameters: className-the fully qualified name of the desired class.
Returns: The runtime class descriptor for the class with the specified name.
Throws: ClassNotFoundException if the class could not be found.

getClassLoader

public ClassLoader getClassLoader()
This method determines the class loader for this object.
Returns: The class loader for this object, or null if the class wasn't created by a class loader.

getInterfaces

public Class[] getInterfaces()
This method determines the interfaces implemented by the class or interface represented by this object.
Returns: An array of interfaces implemented by the class or interface represented by this object, or an array of length 0 if no interfaces are implemented.

getName

public String getName()
This method determines the fully qualified name of the class or interface represented by this object.
Returns: The fully qualified name of the class or interface represented by this object.

getSuperclass

public Class getSuperclass()
This method determines the superclass of the class represented by this object.
Returns: The superclass of the class represented by this object, or null if this object represents the Object class.

isInterface

public boolean isInterface()
This method determines if the class represented by this object is actually an interface.
Returns: true if the class is an interface; false otherwise.

newInstance

public Object newInstance() throws InstantiationException, IllegalAccessException
This method creates a new default instance of the class represented by this object.
Returns: A new default instance of the class represented by this object.
Throws: InstantiationException if you try to instantiate an abstract class or an interface, or if the instantiation fails for some other reason.
Throws: IllegalAccessException if the class is not accessible.

toString

public String toString()
This method determines the name of the class or interface represented by this object, with the string "class" or the string "interface" prepended appropriately.
Returns: The name of the class or interface represented by this object, with a descriptive string prepended indicating whether the object represents a class or interface.

ClassLoader

Extends: Object
This class is an abstract class that defines a mechanism for dynamically loading classes into the Java runtime system.

ClassLoader Constructor

protected ClassLoader()
This constructor creates a default class loader. If a security manager is present, it is checked to see if the current thread has permission to create the class loader. If not, a SecurityException is thrown.
Throws: SecurityException if the current thread doesn't have permission to create the class loader.

defineClass

protected final Class defineClass(byte b[], int off, int len)
This method converts an array of bytes into an instance of class Class by reading len bytes from the array b beginning off bytes into the array.
Parameters:
b-the byte array containing the class data.
off-the starting offset into the array for the data.
len-the length in bytes of the class data.
Returns: A Class object created from the class data.
Throws: ClassFormatError if the class data does not define a valid class.

findSystemClass

protected final Class findSystemClass(String name) throws ClassNotFoundException
This method finds the system class with the specified name, loading it if necessary. A system class is a class loaded from the local file system with no class loader in a platform-specific manner.
Parameters: name-the name of the system class to find.
Returns: A Class object representing the system class.
Throws: ClassNotFoundException if the class is not found.
Throws: NoClassDefFoundError if a definition for the class is not found.

loadClass

protected abstract Class loadClass(String name, boolean resolve)
throws ClassNotFoundException
This method loads the class with the specified name, resolving it if the resolve parameter is set to true. This method must be implemented in all derived class loaders, because it is defined as abstract.
Parameters:
name-the name of the desired class.
resolve-a boolean value specifying whether the class is to be resolved; a value of true means the class is resolved, whereas a value of false means the class isn't resolved.
Returns: The loaded Class object, or null if the class isn't found.
Throws: ClassNotFoundException if the class is not found.

resolveClass

protected final void resolveClass(Class c)
This method resolves the specified class so that instances of it can be created or so that its methods can be called.
Parameters: c-the class to be resolved.

Compiler

Extends: Object
This class provides the framework for native Java code compilers and related services. The Java runtime system looks for a native code compiler on startup, in which case the compiler is called to compile Java bytecode classes into native code.

command

public static Object command(Object any)
This method performs some compiler-specific operation based on the type of specified object and its related state.
Parameters: any-the object to perform an operation based on.
Returns: A compiler-specific value, or null if no compiler is available.

compileClass

public static boolean compileClass(Class clazz)
This method compiles the specified class.
Parameters: clazz-the class to compile.
Returns: true if the compilation was successful, false if the compilation failed or if no compiler is available.

compileClasses

public static boolean compileClasses(String string)
This method compiles all classes whose names match the specified string name.
Parameters: string-a string containing the name of the classes to compile.
Returns: true if the compilation was successful, false if the compilation failed or if no compiler is available.

disable

public static void disable()
This method disables the compiler.

enable

public static void enable()
This method enables the compiler.

Double

Extends: Number
This class implements an object type wrapper for double values. Object type wrappers are useful because many Java classes operate on objects rather than primitive data types.

Member Constants

public final static double MAX_VALUE

This is a constant representing the maximum value allowed for a double. This constant is set to 1.79769313486231570e+308d.

public final static double MIN_VALUE

This is a constant representing the minimum value allowed for a double. This constant is set to 4.94065645841246544e-324d.

public final static double NaN

This is a constant representing the not-a-number value for double types, which is not equal to anything, including itself.

public final static double NEGATIVE_INFINITY

This is a constant representing negative infinity for double types.

public final static double POSITIVE_INFINITY

This is a constant representing positive infinity for double types.

Double Constructor

public Double(double value)
This constructor creates a double wrapper object representing the specified primitive double value.
Parameters: value-the double value to be wrapped.

Double Constructor

public Double(String s) throws NumberFormatException
This constructor creates a double wrapper object representing the specified string. The string is converted to a double using a similar technique as the valueOf method.
Parameters: s-the string representation of a double value to be wrapped.
Throws: NumberFormatException if the string does not contain a parsable double.

doubleToLongBits

public static long doubleToLongBits(double value)
This method determines the IEEE 754 floating-point double precision representation of the specified double value. The IEEE 754 floating-point double precision format specifies the following bit layout:
Parameters: value-the double value to convert to the IEEE 754 format.
Returns: The IEEE 754 floating-point representation of the specified double value.

doubleValue

public double doubleValue()
This method determines the primitive double value represented by this object.
Returns: The double value represented.

equals

public boolean equals(Object obj)
This method compares the double value of the specified object to the double value of this object. The equals method only returns true if the specified object is a Double object representing the same primitive double value as this object. Note that to be useful in hash tables, this method considers two NaN double values to be equal, even though NaN technically is not equal to itself.
Parameters: obj-the object to compare.
Returns: true if the specified object is a Double object representing the same primitive double value as this object; false otherwise.

floatValue

public float floatValue()
This method converts the primitive double value represented by this object to a float.
Returns: A float conversion of the double value represented.

hashCode

public int hashCode()
This method calculates a hash code for this object.
Returns: A hash code for this object.

intValue

public int intValue()
This method converts the primitive double value represented by this object to an integer.
Returns: An integer conversion of the double value represented.

isInfinite

public boolean isInfinite()
This method determines if the primitive double value represented by this object is positive or negative infinity.
Returns: true if the double value is positive or negative infinity; false otherwise.

isInfinite

public static boolean isInfinite(double v)
This method determines if the specified double value is positive or negative infinity.
Parameters: v-the double value to be checked.
Returns: true if the double value is positive or negative infinity; false otherwise.

isNaN

public boolean isNaN()
This method determines if the primitive double value represented by this object is not a number (NaN).
Returns: true if the double value is not a number; false otherwise.

isNaN

public static boolean isNaN(double v)
This method determines if the specified double value is not a number (NaN).
Parameters: v-the double value to be checked.
Returns: true if the double value is not a number; false otherwise.

longBitsToDouble

public static double longBitsToDouble(long bits)
This method determines the double representation of the specified IEEE 754 floating-point double precision value. The IEEE 754 floating-point double precision format specifies the following bit layout:
Parameters: bits-the IEEE 754 floating-point value to convert to a double.
Returns: The double representation of the specified IEEE 754 floating-point value.

longValue

public long longValue()
This method converts the primitive double value represented by this object to a long.
Returns: A long conversion of the double value represented.

toString

public String toString()
This method determines a string representation of the primitive double value for this object.
Returns: A string representing the double value of this object.

toString

public static String toString(double d)
This method determines a string representation of the specified double value.
Parameters: d-the double value to be converted.
Returns: A string representing the specified double value.

valueOf

public static Double valueOf(String s) throws NumberFormatException
This method creates a new double wrapper object based on the double value represented by the specified string.
Parameters: s-the string representation of a double value to be wrapped.
Returns: A double wrapper object representing the specified string.
Throws: NumberFormatException if the string does not contain a parsable double.

Float

Extends: Number
This class implements an object type wrapper for float values. Object type wrappers are useful because many Java classes operate on objects rather than primitive data types.

Member Constants

public final static float MAX_VALUE

This is a constant representing the maximum value allowed for a float. This constant is set to 3.40282346638528860e+38.

public final static float MIN_VALUE

This is a constant representing the minimum value allowed for a float. This constant is set to 1.40129846432481707e-45.

public final static float NaN

This is a constant representing the not-a-number value for float types, which is not equal to anything, including itself.

public final static float NEGATIVE_INFINITY

This is a constant representing negative infinity for float types.

public final static float POSITIVE_INFINITY

This is a constant representing positive infinity for float types.

Float Constructor

public Float(double value)
This constructor creates a float wrapper object representing the specified primitive double value.
Parameters: value-the double value to be wrapped.

Float Constructor

public Float(float value)
This constructor creates a float wrapper object representing the specified primitive float value.
Parameters: value-the float value to be wrapped.

Float Constructor

public Float(String s) throws NumberFormatException
This constructor creates a float wrapper object representing the specified string. The string is converted to a float using a similar technique as the valueOf method.
Parameters: s-the string representation of a float value to be wrapped.
Throws: NumberFormatException if the string does not contain a parsable float.

doubleValue

public double doubleValue()
This method converts the primitive float value represented by this object to a double.
Returns: A double conversion of the float value represented.

equals

public boolean equals(Object obj)
This method compares the float value of the specified object to the float value of this object. The equals method only returns true if the specified object is a Float object representing the same primitive float value as this object. Note that to be useful in hash tables, this method considers two NaN float values to be equal, even though NaN technically is not equal to itself.
Parameters: obj-the object to compare.
Returns: true if the specified object is a Float object representing the same primitive float value as this object; false otherwise.

floatToIntBits

public static int floatToIntBits(float value)
This method determines the IEEE 754 floating-point single precision representation of the specified float value. The IEEE 754 floating-point single precision format specifies the following bit layout:
Parameters: value-the float value to convert to the IEEE 754 format.
Returns: The IEEE 754 floating-point representation of the specified float value.

floatValue

public float floatValue()
This method determines the primitive float value represented by this object.
Returns: The float value represented.

hashCode

public int hashCode()
This method calculates a hash code for this object.
Returns: A hash code for this object.

intBitsToFloat

public static float intBitsToFloat(int bits)
This method determines the float representation of the specified IEEE 754 floating-point single precision value. The IEEE 754 floating-point single precision format specifies the following bit layout:
Parameters: bits-the IEEE 754 floating-point value to convert to a float.
Returns: The float representation of the specified IEEE 754 floating-point value.

intValue

public int intValue()
This method converts the primitive float value represented by this object to an integer.
Returns: An integer conversion of the float value represented.

isInfinite

public boolean isInfinite()
This method determines if the primitive float value represented by this object is positive or negative infinity.
Returns: true if the float value is positive or negative infinity; false otherwise.

isInfinite

public static boolean isInfinite(float v)
This method determines if the specified float value is positive or negative infinity.
Parameters: v-the float value to be checked.
Returns: true if the float value is positive or negative infinity; false otherwise.

isNaN

public boolean isNaN()
This method determines if the primitive float value represented by this object is not a number (NaN).
Returns: true if the float value is not a number; false otherwise.

isNaN

public static boolean isNaN(float v)
This method determines if the specified float value is not a number (NaN).
Parameters: v-the float value to be checked.
Returns: true if the float value is not a number; false otherwise.

longValue

public long longValue()
This method converts the primitive float value represented by this object to a long.
Returns: A long conversion of the float value represented.

toString

public String toString()
This method determines a string representation of the primitive float value for this object.
Returns: A string representing the float value of this object.

toString

public static String toString(float f)
This method determines a string representation of the specified float value.
Parameters: f-the float value to be converted.
Returns: A string representing the specified float value.

valueOf

public static Float valueOf(String s) throws NumberFormatException
This method creates a new float wrapper object based on the float value represented by the specified string.
Parameters: s-the string representation of a float value to be wrapped.
Returns: A float wrapper object representing the specified string.
Throws: NumberFormatException if the string does not contain a parsable float.

Integer

Extends: Number
This class implements an object type wrapper for integer values. Object type wrappers are useful because many Java classes operate on objects rather than primitive data types.

Member Constants

public final static int MAX_VALUE
This is a constant representing the maximum value allowed for an integer. This constant is set to 0x7fffffff.
public final static int MIN_VALUE
This is a constant representing the minimum value allowed for an integer. This constant is set to 0x80000000.

Integer Constructor

public Integer(int value)
This constructor creates an integer wrapper object representing the specified primitive integer value.
Parameters: value-the integer value to be wrapped.

Integer Constructor

public Integer(String s) throws NumberFormatException
This constructor creates an integer wrapper object representing the specified string. The string is converted to an integer using a similar technique as the valueOf method.
Parameters: s-the string representation of an integer value to be wrapped.
Throws: NumberFormatException if the string does not contain a parsable integer.

doubleValue

public double doubleValue()
This method converts the primitive integer value represented by this object to a double.
Returns: A double conversion of the integer value represented.

equals

public boolean equals(Object obj)
This method compares the integer value of the specified object to the integer value of this object. The equals method returns true only if the specified object is an Integer object representing the same primitive integer value as this object.
Parameters: obj-the object to compare.
Returns: true if the specified object is an Integer object representing the same primitive integer value as this object; false otherwise.

floatValue

public float floatValue()
This method converts the primitive integer value represented by this object to a float.
Returns: A float conversion of the integer value represented.

getInteger

public static Integer getInteger(String name)
This method determines an Integer object representing the value of the system property with the specified name. If the system property doesn't exist, null is returned.
Parameters: name-the system property name to check the integer value of.
Returns: An Integer object representing the value of the specified system property, or null if the property doesn't exist.

getInteger

public static Integer getInteger(String name, int val)
This method determines an Integer object representing the value of the system property with the specified name. If the system property doesn't exist, an Integer object representing the specified default property value is returned.
Parameters: name-the system property name to check the integer value of.
Parameters: val-the default integer property value.
Returns: An Integer object representing the value of the specified system property, or an Integer object representing val if the property doesn't exist.

getInteger

public static Integer getInteger(String name, Integer val)
This method determines an Integer object representing the value of the system property with the specified name. In addition, this version of getInteger includes support for reading hexadecimal and octal property values. If the system property doesn't exist, the specified default property value is returned.
Parameters:
name-the system property name to check the integer value of.
val-the default integer property value object.
Returns: An Integer object representing the value of the specified system property, or val if the property doesn't exist.

hashCode

public int hashCode()
This method calculates a hash code for this object.
Returns: A hash code for this object.

intValue

public int intValue()
This method determines the primitive integer value represented by this object.
Returns: The integer value represented.

longValue

public long longValue()
This method converts the primitive integer value represented by this object to a long.
Returns: A long conversion of the integer value represented.

parseInt

public static int parseInt(String s) throws NumberFormatException
This method parses a signed decimal integer value from the specified string. Note that all the characters in the string must be decimal digits, with the exception that the first character can be a minus character (-) to denote a negative number.
Parameters: s-the string representation of an integer value.
Returns: The integer value represented by the specified string.
Throws: NumberFormatException if the string does not contain a parsable integer.

parseInt

public static int parseInt(String s, int radix) throws NumberFormatException
This method parses a signed integer value in the specified radix from the specified string. Note that all the characters in the string must be digits in the specified radix, with the exception that the first character can be a minus character (-) to denote a negative number.
Parameters:
s-the string representation of an integer value.
radix-the radix to use for the integer.
Returns: The integer value represented by the specified string.
Throws: NumberFormatException if the string does not contain a parsable integer.

toBinaryString

public static String toBinaryString(int i)
This method determines a string representation of the specified unsigned base 2 integer value.
Parameters: i-the unsigned base 2 integer value to be converted.
Returns: A string representing the specified unsigned base 2 integer value.

toHexString

public static String toHexString(int i)
This method determines a string representation of the specified unsigned base 16 integer value.
Parameters: i-the unsigned base 16 integer value to be converted.
Returns: A string representing the specified unsigned base 16 integer value.

toOctalString

public static String toOctalString(int i)
This method determines a string representation of the specified unsigned base 8 integer value.
Parameters: i-the unsigned base 8 integer value to be converted.
Returns: A string representing the specified unsigned base 8 integer value.

toString

public String toString()
This method determines a string representation of the primitive decimal integer value for this object.
Returns: A string representing the decimal integer value of this object.

toString

public static String toString(int i)
This method determines a string representation of the specified decimal integer value.
Parameters: i-the decimal integer value to be converted.
Returns: A string representing the specified decimal integer value.

toString

public static String toString(int i, int radix)
This method determines a string representation of the specified integer value in the specified radix.
Parameters:
i-the integer value to be converted.
radix-the radix to use for the conversion.
Returns: A string representing the specified integer value in the specified radix.

valueOf

public static Integer valueOf(String s) throws NumberFormatException
This method creates a new integer wrapper object based on the decimal integer value represented by the specified string.
Parameters: s-the string representation of a decimal integer value to be wrapped.
Returns: An integer wrapper object representing the specified string.
Throws: NumberFormatException if the string does not contain a parsable integer.

valueOf

public static Integer valueOf(String s, int radix) throws NumberFormatException
This method creates a new integer wrapper object based on the integer value in the specified radix represented by the specified string.
Parameters:
s-the string representation of an integer value to be wrapped.
radix-the radix to use for the integer.
Returns: An integer wrapper object in the specified radix representing the specified string.
Throws: NumberFormatException if the string does not contain a parsable integer.

Long

Extends: Number
This class implements an object type wrapper for long values. Object type wrappers are useful because many Java classes operate on objects rather than primitive data types.

Member Constants

public final static int MAX_VALUE

This is a constant representing the maximum value allowed for a long. This constant is set to 0x7fffffffffffffff.

public final static int MIN_VALUE

This is a constant representing the minimum value allowed for a long. This constant is set to 0x8000000000000000.

Long Constructor

public Long(long value)
This constructor creates a long wrapper object representing the specified primitive long value.
Parameters: value-the long value to be wrapped.

Long Constructor

public Long(String s) throws NumberFormatException
This constructor creates a long wrapper object representing the specified string. The string is converted to a long using a similar technique as the valueOf method.
Parameters: s-the string representation of a long value to be wrapped.
Throws: NumberFormatException if the string does not contain a parsable long.

doubleValue

public double doubleValue()
This method converts the primitive long value represented by this object to a double.
Returns: A double conversion of the long value represented.

equals

public boolean equals(Object obj)
This method compares the long value of the specified object to the long value of this object. The equals method returns true only if the specified object is a Long object representing the same primitive long value as this object.
Parameters: obj-the object to compare.
Returns: true if the specified object is a Long object representing the same primitive long value as this object; false otherwise.

floatValue

public float floatValue()
This method converts the primitive long value represented by this object to a float.
Returns: A float conversion of the long value represented.

getLong

public static Long getLong(String name)
This method determines a Long object representing the value of the system property with the specified name. If the system property doesn't exist, null is returned.
Parameters: name-the system property name to check the long value of.
Returns: A Long object representing the value of the specified system property, or null if the property doesn't exist.

getLong

public static Long getLong(String name, long val)
This method determines a Long object representing the value of the system property with the specified name. If the system property doesn't exist, a Long object representing the specified default property value is returned.
Parameters: name-the system property name to check the long value of.
Parameters: val-the default long property value.
Returns: A Long object representing the value of the specified system property, or a long object representing val if the property doesn't exist.

getLong

public static Long getLong(String name, Long val)
This method determines a Long object representing the value of the system property with the specified name. In addition, this version of getLong includes support for reading hexadecimal and octal property values. If the system property doesn't exist, the specified default property value is returned.
Parameters:
name-the system property name to check the long value of.
val-the default long property value object.
Returns: A Long object representing the value of the specified system property, or val if the property doesn't exist.

hashCode

public int hashCode()
This method calculates a hash code for this object.
Returns: A hash code for this object.

intValue

public int intValue()
This method converts the primitive long value represented by this object to an integer.
Returns: An integer conversion of the long value represented.

longValue

public long longValue()
This method determines the primitive long value represented by this object.
Returns: The long value represented.

parseLong

public static long parseLong(String s) throws NumberFormatException
This method parses a signed decimal long value from the specified string. Note that all the characters in the string must be decimal digits, with the exception that the first character can be a minus character (-) to denote a negative number.
Parameters: s-the string representation of a long value.
Returns: The long value represented by the specified string.
Throws: NumberFormatException if the string does not contain a parsable long.

parseLong

public static long parseLong(String s, int radix) throws NumberFormatException
This method parses a signed long value in the specified radix from the specified string. Note that all the characters in the string must be digits in the specified radix, with the exception that the first character can be a minus character (-) to denote a negative number.
Parameters:
s-the string representation of a long value.
radix-the radix to use for the long.
Returns: The long value represented by the specified string.
Throws: NumberFormatException if the string does not contain a parsable long.

toBinaryString

public static String toBinaryString(long l)
This method determines a string representation of the specified unsigned base 2 long value.
Parameters: l-the unsigned base 2 long value to be converted.
Returns: A string representing the specified unsigned base 2 long value.

toHexString

public static String toHexString(long l)
This method determines a string representation of the specified unsigned base 16 long value.
Parameters: l-the unsigned base 16 long value to be converted.
Returns: A string representing the specified unsigned base 16 long value.

toOctalString

public static String toOctalString(long l)
This method determines a string representation of the specified unsigned base 8 long value.
Parameters: l-the unsigned base 8 long value to be converted.
Returns: A string representing the specified unsigned base 8 long value.

toString

public String toString()
This method determines a string representation of the primitive decimal long value for this object.
Returns: A string representing the decimal long value of this object.

toString

public static String toString(long l)
This method determines a string representation of the specified decimal long value.
Parameters: l-the decimal long value to be converted.
Returns: A string representing the specified decimal long value.

toString

public static String toString(long l, int radix)
This method determines a string representation of the specified long value in the specified radix.
Parameters:
i-the long value to be converted.
radix-the radix to use for the conversion.
Returns: A string representing the specified long value in the specified radix.

valueOf

public static Long valueOf(String s) throws NumberFormatException
This method creates a new long wrapper object based on the decimal long value represented by the specified string.
Parameters: s-the string representation of a decimal long value to be wrapped.
Returns: A long wrapper object representing the specified string.
Throws: NumberFormatException if the string does not contain a parsable long.

valueOf

public static Long valueOf(String s, int radix) throws NumberFormatException
This method creates a new long wrapper object based on the long value in the specified radix represented by the specified string.
Parameters:
s-the string representation of a long value to be wrapped.
radix-the radix to use for the long.
Returns: A long wrapper object in the specified radix representing the specified string.
Throws: NumberFormatException if the string does not contain a parsable long.

Math

Extends: Object
This class implements a library of common math functions, including methods for performing basic numerical operations such as elementary exponential, logarithm, square root, and trigonometric functions.

Member Constants

public final static double E

This is a constant representing the double value of E, which is the base of the natural logarithms. This constant is set to 2.7182818284590452354.

public final static double PI

This is a constant representing the double value of PI, which is the ratio of the circumference of a circle to its diameter. This constant is set to 3.14159265358979323846.

abs

public static double abs(double a)
This method calculates the absolute value of the specified double value.
Parameters: a-the double value to calculate the absolute value of.
Returns: The absolute value of the double value.

abs

public static float abs(float a)
This method calculates the absolute value of the specified float value.
Parameters: a-the float value to calculate the absolute value of.
Returns: The absolute value of the float value.

abs

public static int abs(int a)
This method calculates the absolute value of the specified integer value.
Parameters: a-the integer value to calculate the absolute value of.
Returns: The absolute value of the integer value.

abs

public static long abs(long a)
This method calculates the absolute value of the specified long value.
Parameters: a-the long value to calculate the absolute value of.
Returns: The absolute value of the long value.

acos

public static double acos(double a)
This method calculates the arc cosine of the specified double value.
Parameters: a-the double value to calculate the arc cosine of.
Returns: The arc cosine of the double value.

asin

public static double asin(double a)
This method calculates the arc sine of the specified double value.
Parameters: a-the double value to calculate the arc sine of.
Returns: The arc sine of the double value.

atan

public static double atan(double a)
This method calculates the arc tangent of the specified double value.
Parameters: a-the double value to calculate the arc tangent of.
Returns: The arc tangent of the double value.

atan2

public static double atan2(double x, double y)
This method calculates the theta component of the polar coordinate (r,theta) corresponding to the rectangular coordinate (x y) specified by the double values.
Parameters:
x-the x component value of the rectangular coordinate.
y-the y component value of the rectangular coordinate.
Returns: The theta component of the polar coordinate corresponding to the rectangular coordinate specified by the double values.

ceil

public static double ceil(double a)
This method determines the smallest double whole number that is greater than or equal to the specified double value.
Parameters: a-the double value to calculate the ceiling of.
Returns: The smallest double whole number that is greater than or equal to the specified double value.

cos

public static double cos(double a)
This method calculates the cosine of the specified double value, which is specified in radians.
Parameters: a-the double value to calculate the cosine of, in radians.
Returns: The cosine of the double value.

exp

public static double exp(double a)
This method calculates the exponential value of the specified double value, which is E raised to the power of a.
Parameters: a-the double value to calculate the exponential value of.
Returns: The exponential value of the specified double value.

floor

public static double floor(double a)
This method determines the largest double whole number that is less than or equal to the specified double value.
Parameters: a-the double value to calculate the floor of.
Returns: The largest double whole number that is less than or equal to the specified double value.

IEEEremainder

public static double IEEEremainder(double f1, double f2)
This method calculates the remainder of f1 divided by f2 as defined by the IEEE 754 standard.
Parameters:
f1-the dividend for the division operation.
f2-the divisor for the division operation.
Returns: The remainder of f1 divided by f2 as defined by the IEEE 754 standard.

log

public static double log(double a) throws ArithmeticException
This method calculates the natural logarithm (base E) of the specified double value.
Parameters: a-the double value, which is greater than 0.0, to calculate the natural logarithm of.
Returns: The natural logarithm of the specified double value.
Throws: ArithmeticException if the specified double value is less than 0.0.

max

public static double max(double a, double b)
This method determines the larger of the two specified double values.
Parameters:
a-the first double value to be compared.
b-the second double value to be compared.
Returns: The larger of the two specified double values.

max

public static float max(float a, float b)
This method determines the larger of the two specified float values.
Parameters:
a-the first float value to be compared.
b-the second float value to be compared.
Returns: The larger of the two specified float values.

max

public static int max(int a, int b)
This method determines the larger of the two specified integer values.
Parameters:
a-the first integer value to be compared.
b-the second integer value to be compared.
Returns: The larger of the two specified integer values.

max

public static long max(long a, long b)
This method determines the larger of the two specified long values.
Parameters:
a-the first long value to be compared.
b-the second long value to be compared.
Returns: The larger of the two specified long values.

min

public static double min(double a, double b)
This method determines the smaller of the two specified double values.
Parameters:
a-the first double value to be compared.
b-the second double value to be compared.
Returns: The smaller of the two specified double values.

min

public static float min(float a, float b)
This method determines the smaller of the two specified float values.
Parameters:
a-the first float value to be compared.
b-the second float value to be compared.
Returns: The smaller of the two specified float values.

min

public static int min(int a, int b)
This method determines the smaller of the two specified integer values.
Parameters:
a-the first integer value to be compared.
b-the second integer value to be compared.
Returns: The smaller of the two specified integer values.

min

public static long min(long a, long b)
This method determines the smaller of the two specified long values.
Parameters:
a-the first long value to be compared.
b-the second long value to be compared.
Returns: The smaller of the two specified long values.

pow

public static double pow(double a, double b) throws ArithmeticException
This method calculates the double value a raised to the power of b.
Parameters:
a-a double value to be raised to a power specified by b.
b-the power to raise a to.
Returns: The double value a raised to the power of b.
Throws: ArithmeticException if a equals 0.0 and b is less than or equal to 0.0, or if a is less than or equal to 0.0 and b is not a whole number.

random

public static double random()
This method generates a pseudo-random double between 0.0 and 1.0.
Returns: A pseudo-random double between 0.0 and 1.0.

rint

public static double rint(double a)
This method determines the closest whole number to the specified double value. If the double value is equally spaced between two whole numbers, rint will return the even number.
Parameters: a-the double value to determine the closest whole number.
Returns: The closest whole number to the specified double value.

round

public static long round(double a)
This method rounds off the specified double value by determining the closest long value.
Parameters: a-the double value to round off.
Returns: The closest long value to the specified double value.

round

public static int round(float a)
This method rounds off the specified float value by determining the closest integer value.
Parameters: a-the float value to round off.
Returns: The closest integer value to the specified float value.

sin

public static double sin(double a)
This method calculates the sine of the specified double value, which is specified in radians.
Parameters: a-the double value to calculate the sine of, in radians.
Returns: The sine of the double value.

sqrt

public static double sqrt(double a) throws ArithmeticException
This method calculates the square root of the specified double value.
Parameters: a-the double value, which is greater than 0.0, to calculate the square root for.
Returns: The square root of the double value.
Throws: ArithmeticException if the specified double value is less than 0.0.

tan

public static double tan(double a)
This method calculates the tangent of the specified double value, which is specified in radians.
Parameters: a-the double value to calculate the tangent of, in radians.
Returns: The tangent of the double value.

Number

Extends: Object
This class is an abstract class that provides the basic functionality required of a numeric object. All specific numeric objects are derived from Number.

doubleValue

public abstract double doubleValue()
This method determines the primitive double value represented by this object. Note that this may involve rounding if the number is not already a double.
Returns: The double value represented.

floatValue

public abstract float floatValue()
This method determines the primitive float value represented by this object. Note that this may involve rounding if the number is not already a float.
Returns: The float value represented.

intValue

public abstract int intValue()
This method determines the primitive integer value represented by this object.
Returns: The integer value represented.

longValue

public abstract long longValue()
This method determines the primitive long value represented by this object.
Returns: The long value represented.

Object

This class is the root of the Java class hierarchy, providing the core functionality required of all objects. All classes have Object as a superclass, and all classes implement the methods defined in Object.

Object Constructor

public Object()
This constructor creates a default object.

clone

protected Object clone() throws CloneNotSupportedException
This method creates a clone of this object by creating a new instance of the class and copying each of the member variables of this object to the new object. To be cloneable, derived classes must implement the Cloneable interface.
Returns: A clone of this object.
Throws: OutOfMemoryError if there is not enough memory.
Throws: CloneNotSupportedException if the object doesn't support the Cloneable interface or if it explicitly doesn't want to be cloned.

equals

public boolean equals(Object obj)
This method compares this object with the specified object for equality. The equals method is used by the Hashtable class to compare objects stored in the hash table.
Parameters: obj-the object to compare.
Returns: true if this object is equivalent to the specified object; false otherwise.

finalize

protected void finalize() throws Throwable
This method is called by the Java garbage collector when an object is being destroyed. The default behavior of finalize is to do nothing. Derived classes can override finalize to include cleanup code that is to be executed when the object is destroyed.

getClass

public final Class getClass()
This method determines the runtime class descriptor for this object.
Returns: The runtime class descriptor for this object.

hashCode

public int hashCode()
This method calculates a hash code for this object, which is a unique integer identifying the object. Hash codes are used by the Hashtable class.
Returns: A hash code for this object.

notify

public final void notify()
This method wakes up a single thread that is waiting on this object's monitor. A thread is set to wait on an object's monitor when the wait method is called. The notify method should only be called by a thread that is the owner of this object's monitor. Note that the notify method can only be called from within a synchronized method.
Throws: IllegalMonitorStateException if the current thread is not the owner of this object's monitor.

notifyAll

public final void notifyAll()
This method wakes up all threads that are waiting on this object's monitor. A thread is set to wait on an object's monitor when the wait method is called. The notifyAll method should only be called by a thread that is the owner of this object's monitor. Note that the notifyAll method can only be called from within a synchronized method.
Throws: IllegalMonitorStateException if the current thread is not the owner of this object's monitor.

toString

public String toString()
This method determines a string representation of this object. It is recommended that all derived classes override toString.
Returns: A string representing this object.

wait

public final void wait() throws InterruptedException
This method causes the current thread to wait forever until it is notified via a call to the notify or notifyAll methods. The wait method should only be called by a thread that is the owner of this object's monitor. Note that the wait method can only be called from within a synchronized method.
Throws: IllegalMonitorStateException if the current thread is not the owner of this object's monitor.
Throws: InterruptedException if another thread has interrupted this thread.

wait

public final void wait(long timeout) throws InterruptedException
This method causes the current thread to wait until it is notified via a call to the notify or notifyAll method, or until the specified timeout period has elapsed. The wait method should only be called by a thread that is the owner of this object's monitor. Note that the wait method can only be called from within a synchronized method.
Parameters: timeout-the maximum timeout period to wait, in milliseconds.
Throws: IllegalMonitorStateException if the current thread is not the owner of this object's monitor.
Throws: InterruptedException if another thread has interrupted this thread.

wait

public final void wait(long timeout, int nanos) throws InterruptedException
This method causes the current thread to wait until it is notified via a call to the notify or notifyAll method, or until the specified timeout period has elapsed. The timeout period in this case is the addition of the timeout and nanos parameters, which provide finer control over the timeout period. The wait method should only be called by a thread that is the owner of this object's monitor. Note that the wait method can only be called from within a synchronized method.
Parameters:
timeout-the maximum timeout period to wait, in milliseconds.
nanos-the additional time for the timeout period, in nanoseconds.
Throws: IllegalMonitorStateException if the current thread is not the owner of this object's monitor.
Throws: InterruptedException if another thread has interrupted this thread.

Process

Extends: Object
This class is an abstract class that provides the basic functionality required of a system process. Derived Process objects (subprocesses) are returned from the exec methods defined in the Runtime class.

Process Constructor

public Process()
This constructor creates a default process.

destroy

public abstract void destroy()
This method kills the subprocess.

exitValue

public abstract int exitValue()
This method determines the exit value of the subprocess.
Returns: The integer exit value for the subprocess.
Throws: IllegalThreadStateException if the subprocess has not yet terminated.

getErrorStream

public abstract InputStream getErrorStream()
This method determines the error stream associated with the subprocess.
Returns: The error stream associated with the subprocess.

getInputStream

public abstract InputStream getInputStream()
This method determines the input stream associated with the subprocess.
Returns: The input stream associated with the subprocess.

getOutputStream

public abstract OutputStream getOutputStream()
This method determines the output stream associated with the subprocess.
Returns: The output stream associated with the subprocess.

waitFor

public abstract int waitFor() throws InterruptedException
This method waits for the subprocess to finish executing. When the subprocess finishes executing, the integer exit value is returned.
Returns: The integer exit value for the subprocess.
Throws: InterruptedException if another thread has interrupted this thread.

Runtime

Extends: Object
This class provides a mechanism for interacting with the Java runtime environment. Each running Java application has access to a single instance of the Runtime class, which it can use to query and modify the runtime environment.

exec

public Process exec(String command) throws IOException
This method executes the system command represented by the specified string in a separate subprocess.
Parameters: command-a string representing the system command to execute.
Returns: The subprocess that is executing the system command.
Throws: SecurityException if the current thread cannot create the subprocess.

exec

public Process exec(String command, String envp[]) throws IOException
This method executes the system command represented by the specified string in a separate subprocess with the specified environment.
Parameters:
command-a string representing the system command to execute.
envp-an array of strings representing the environment.
Returns: The subprocess that is executing the system command.
Throws: SecurityException if the current thread cannot create the subprocess.

exec

public Process exec(String cmdarray[]) throws IOException
This method executes the system command with arguments represented by the specified string array in a separate subprocess.
Parameters: cmdarray-an array of strings representing the system command to execute along with its arguments.
Returns: The subprocess that is executing the system command.
Throws: SecurityException if the current thread cannot create the subprocess.

exec

public Process exec(String cmdarray[], String envp[]) throws IOException
This method executes the system command with arguments represented by the specified string array in a separate subprocess with the specified environment.
Parameters:
cmdarray-an array of strings representing the system command to execute along with its arguments.
envp-an array of strings representing the environment.
Returns: The subprocess that is executing the system command.
Throws: SecurityException if the current thread cannot create the subprocess.

exit

public void exit(int status)
This method exits the Java runtime system (virtual machine) with the specified integer exit status. Note that since exit kills the runtime system, it never returns.
Parameters: status-the integer exit status; this should be set to nonzero if this is an abnormal exit.
Throws: SecurityException if the current thread cannot exit with the specified exit status.

freeMemory

public long freeMemory()
This method determines the approximate amount of free memory available in the runtime system, in bytes.
Returns: Approximate amount of free memory available, in bytes.

gc

public void gc()
This method invokes the Java garbage collector to clean up any objects that are no longer needed, usually resulting in more free memory.

getLocalizedInputStream

public InputStream getLocalizedInputStream(InputStream in)
This method creates a localized input stream based on the specified input stream. A localized input stream is a stream whose local characters are mapped to Unicode characters as they are read.
Parameters: in-the input stream to localize.
Returns: A localized input stream based on the specified input stream.

getLocalizedOutputStream

public OutputStream getLocalizedOutputStream(OutputStream out)
This method creates a localized output stream based on the specified output stream. A localized output stream is a stream whose Unicode characters are mapped to local characters as they are written.
Parameters: out-the output stream to localize.
Returns: A localized output stream based on the specified output stream.

getRuntime

public static Runtime getRuntime()
This method gets the runtime environment object associated with the current Java program.
Returns: The runtime environment object associated with the current Java program.

load

public void load(String pathname)
This method loads the dynamic library with the specified complete pathname.
Parameters: pathname-the path name of the library to load.
Throws: UnsatisfiedLinkError if the library doesn't exist.
Throws: SecurityException if the current thread can't load the library.

loadLibrary

public void loadLibrary(String libname)
This method loads the dynamic library with the specified library name. Note that the mapping from library name to a specific filename is performed in a platform-specific manner.
Parameters: libname-the name of the library to load.
Throws: UnsatisfiedLinkError if the library doesn't exist.
Throws: SecurityException if the current thread can't load the library.

runFinalization

public void runFinalization()
This method explicitly causes the finalize methods of any discarded objects to be called.

totalMemory

public long totalMemory()
This method determines the total amount of memory in the runtime system, in bytes.
Returns: The total amount of memory, in bytes.

traceInstructions

public void traceInstructions(boolean on)
This method is used to determine whether the Java virtual machine prints out a detailed trace of each instruction executed.
Parameters: on-a boolean value specifying whether the Java virtual machine prints out a detailed trace of each instruction executed; a value of true means the instruction trace is printed, whereas a value of false means the instruction trace isn't printed.

traceMethodCalls

public void traceMethodCalls(boolean on)
This method is used to determine whether the Java virtual machine prints out a detailed trace of each method that is called.
Parameters: on-a boolean value specifying whether the Java virtual machine prints out a detailed trace of each method that is called; a value of true means the method call trace is printed, whereas a value of false means the method call trace isn't printed.

SecurityManager

Extends: Object
This class is an abstract class that defines a security policy that can be used by Java programs to check for potentially unsafe operations.

Member Variables

protected boolean inCheck
This member variable specifies whether a security check is in progress. A value of true indicates that a security check is in progress, where a value of false means no check is taking place.

SecurityManager Constructor

protected SecurityManager()
This constructor creates a default security manager. Note that only one security manager is allowed for each Java program.
Throws: SecurityException if the security manager cannot be created.

checkAccept

public void checkAccept(String host, int port)
This method checks to see if the calling thread is allowed to establish a socket connection to the specified port on the specified host.
Parameters:
host-the host name to connect the socket to.
port-the number of the port to connect the socket to.
Throws: SecurityException if the calling thread doesn't have permission to establish the socket connection.

checkAccess

public void checkAccess(Thread g)
This method checks to see if the calling thread is allowed access to the specified thread.
Parameters: g-the thread to check for access.
Throws: SecurityException if the calling thread doesn't have access to the specified thread.

checkAccess

public void checkAccess(ThreadGroup g)
This method checks to see if the calling thread is allowed access to the specified thread group.
Parameters: g-the thread group to check for access.
Throws: SecurityException if the calling thread doesn't have access to the specified thread group.

checkConnect

public void checkConnect(String host, int port)
This method checks to see if the calling thread has established a socket connection to the specified port on the specified host.
Parameters:
host-the host name to check the connection for.
port-the number of the port to check the connection for.
Throws: SecurityException if the calling thread doesn't have permission to establish the socket connection.

checkConnect

public void checkConnect(String host, int port, Object context)
This method checks to see if the specified security context has established a socket connection to the specified port on the specified host.
Parameters:
host-the host name to check the connection for.
port-the number of the port to check the connection for.
context-the security context for the check.
Throws: SecurityException if the specified security context doesn't have permission to establish the socket connection.

checkCreateClassLoader

public void checkCreateClassLoader()
This method checks to see if the calling thread is allowed access to create a new class loader.
Throws: SecurityException if the calling thread doesn't have permission to create a new class loader.

checkDelete

public void checkDelete(String file)
This method checks to see if the calling thread is allowed access to delete the file with the specified platform-specific filename.
Parameters: file-the platform-specific filename for the file to be checked.
Throws: SecurityException if the calling thread doesn't have permission to delete the file.

checkExec

public void checkExec(String cmd)
This method checks to see if the calling thread is allowed access to create a subprocess to execute the specified system command.
Parameters: cmd-a string representing the system command to be checked.
Throws: SecurityException if the calling thread doesn't have permission to create a subprocess to execute the system command.

checkExit

public void checkExit(int status)
This method checks to see if the calling thread is allowed access to exit the Java runtime system with the specified exit status.
Parameters: status-the integer exit status to be checked.
Throws: SecurityException if the calling thread doesn't have permission to exit with the specified exit status.

checkLink

public void checkLink(String libname)
This method checks to see if the calling thread is allowed access to dynamically link the library with the specified name.
Parameters: libname-the name of the library to be checked.
Throws: SecurityException if the calling thread doesn't have permission to dynamically link the library.

checkListen

public void checkListen(int port)
This method checks to see if the calling thread is allowed to wait for a connection request on the specified port.
Parameters: port-the number of the port to check the connection for.
Throws: SecurityException if the calling thread doesn't have permission to wait for a connection request on the specified port.

checkPackageAccess

public void checkPackageAccess(String pkg)
This method checks to see if the calling thread is allowed access to the package with the specified name.
Parameters: pkg-the name of the package to be checked.
Throws: SecurityException if the calling thread doesn't have permission to access the package.

checkPackageDefinition

public void checkPackageDefinition(String pkg)
This method checks to see if the calling thread is allowed to define classes in the package with the specified name.
Parameters: pkg-the name of the package to be checked.
Throws: SecurityException if the calling thread doesn't have permission to define classes in the package.

checkPropertiesAccess

public void checkPropertiesAccess()
This method checks to see if the calling thread is allowed access to the system properties.
Throws: SecurityException if the calling thread doesn't have permission to access the system properties.

checkPropertyAccess

public void checkPropertyAccess(String key)
This method checks to see if the calling thread is allowed access to the system property with the specified key name.
Parameters: key-the key name for the system property to check.
Throws: SecurityException if the calling thread doesn't have permission to access the system property with the specified key name.

checkRead

public void checkRead(FileDescriptor fd)
This method checks to see if the calling thread is allowed access to read from the file with the specified file descriptor.
Parameters: fd-the file descriptor for the file to be checked.
Throws: SecurityException if the calling thread doesn't have permission to read from the file.

checkRead

public void checkRead(String filename)
This method checks to see if the calling thread is allowed access to read from the file with the specified platform-specific filename.
Parameters: file-the platform-specific filename for the file to be checked.
Throws: SecurityException if the calling thread doesn't have permission to read from the file.

checkRead

public void checkRead(String file, Object context)
This method checks to see if the specified security context is allowed access to read from the file with the specified platform-specific filename.
Parameters:
file-the platform-specific filename for the file to be checked.
context-the security context for the check.
Throws: SecurityException if the specified security context doesn't have permission to read from the file.

checkSetFactory

public void checkSetFactory()
This method checks to see if the calling thread is allowed access to set the socket or stream handler factory used by the URL class.
Throws: SecurityException if the calling thread doesn't have permission to set the socket or stream handler factory.

checkTopLevelWindow

public boolean checkTopLevelWindow(Object window)
This method checks to see if the calling thread is trusted to show the specified top-level window.
Parameters: window-the top-level window to be checked.
Returns: true if the calling thread is trusted to show the top-level window; false otherwise.

checkWrite

public void checkWrite(FileDescriptor fd)
This method checks to see if the calling thread is allowed access to write to the file with the specified file descriptor.
Parameters: fd-the file descriptor for the file to be checked.
Throws: SecurityException if the calling thread doesn't have permission to write to the file.

checkWrite

public void checkWrite(String file)
This method checks to see if the calling thread is allowed access to write to the file with the specified platform-specific filename.
Parameters: file-the platform-specific filename for the file to be checked.
Throws: SecurityException if the calling thread doesn't have permission to write to the file.

classDepth

protected int classDepth(String name)
This method determines the stack depth of the class with the specified name.
Parameters: name-the fully qualified name of the class to determine the stack depth of.
Returns: The stack depth of the class, or -1 if the class can't be found in any stack frame.

classLoaderDepth

protected int classLoaderDepth()
This method determines the stack depth of the most recently executing method of a class defined using a class loader.
Returns: The stack depth of the most recently executing method of a class defined using a class loader, or -1 if no method is executing within a class defined by a class loader.

currentClassLoader

protected ClassLoader currentClassLoader()
This method determines the current class loader on the stack.
Returns: The current class loader on the stack, or null if no class loader exists on the stack.

getClassContext

protected Class[] getClassContext()
This method determines the current execution stack, which is an array of classes corresponding to each method call on the stack.
Returns: An array of classes corresponding to each method call on the stack.

getInCheck

public boolean getInCheck()
This method determines whether there is a security check in progress.
Returns: true if a security check is in progress; false otherwise.

getSecurityContext

public Object getSecurityContext()
This method creates a platform-specific security context based on the current runtime environment.
Returns: A platform-specific security context based on the current runtime environment.

inClass

protected boolean inClass(String name)
This method determines if a method in the class with the specified name is on the execution stack.
Parameters: name-the name of the class to check.
Returns: true if a method in the class is on the execution stack; false otherwise.

inClassLoader

protected boolean inClassLoader()
This method determines if a method in a class defined using a class loader is on the execution stack.
Returns: true if a method in a class defined using a class loader is on the execution stack; false otherwise.

String

Extends: Object
This class implements a constant string of characters. The String class provides a wide range of support for working with strings of characters. Note that literal string constants are automatically converted to String objects by the Java compiler.

String Constructor

public String()
This constructor creates a default string containing no characters.

String Constructor

public String(byte ascii[], int hibyte)
This constructor creates a string from the specified array of bytes, with the top 8 bits of each string character set to hibyte.
Parameters:
ascii-the byte array that is to be converted to string characters.
hibyte-the high byte value for each character.

String Constructor

public String(byte ascii[], int hibyte, int off, int count)
This constructor creates a string of length count from the specified array of bytes beginning off bytes into the array, with the top 8 bits of each string character set to hibyte.
Parameters:
ascii-the byte array that is to be converted to string characters.
hibyte-the high byte value for each character.
off-the starting offset into the array of bytes.
count-the number of bytes from the array to convert.
Throws: StringIndexOutOfBoundsException if the offset or count for the byte array is invalid.

String Constructor

public String(char value[])
This constructor creates a string from the specified array of characters.
Parameters: value-the character array to initialize the string with.

String Constructor

public String(char value[], int off, int count)
This constructor creates a string of length count from the specified array of characters beginning off bytes into the array.
Parameters:
value-the character array to initialize the string with.
off-the starting offset into the array of characters.
count-the number of characters from the array to use in initializing the string.
Throws: StringIndexOutOfBoundsException if the offset or count for the character array is invalid.

String Constructor

public String(String value)
This method creates a new string that is a copy of the specified string.
Parameters: value-the string to initialize this string with.

String Constructor

public String(StringBuffer buffer)
This method creates a new string that is a copy of the contents of the specified string buffer.
Parameters: buffer-the string buffer to initialize this string with.

charAt

public char charAt(int index)
This method determines the character at the specified index. Note that string indexes are zero based, meaning that the first character is located at index 0.
Parameters: index-the index of the desired character.
Returns: The character at the specified index.
Throws: StringIndexOutOfBoundsException if the index is out of range.

compareTo

public int compareTo(String anotherString)
This method compares this string with the specified string lexicographically.
Parameters: anotherString-the string to be compared with.
Returns: If this string is equal to the specified string, a value less than 0 if this string is lexicographically less than the specified string, or a value greater than 0 if this string is lexicographically greater than the specified string.

concat

public String concat(String str)
This method concatenates the specified string onto the end of this string.
Parameters: str-the string to concatenate.
Returns: This string, with the specified string concatenated onto the end.

copyValueOf

public static String copyValueOf(char data[])
This method converts a character array to an equivalent string by creating a new string and copying the characters into it.
Parameters: data-the character array to convert to a string.
Returns: A string representation of the specified character array.

copyValueOf

public static String copyValueOf(char data[], int off, int count)
This method converts a character array to an equivalent string by creating a new string and copying count characters into it beginning at off.
Parameters:
data-the character array to convert to a string.
off-the starting offset into the character array.
count-the number of characters from the array to use in initializing the string.
Returns: A string representation of the specified character array beginning at off and of length count.

endsWith

public boolean endsWith(String suffix)
This method determines whether this string ends with the specified suffix.
Parameters: suffix-the suffix to check.
Returns: true if this string ends with the specified suffix; false otherwise.

equals

public boolean equals(Object obj)
This method compares the specified object to this string. The equals method returns true only if the specified object is a String object of the same length and contains the same characters as this string.
Parameters: obj-the object to compare.
Returns: true if the specified object is a String object of the same length and contains the same characters as this string; false otherwise.

equalsIgnoreCase

public boolean equalsIgnoreCase(String anotherString)
This method compares the specified string to this string, ignoring case.
Parameters: anotherString-the string to compare.
Returns: true if the specified string is of the same length and contains the same characters as this string, ignoring case; false otherwise.

getBytes

public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin)
This method copies the lower 8 bits of each character in this string beginning at srcBegin and ending at srcEnd into the byte array dst beginning at dstBegin.
Parameters:
srcBegin-index of the first character in the string to copy.
srcEnd-index of the last character in the string to copy.
dst-the destination byte array.
dstBegin-the starting offset into the byte array.

getChars

public void getChars(int srcBegin, int srcEnd, char
dst[], int dstBegin)
This method copies each character in this string beginning at srcBegin and ending at srcEnd into the character array dst beginning at dstBegin.
Parameters:
srcBegin-index of the first character in the string to copy.
srcEnd-index of the last character in the string to copy.
dst-the destination character array.
dstBegin-the starting offset into the character array.
Throws: StringIndexOutOfBoundsException if there is an invalid index into the buffer.

hashCode

public int hashCode()
This method calculates a hash code for this object.
Returns: A hash code for this object.

indexOf

public int indexOf(int ch)
This method determines the index of the first occurrence of the specified character in this string.
Parameters: ch-the character to search for.
Returns: The index of the first occurrence of the specified character, or -1 if the character doesn't occur.

indexOf

public int indexOf(int ch, int fromIndex)
This method determines the index of the first occurrence of the specified character in this string beginning at fromIndex.
Parameters:
ch-the character to search for.
fromIndex-the index to start the search from.
Returns: The index of the first occurrence of the specified character beginning at fromIndex, or -1 if the character doesn't occur.

indexOf

public int indexOf(String str)
This method determines the index of the first occurrence of the specified substring in this string.
Parameters: str-the substring to search for.
Returns: The index of the first occurrence of the specified substring, or -1 if the substring doesn't occur.

indexOf

public int indexOf(String str, int fromIndex)
This method determines the index of the first occurrence of the specified substring in this string, beginning at fromIndex.
Parameters:
str-the substring to search for.
fromIndex-the index to start the search from.
Returns: The index of the first occurrence of the specified substring beginning at fromIndex, or -1 if the substring doesn't occur.

intern

public String intern()
This method determines a string that is equal to this string, but is guaranteed to be from a pool of unique strings.
Returns: A string that is equal to this string, but is guaranteed to be from a pool of unique strings.

lastIndexOf

public int lastIndexOf(int ch)
This method determines the index of the last occurrence of the specified character in this string.
Parameters: ch-the character to search for.
Returns: The index of the last occurrence of the specified character, or -1 if the character doesn't occur.

lastIndexOf

public int lastIndexOf(int ch, int fromIndex)
This method determines the index of the last occurrence of the specified character in this string, beginning at fromIndex.
Parameters:
ch-the character to search for.
fromIndex-the index to start the search from.
Returns: The index of the last occurrence of the specified character beginning at fromIndex, or -1 if the character doesn't occur.

lastIndexOf

public int lastIndexOf(String str)
This method determines the index of the last occurrence of the specified substring in this string.
Parameters: str-the substring to search for.
Returns: The index of the last occurrence of the specified substring, or -1 if the substring doesn't occur.

lastIndexOf

public int lastIndexOf(String str, int fromIndex)
This method determines the index of the last occurrence of the specified substring in this string beginning at fromIndex.
Parameters:
str-the substring to search for.
fromIndex-the index to start the search from.
Returns: The index of the last occurrence of the specified substring beginning at fromIndex, or -1 if the substring doesn't occur.

length

public int length()
This method determines the length of this string, which is the number of Unicode characters in the string.
Returns: The length of this string.

regionMatches

public boolean regionMatches(boolean ignoreCase, int toffset,
String other,int ooffset, int len)
This method determines whether a substring of this string matches a substring of the specified string, with an option for ignoring case.
Parameters:
ignoreCase-a boolean value specifying whether case is ignored; a value of true means case is ignored, where a value of false means case isn't ignored.
toffset-the index to start the substring for this string.
other-the other string to compare.
ooffset-the index to start the substring for the string to compare.
len-the number of characters to compare.
Returns: true if the substring of this string matches the substring of the specified string; false otherwise.

regionMatches

public boolean regionMatches(int toffset, String other, int ooffset, int len)
This method determines whether a substring of this string matches a substring of the specified string.
Parameters:
toffset-the index to start the substring for this string.
other-the other string to compare.
ooffset-the index to start the substring for the string to compare.
len-the number of characters to compare.
Returns: true if the substring of this string matches the substring of the specified string; false otherwise.

replace

public String replace(char oldChar, char newChar)
This method replaces all occurrences of oldChar in this string with newChar.
Parameters:
oldChar-the old character to replace.
newChar-the new character to take its place.
Returns: This string, with all occurrences of oldChar replaced with newChar.

startsWith

public boolean startsWith(String prefix)
This method determines whether this string starts with the specified prefix.
Parameters: prefix-the prefix to check.
Returns: true if this string starts with the specified prefix; false otherwise.

startsWith

public boolean startsWith(String prefix, int fromIndex)
This method determines whether this string starts with the specified prefix beginning at fromIndex.
Parameters:
prefix-the prefix to check.
fromIndex-the index to start the search from.
Returns: true if this string starts with the specified prefix beginning at fromIndex; false otherwise.

substring

public String substring(int beginIndex)
This method determines the substring of this string beginning at beginIndex.
Parameters: beginIndex-the beginning index of the substring, inclusive.
Returns: The substring of this string beginning at beginIndex.
Throws: StringIndexOutOfBoundsException if beginIndex is out of range.

substring

public String substring(int beginIndex, int endIndex)
This method determines the substring of this string beginning at beginIndex and ending at endIndex.
Parameters:
beginIndex-the beginning index of the substring, inclusive.
endIndex-the end index of the substring, exclusive.
Returns: The substring of this string beginning at beginIndex and ending at endIndex.
Throws: StringIndexOutOfBoundsException if beginIndex or endIndex is out of range.

toCharArray

public char[] toCharArray()
This method converts this string to a character array by creating a new array and copying each character of the string to it.
Returns: A character array representing this string.

toLowerCase

public String toLowerCase()
This method converts all the characters in this string to lowercase.
Returns: This string, with all the characters converted to lowercase.

toString

public String toString()
This method returns this string.
Returns: This string itself.

toUpperCase

public String toUpperCase()
This method converts all the characters in this string to uppercase.
Returns: This string, with all the characters converted to uppercase.

trim

public String trim()
This method trims leading and trailing whitespace from this string.
Returns: This string, with leading and trailing whitespace removed.

valueOf

public static String valueOf(boolean b)
This method creates a string representation of the specified boolean value. If the boolean value is true, the string "true" is returned; otherwise, the string "false" is returned.
Parameters: b-the boolean value to get the string representation of.
Returns: A string representation of the specified boolean value.

valueOf

public static String valueOf(char c)
This method creates a string representation of the specified character value.
Parameters: c-the character value to get the string representation of.
Returns: A string representation of the specified character value.

valueOf

public static String valueOf(char data[])
This method creates a string representation of the specified character array.
Parameters: data-the character array to get the string representation of.
Returns: A string representation of the specified character array.

valueOf

public static String valueOf(char data[], int off, int count)
This constructor creates a string representation of length count from the specified array of characters beginning off bytes into the array.
Parameters:
data-the character array to get the string representation of.
off-the starting offset into the array of characters.
count-the number of characters from the array to use in initializing the string.
Returns: A string representation of the specified character array.

valueOf

public static String valueOf(double d)
This method creates a string representation of the specified double value.
Parameters: d-the double value to get the string representation of.
Returns: A string representation of the specified double value.

valueOf

public static String valueOf(float f)
This method creates a string representation of the specified float value.
Parameters: f-the float value to get the string representation of.
Returns: A string representation of the specified float value.

valueOf

public static String valueOf(int i)
This method creates a string representation of the specified integer value.
Parameters: i-the integer value to get the string representation of.
Returns: A string representation of the specified integer value.

valueOf

public static String valueOf(long l)
This method creates a string representation of the specified long value.
Parameters: l-the long value to get the string representation of.
Returns: A string representation of the specified long value.

valueOf

public static String valueOf(Object obj)
This method creates a string representation of the specified object. Note that the string representation is the same as that returned by the toString method of the object.
Parameters: obj-the object to get the string representation of.
Returns: A string representation of the specified object value, or the string "null" if the object is null.

StringBuffer

Extends: Object
This class implements a variable string of characters. The StringBuffer class provides a wide range of append and insert methods, along with some other support methods for getting information about the string buffer.

StringBuffer Constructor

public StringBuffer()
This constructor creates a default string buffer with no characters.

StringBuffer Constructor

public StringBuffer(int length)
This constructor creates a string buffer with the specified length.
Parameters: length-the initial length of the string buffer.

StringBuffer Constructor

public StringBuffer(String str)
This constructor creates a string buffer with the specified initial string value.
Parameters: str-the initial string value of the string buffer.

append

public StringBuffer append(boolean b)
This method appends the string representation of the specified boolean value to the end of this string buffer.
Parameters: b-the boolean value to be appended.
Returns: This string buffer, with the boolean appended.

append

public StringBuffer append(char c)
This method appends the string representation of the specified character value to the end of this string buffer.
Parameters: c-the character value to be appended.
Returns: This string buffer, with the character appended.

append

public StringBuffer append(char str[])
This method appends the string representation of the specified character array to the end of this string buffer.
Parameters: str-the character array to be appended.
Returns: This string buffer, with the character array appended.

append

public StringBuffer append(char str[], int off, int len)
This method appends the string representation of the specified character subarray to the end of this string buffer.
Parameters:
str-the character array to be appended.
off-the starting offset into the character array to append.
len-the number of characters to append.
Returns: This string buffer, with the character subarray appended.

append

public StringBuffer append(double d)
This method appends the string representation of the specified double value to the end of this string buffer.
Parameters: d-the double value to be appended.
Returns: This string buffer, with the double appended.

append

public StringBuffer append(float f)
This method appends the string representation of the specified float value to the end of this string buffer.
Parameters: f-the float value to be appended.
Returns: This string buffer, with the float appended.

append

public StringBuffer append(int i)
This method appends the string representation of the specified integer value to the end of this string buffer.
Parameters: i-the integer value to be appended.
Returns: This string buffer, with the integer appended.

append

public StringBuffer append(long l)
This method appends the string representation of the specified long value to the end of this string buffer.
Parameters: l-the long value to be appended.
Returns: This string buffer, with the long appended.

append

public StringBuffer append(Object obj)
This method appends the string representation of the specified object to the end of this string buffer.
Parameters: obj-the object to be appended.
Returns: This string buffer, with the object appended.

append

public StringBuffer append(String str)
This method appends the specified string to the end of this string buffer.
Parameters: str-the string to be appended.
Returns: This string buffer, with the string appended.

capacity

public int capacity()
This method determines the capacity of this string buffer, which is the amount of character storage currently allocated in the string buffer.
Returns: The capacity of this string buffer.

charAt

public char charAt(int index)
This method determines the character at the specified index. Note that string buffer indexes are zero based, meaning that the first character is located at index 0.
Parameters: index-the index of the desired character.
Returns: The character at the specified index.
Throws: StringIndexOutOfBoundsException if the index is out of range.

ensureCapacity

public void ensureCapacity(int minimumCapacity)
This method ensures that the capacity of this string buffer is at least equal to the specified minimum.
Parameters: minimumCapacity-the minimum desired capacity.

getChars

public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin)
This method copies each character in this string buffer beginning at srcBegin and ending at srcEnd into the character array dst beginning at dstBegin.
Parameters:
srcBegin-index of the first character in the string buffer to copy.
srcEnd-index of the last character in the string buffer to copy.
dst-the destination character array.
dstBegin-the starting offset into the character array.
Throws: StringIndexOutOfBoundsException if there is an invalid index into the buffer.

insert

public StringBuffer insert(int off, boolean b)
This method inserts the string representation of the specified boolean value at the specified offset of this string buffer.
Parameters:
off-the offset at which to insert the boolean.
b-the boolean value to be inserted.
Returns: This string buffer, with the boolean inserted.
Throws: StringIndexOutOfBoundsException if the offset is invalid.

insert

public StringBuffer insert(int off, char c)
This method inserts the string representation of the specified character value at the specified offset of this string buffer.
Parameters:
off-the offset at which to insert the character.
c-the character value to be inserted.
Returns: This string buffer, with the character inserted.
Throws: StringIndexOutOfBoundsException if the offset is invalid.

insert

public StringBuffer insert(int off, char str[])
This method inserts the string representation of the specified character array at the specified offset of this string buffer.
Parameters:
off-the offset at which to insert the character array.
str-the character array to be inserted.
Returns: This string buffer, with the character array inserted.
Throws: StringIndexOutOfBoundsException if the offset is invalid.

insert

public StringBuffer insert(int off, double d)
This method inserts the string representation of the specified double value at the specified offset of this string buffer.
Parameters:
off-the offset at which to insert the double.
d-the double value to be inserted.
Returns: This string buffer, with the double inserted.
Throws: StringIndexOutOfBoundsException if the offset is invalid.

insert

public StringBuffer insert(int off, float f)
This method inserts the string representation of the specified float value at the specified offset of this string buffer.
Parameters:
off-the offset at which to insert the float.
f-the float value to be inserted.
Returns: This string buffer, with the float inserted.
Throws: StringIndexOutOfBoundsException if the offset is invalid.

insert

public StringBuffer insert(int off, int i)
This method inserts the string representation of the specified integer value at the specified offset of this string buffer.
Parameters:
off-the offset at which to insert the integer.
i-the integer value to be inserted.
Returns: This string buffer, with the integer inserted.
Throws: StringIndexOutOfBoundsException if the offset is invalid.

insert

public StringBuffer insert(int off, long l)
This method inserts the string representation of the specified long value at the specified offset of this string buffer.
Parameters:
off-the offset at which to insert the long.
l-the long value to be inserted.
Returns: This string buffer, with the long inserted.
Throws: StringIndexOutOfBoundsException if the offset is invalid.

insert

public StringBuffer insert(int off, Object obj)
This method inserts the string representation of the specified object at the specified offset of this string buffer.
Parameters:
off-the offset at which to insert the object.
obj-the object to be inserted.
Returns: This string buffer, with the object inserted.
Throws: StringIndexOutOfBoundsException if the offset is invalid.

insert

public StringBuffer insert(int off, String str)
This method inserts the specified string at the specified offset of this string buffer.
Parameters:
off-the offset at which to insert the string.
str-the string to be inserted.
Returns: This string buffer, with the string inserted.
Throws: StringIndexOutOfBoundsException if the offset is invalid.

length

public int length()
This method determines the length of this string buffer, which is the actual number of characters stored in the buffer.
Returns: The length of this string buffer.

reverse

public StringBuffer reverse()
This method reverses the character sequence in this string buffer.
Returns: This string buffer, with the characters reversed.

setCharAt

public void setCharAt(int index, char ch)
This method changes the character at the specified index in this string to the specified character.
Parameters:
index-the index of the character to change.
ch-the new character.
Throws: StringIndexOutOfBoundsException if the index is invalid.

setLength

public void setLength(int newLength)
This method explicitly sets the length of this string buffer. If the length is reduced, characters are lost; if the length is increased, new characters are set to 0 (null).
Parameters: newLength-the new length of the string buffer.
Throws: StringIndexOutOfBoundsException if the length is invalid.

toString

public String toString()
This method determines a constant string representation of this string buffer.
Returns: The constant string representation of this string buffer.

System

Extends: Object
This class provides a platform-independent means of interacting with the Java runtime system. The System class provides support for standard input, standard output, and standard error streams, along with providing access to system properties, among other things.

Member Variables

public static PrintStream err

This is the standard error stream, which is used for printing error information. Typically this stream corresponds to display output since it is important that the user see the error information.

public static InputStream in

This is the standard input stream, which is used for reading character data. Typically this stream corresponds to keyboard input or another input source specified by the host environment or user.

public static PrintStream out

This is the standard output stream, which is used for printing character data. Typically this stream corresponds to display output or another output destination specified by the host environment or user.

arraycopy

public static void arraycopy(Object src, int src_position, Object dst,
int dst_position, int len)
This method copies len array elements from the src array beginning at src_position to the dst array beginning at dst_position. Both src and dst must be array objects. Note that arraycopy does not allocate memory for the destination array; the memory must already be allocated.
Parameters:
src-the source array to copy data from.
src_position-the start position in the source array.
dst-the destination array to copy data to.
dst_position-the start position in the destination array.
len-the number of array elements to be copied.
Throws: ArrayIndexOutOfBoundsException if the copy would cause data to be accessed outside of array bounds.
Throws: ArrayStoreException if an element in the source array could not be stored in the destination array due to a type mismatch.

currentTimeMillis

public static long currentTimeMillis()
This method determines the current UTC time relative to midnight, January 1, 1970 UTC, in milliseconds.
Returns: The current UTC time relative to midnight, January 1, 1970 UTC, in milliseconds.

exit

public static void exit(int status)
This method exits the Java runtime system (virtual machine) with the specified integer exit status. Note that since exit kills the runtime system, it never returns.
Parameters: status-the integer exit status; this should be set to nonzero if this is an abnormal exit.
Throws: SecurityException if the current thread cannot exit with the specified exit status.

gc

public static void gc()
This method invokes the Java garbage collector to clean up any objects that are no longer needed, usually resulting in more free memory.

getProperties

public static Properties getProperties()
This method determines the current system properties. Following is a list of all the system properties guaranteed to be supported:
Returns: The current system properties.
Throws: SecurityException if the current thread cannot access the system
properties.

getProperty

public static String getProperty(String key)
This method determines the system property with the specified key name.
Parameters: key-the key name of the system property.
Returns: The system property with the specified key name.
Throws: SecurityException if the current thread cannot access the system property.

getProperty

public static String getProperty(String key, String def)
This method determines the system property with the specified key name; it returns the specified default property value if the key isn't found.
Parameters:
key-the key name of the system property.
def-the default property value to use if the key isn't found.
Returns: The system property with the specified key name, or the specified default property value if the key isn't found.
Throws: SecurityException if the current thread cannot access the system property.

getSecurityManager

public static SecurityManager getSecurityManager()
This method gets the security manager for the Java program, or null if none exists.
Returns: The security manager for the Java program, or null if none exists.

load

public static void load(String pathname)
This method loads the dynamic library with the specified complete path name. This method simply calls the load method in the Runtime class.
Parameters: pathname-the path name of the library to load.
Throws: UnsatisfiedLinkError if the library doesn't exist.
Throws: SecurityException if the current thread can't load the library.

loadLibrary

public static void loadLibrary(String libname)
This method loads the dynamic library with the specified library name. Note that the mapping from library name to a specific filename is performed in a platform-specific manner.
Parameters: libname-the name of the library to load.
Throws: UnsatisfiedLinkError if the library doesn't exist.
Throws: SecurityException if the current thread can't load the library.

runFinalization

public static void runFinalization()
This method explicitly causes the finalize methods of any discarded objects to be called. Typically, the finalize methods of discarded objects are automatically called asynchronously when the garbage collector cleans up the objects. You can use runFinalization to have the finalize methods called synchronously.

setProperties

public static void setProperties(Properties props)
This method sets the system properties to the specified properties.
Parameters: props-the new properties to be set.

setSecurityManager

public static void setSecurityManager(SecurityManager s)
This method sets the security manager to the specified security manager. Note that the security manager can be set only once for a Java program.
Parameters: s-the new security manager to be set.
Throws: SecurityException if the security manager has already been set.

Thread

Extends: Object
Implements: Runnable
This class provides the overhead necessary to manage a single thread of execution within a process. The Thread class is the basis for multithreaded programming in Java.

Member Constants

public final static int MAX_PRIORITY

This is a constant representing the maximum priority a thread can have, which is set to 10.

public final static int MIN_PRIORITY

This is a constant representing the minimum priority a thread can have, which is set to 1.

public final static int NORM_PRIORITY

This is a constant representing the normal (default) priority for a thread, which is set to 5.

Thread Constructor

public Thread()
This constructor creates a default thread. Note that threads created with this constructor must have overridden their run method to actually do anything.

Thread Constructor

public Thread(Runnable target)
This constructor creates a thread that uses the run method of the specified runnable.
Parameters: target-the object whose run method is used by the thread.

Thread Constructor

public Thread(ThreadGroup group, Runnable target)
This constructor creates a thread belonging to the specified thread group that uses the run method of the specified runnable.
Parameters:
group-the thread group the thread is to be a member of.
target-the object whose run method is used by the thread.

Thread Constructor

public Thread(String name)
This constructor creates a thread with the specified name.
Parameters: name-the name of the new thread.

Thread Constructor

public Thread(ThreadGroup group, String name)
This constructor creates a thread belonging to the specified thread group with the specified name.
Parameters:
group-the thread group the thread is to be a member of.
name-the name of the new thread.

Thread Constructor

public Thread(Runnable target, String name)
This constructor creates a thread with the specified name that uses the run method of the specified runnable.
Parameters:
target-the object whose run method is used by the thread.
name-the name of the new thread.

Thread Constructor

public Thread(ThreadGroup group, Runnable target, String name)
This constructor creates a thread belonging to the specified thread group with the specified name that uses the run method of the specified runnable.
Parameters:
group-the thread group the thread is to be a member of.
target-the object whose run method is used by the thread.
name-the name of the new thread.

activeCount

public static int activeCount()
This method determines the number of active threads in this thread's thread group.
Returns: The number of active threads in this thread's thread group.

checkAccess

public void checkAccess()
This method checks to see if the currently running thread is allowed access to this thread.
Throws: SecurityException if the calling thread doesn't have access to this thread.

countStackFrames

public int countStackFrames()
This method determines the number of stack frames in this thread. Note that the thread must be suspended to use this method.
Returns: The number of stack frames in this thread.
Throws: IllegalThreadStateException if the thread is not suspended.

currentThread

public static Thread currentThread()
This method determines the currently running thread.
Returns: The currently running thread.

destroy

public void destroy()
This method destroys this thread without performing any cleanup, meaning that any monitors locked by the thread remain locked. Note that this method should only be used as a last resort for destroying a thread.

dumpStack

public static void dumpStack()
This method prints a stack trace for this thread. Note that this method is useful only for debugging.

enumerate

public static int enumerate(Thread list[])
This method fills the specified array with references to every active thread in this thread's thread group.
Parameters: list-an array to hold the enumerated threads.
Returns: The number of threads added to the array.

getName

public final String getName()
This method determines the name of this thread.
Returns: The name of this thread.

getPriority

public final int getPriority()
This method determines the priority of this thread.
Returns: The priority of this thread.

getThreadGroup

public final ThreadGroup getThreadGroup()
This method determines the thread group for this thread.
Returns: The thread group for this thread.

interrupt

public void interrupt()
This method interrupts this thread.

interrupted

public static boolean interrupted()
This method determines if this thread has been interrupted.
Returns: true if the thread has been interrupted; false otherwise.

isAlive

public final boolean isAlive()
This method determines if this thread is active. An active thread is a thread that has been started and has not yet stopped.
Returns: true if the thread is active; false otherwise.

isDaemon

public final boolean isDaemon()
This method determines if this thread is a daemon thread. A daemon thread is a background thread that is owned by the runtime system rather than a specific process.
Returns: true if the thread is a daemon thread; false otherwise.

isInterrupted

public boolean isInterrupted()
This method determines if this thread has been interrupted.
Returns: true if the thread has been interrupted; false otherwise.

join

public final void join() throws InterruptedException
This method causes the current thread to wait indefinitely until it dies.
Throws: InterruptedException if another thread has interrupted this thread.

join

public final void join(long timeout) throws InterruptedException
This method causes the current thread to wait until it dies, or until the specified timeout period has elapsed.
Parameters: timeout-the maximum timeout period to wait, in milliseconds.
Throws: InterruptedException if another thread has interrupted this thread.

join

public final void join(long timeout, int nanos) throws InterruptedException
This method causes the current thread to wait until it dies, or until the specified timeout period has elapsed. The timeout period in this case is the addition of the timeout and nanos parameters, which provide finer control over the timeout period.
Parameters:
timeout-the maximum timeout period to wait, in milliseconds.
nanos-the additional time for the timeout period, in nanoseconds.
Throws: InterruptedException if another thread has interrupted this thread.

resume

public final void resume()
This method resumes this thread's execution if it has been suspended.
Throws: SecurityException if the current thread doesn't have access to this thread.

run

public void run()
This method is the body of the thread, which performs the actual work of the thread. The run method is called when the thread is started. The run method is either overridden in a derived Thread class or implemented in a class implementing the Runnable interface.

setDaemon

public final void setDaemon(boolean daemon)
This method sets this thread as either a daemon thread or a user thread based on the specified boolean value. Note that the thread must be inactive to use this method.
Parameters: daemon-a boolean value that determines whether the thread is a daemon thread.
Throws: IllegalThreadStateException if the thread is active.

setName

public final void setName(String name)
This method sets the name of this thread.
Parameters: name-the new name of the thread.
Throws: SecurityException if the current thread doesn't have access to this thread.

setPriority

public final void setPriority(int newPriority)
This method sets the priority of this thread.
Parameters: newPriority-the new priority of the thread.
Throws: IllegalArgumentException if the priority is not within the range MIN_PRIORITY to MAX_PRIORITY.
Throws: SecurityException if the current thread doesn't have access to this thread.

sleep

public static void sleep(long millis) throws InterruptedException
This method causes the current thread to sleep for the specified length of time, in milliseconds.
Parameters: millis-the length of time to sleep, in milliseconds.
Throws: InterruptedException if another thread has interrupted this thread.

sleep

public static void sleep(long millis, int nanos) throws InterruptedException
This method causes the current thread to sleep for the specified length of time. The length of time in this case is the addition of the millis and nanos parameters, which provide finer control over the sleep time.
Parameters:
millis-the length of time to sleep, in milliseconds.
nanos-the additional time for the sleep time, in nanoseconds.
Throws: InterruptedException if another thread has interrupted this thread.

start

public void start()
This method starts this thread, causing the run method to be executed.
Throws: IllegalThreadStateException if the thread was already running.

stop

public final void stop()
This method abnormally stops this thread, causing it to throw a ThreadDeath object. You can catch the ThreadDeath object to perform cleanup, but there is rarely a need to do so.
Throws: SecurityException if the current thread doesn't have access to this thread.

stop

public final synchronized void stop(Throwable o)
This method abnormally stops this thread, causing it to throw the specified object. Note that this version of stop should be used only in very rare situations.
Parameters: o-the object to be thrown.
Throws: SecurityException if the current thread doesn't have access to this thread.

suspend

public final void suspend()
This method suspends the execution of this thread.
Throws: SecurityException if the current thread doesn't have access to this thread.

toString

public String toString()
This method determines a string representation of this thread, which includes the thread's name, priority, and thread group.
Returns: A string representation of this thread.

yield

public static void yield()
This method causes the currently executing thread to yield so that other threads can execute.

ThreadGroup

Extends: Object
This class implements a thread group, which is a set of threads that can be manipulated as one. Thread groups can also contain other thread groups, resulting in a thread hierarchy.

ThreadGroup Constructor

public ThreadGroup(String name)
This constructor creates a thread group with the specified name. The newly created thread group belongs to the thread group of the current thread.
Parameters: name-the name of the new thread group.

ThreadGroup Constructor

public ThreadGroup(ThreadGroup parent, String name)
This constructor creates a thread group with the specified name and belonging to the specified parent thread group.
Parameters:
parent-the parent thread group.
name-the name of the new thread group.
Throws: NullPointerException if the specified thread group is null.
Throws: SecurityException if the current thread cannot create a thread in the specified thread group.

activeCount

public int activeCount()
This method determines the number of active threads in this thread group or in any other thread group that has this thread group as an ancestor.
Returns: The number of active threads in this thread group or in any other thread group that has this thread group as an ancestor.

activeGroupCount

public int activeGroupCount()
This method determines the number of active thread groups that have this thread group as an ancestor.
Returns: The number of active thread groups that have this thread group as an ancestor.

checkAccess

public final void checkAccess()
This method checks to see if the currently running thread is allowed access to this thread group.
Throws: SecurityException if the calling thread doesn't have access to this thread group.

destroy

public final void destroy()
This method destroys this thread group and all of its subgroups.
Throws: IllegalThreadStateException if the thread group is not empty or if it was already destroyed.
Throws: SecurityException if the calling thread doesn't have access to this thread group.

enumerate

public int enumerate(Thread list[])
This method fills the specified array with references to every active thread in this thread group.
Parameters: list-an array to hold the enumerated threads.
Returns: The number of threads added to the array.

enumerate

public int enumerate(Thread list[], boolean recurse)
This method fills the specified array with references to every active thread in this thread group. If the recurse parameter is set to true, all the active threads belonging to subgroups of this thread are also added to the array.
Parameters:
list-an array to hold the enumerated threads.
recurse-a boolean value specifying whether to recursively enumerate active threads in subgroups.
Returns: The number of threads added to the array.

enumerate

public int enumerate(ThreadGroup list[])
This method fills the specified array with references to every active subgroup in this thread group.
Parameters: list-an array to hold the enumerated thread groups.
Returns: The number of thread groups added to the array.

enumerate

public int enumerate(ThreadGroup list[], boolean recurse)
This method fills the specified array with references to every active subgroup in this thread group. If the recurse parameter is set to true, all the active thread groups belonging to subgroups of this thread are also added to the array.
Parameters:
list-an array to hold the enumerated thread groups.
recurse-a boolean value specifying whether to recursively enumerate active thread groups in subgroups.
Returns: The number of thread groups added to the array.

getMaxPriority

public final int getMaxPriority()
This method determines the maximum priority of this thread group. Note that threads in this thread group cannot have a higher priority than the maximum priority.
Returns: The maximum priority of this thread group.

getName

public final String getName()
This method determines the name of this thread group.
Returns: The name of this thread group.

getParent

public final ThreadGroup getParent()
This method determines the parent of this thread group.
Returns: The parent of this thread group.

isDaemon

public final boolean isDaemon()
This method determines if this thread group is a daemon thread group. A daemon thread group is automatically destroyed when all its threads finish executing.
Returns: true if the thread group is a daemon thread group; false otherwise.

list

public void list()
This method prints information about this thread group to standard output, including the active threads in the group. Note that this method is useful only for debugging.

parentOf

public final boolean parentOf(ThreadGroup g)
This method checks to see if this thread group is a parent or ancestor of the specified thread group.
Parameters: g-the thread group to be checked.
Returns: true if this thread group is the parent or ancestor of the specified thread group; false otherwise.

resume

public final void resume()
This method resumes execution of all the threads in this thread group that have been suspended.
Throws: SecurityException if the current thread doesn't have access to this thread group or any of its threads.

setDaemon

public final void setDaemon(boolean daemon)
This method sets this thread group as either a daemon thread group or a user thread group based on the specified boolean value. A daemon thread group is automatically destroyed when all its threads finish executing.
Parameters: daemon-a boolean value that determines whether the thread group is a daemon thread group.
Throws: SecurityException if the current thread doesn't have access to this thread group.

setMaxPriority

public final void setMaxPriority(int pri)
This method sets the maximum priority of this thread group.
Parameters: pri-the new maximum priority of the thread group.
Throws: SecurityException if the current thread doesn't have access to this thread group.

stop

public final synchronized void stop()
This method stops all the threads in this thread group and in all of its subgroups.
Throws: SecurityException if the current thread doesn't have access to this thread group, any of its threads, or threads in subgroups.

suspend

public final synchronized void suspend()
This method suspends all the threads in this thread group and in all of its subgroups.
Throws: SecurityException if the current thread doesn't have access to this thread group, any of its threads, or threads in subgroups.

toString

public String toString()
This method determines a string representation of this thread group.
Returns: A string representation of this thread group.

uncaughtException

public void uncaughtException(Thread t, Throwable e)
This method is called when a thread in this thread group exits because of an uncaught exception. You can override this method to provide specific handling of uncaught exceptions.
Parameters:
t-the thread that is exiting.
e-the uncaught exception.

Throwable

Extends: Object
This class provides the core functionality for signaling when exceptional conditions occur. All errors and exceptions in the Java system are derived from Throwable. The Throwable class contains a snapshot of the execution stack for helping to track down why exceptional conditions occur.

Throwable Constructor

public Throwable()
This constructor creates a default throwable with no detail message; the stack trace is automatically filled in.

Throwable Constructor

public constructorhrowable constructor ( constructortring constructormessage)
This constructor creates a throwable with the specified detail message; the stack trace is automatically filled in.
Parameters: message-the detail message.

fillInStackTrace

public Throwable fillInStackTrace()
This method fills in the execution stack trace. Note that this method is only useful when rethrowing this throwable.
Returns: This throwable.

getMessage

public String getMessage()
This method determines the detail message of this throwable.
Returns: The detail message of this throwable.

printStackTrace

public void printStackTrace()
This method prints this throwable and its stack trace to the standard error stream.

printStackTrace

public void printStackTrace(PrintStream s)
This method prints this throwable and its stack trace to the specified print stream.
Parameters: s-the print stream to print the stack to.

toString

public String toString()
This method determines a string representation of this throwable.
Returns: A string representation of this throwable.

RuntimeException

This exception class signals that an invalid cast has occurred.

ClassNotFoundException

Extends: Exception
This exception class signals that a class could not be found.

CloneNotSupportedException

Extends: Exception
This exception class signals that an attempt has been made to clone an object that doesn't support the Cloneable interface.

Exception

Extends: Throwable
This throwable class indicates exceptional conditions that a Java program might want to know about.

IllegalAccessException

Extends: Exception
This exception class signals that the current thread doesn't have access to a class.

IllegalArgumentException

Extends: RuntimeException
This exception class signals that a method has been passed an illegal argument.

IllegalMonitorStateException

Extends: RuntimeException
This exception class signals that a thread has attempted to access an object's monitor without owning the monitor.

IllegalThreadStateException

Extends: IllegalArgumentException
This exception class signals that a thread is not in the proper state for the requested operation.

IndexOutOfBoundsException

Extends: RuntimeException
This exception class signals that an index of some sort is out of bounds.

InstantiationException

Extends: Exception
This exception class signals that an attempt has been made to instantiate an abstract class or an interface.

InterruptedException

Extends: Exception
This exception class signals that a thread has been interrupted that is already waiting or sleeping.

NegativeArraySizeException

Extends: RuntimeException
This exception class signals that an attempt has been made to create an array with a negative size.

NullPointerException

Extends: RuntimeException
This exception class signals an attempt to access a null pointer as an object.

NumberFormatException

Extends: IllegalArgumentException
This exception class signals an attempt to convert a string to an invalid number format.

RuntimeException

Extends: Exception
This exception class signals an exceptional condition that can reasonably occur in the Java runtime system.

SecurityException

Extends: RuntimeException
This exception class signals that a security violation has occurred.

StringIndexOutOfBoundsException

Extends: IndexOutOfBoundsException
This exception class signals that an invalid string index has been used.

AbstractMethodError

Extends: IncompatibleClassChangeError
This error class signals an attempt to call an abstract method.

ClassFormatError

Extends: LinkageError
This error class signals an attempt to read a file in an invalid format.

Error

Extends: Throwable
This throwable class indicates a serious problem beyond the scope of what a Java program can fix.

IllegalAccessError

Extends: IncompatibleClassChangeError
This error class signals an attempt to access a member variable or call a method without proper access.

IncompatibleClassChangeError

Extends: LinkageError
This error class signals that an incompatible change has been made to some class definition.

InstantiationError

Extends: IncompatibleClassChangeError
This error class signals an attempt to instantiate an abstract class or an interface.

InternalError

Extends: VirtualMachineError
This error class signals that some unexpected internal error has occurred.

LinkageError

Extends: Error
This error class signals that a class has some dependency on another class, but that the latter class has incompatibly changed after the compilation of the former class.

NoClassDefFoundError

Extends: LinkageError
This error class signals that a class definition could not be found.

NoSuchFieldError

Extends: IncompatibleClassChangeError
This error class signals an attempt to access a member variable that doesn't exist.

NoSuchMethodError

Extends: IncompatibleClassChangeError
This error class signals an attempt to call a method that doesn't exist.

OutOfMemoryError

Extends: VirtualMachineError
This error class signals that the Java runtime system is out of memory.

StackOverflowError

Extends: VirtualMachineError
This error class signals that a stack overflow has occurred.

ThreadDeath

Extends: Error
This error class signals that a thread is being abnormally stopped via the stop method.

UnknownError

Extends: VirtualMachineError
This error class signals that an unknown but serious error has occurred.

UnsatisfiedLinkError

Extends: LinkageError
This error class signals that a native implementation of a method declared as native cannot be found.

VerifyError

Extends: LinkageError
This error class signals that a class has failed the runtime verification test.

VirtualMachineError

Extends: Error
This error class signals that the Java virtual machine is broken or has run out of resources necessary for it to continue operating.

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