java.lang.System Class Reference

List of all members.

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Detailed Description

Class System provides a standard place for programs to find system related information.

All System API is static.

Static Public Member Functions
static void	setIn (InputStream newIn)
	Sets the value of the static slot "in" in the receiver to the passed in argument.
static void	setOut (java.io.PrintStream newOut)
	Sets the value of the static slot "out" in the receiver to the passed in argument.
static void	setErr (java.io.PrintStream newErr)
	Sets the value of the static slot "err" in the receiver to the passed in argument.
static void	arraycopy (Object array1, int start1, Object array2, int start2, int length)
	Copies the contents of array1 starting at offset start1 into array2 starting at offset start2 for length elements.
static native long	currentTimeMillis ()
	Answers the current time expressed as milliseconds since the time 00:00:00 UTC on January 1, 1970.
static native long	nanoTime ()
static void	exit (int code)
	Causes the virtual machine to stop running, and the program to exit.
static void	gc ()
	Indicate to the virtual machine that it would be a good time to collect available memory.
static String	getenv (String var)
	Returns an environment variable.
static Map< String, String >	getenv ()
static Channel	inheritedChannel () throws IOException
static Properties	getProperties ()
	Answers the system properties.
static String	getProperty (String prop)
	Answers the value of a particular system property.
static String	getProperty (String prop, String defaultValue)
	Answers the value of a particular system property.
static String	setProperty (String prop, String value)
	Sets the value of a particular system property.
static String	clearProperty (String key)
static SecurityManager	getSecurityManager ()
	Answers the active security manager.
static native int	identityHashCode (Object anObject)
	Answers an integer hash code for the parameter.
static void	load (String pathName)
	Loads the specified file as a dynamic library.
static void	loadLibrary (String libName)
	Loads and links the library specified by the argument.
static void	runFinalization ()
	Provides a hint to the virtual machine that it would be useful to attempt to perform any outstanding object finalizations.
static void	runFinalizersOnExit (boolean flag)
	Ensure that, when the virtual machine is about to exit, all objects are finalized.
static void	setProperties (Properties p)
	Answers the system properties.
static void	setSecurityManager (final SecurityManager s)
	Sets the active security manager.
static native String	mapLibraryName (String userLibName)
	Answers the platform specific file name format for the shared library named by the argument.
Static Public Attributes
static final InputStream	in
	Default input stream.
static final PrintStream	out
	Default output stream.
static final PrintStream	err
	Default error output stream.
Static Package Functions
	[static initializer]
static Properties	internalGetProperties ()
	Answers the system properties without any security checks.
Private Member Functions
	System ()
	Prevents this class from being instantiated.
Static Private Member Functions
static void	arraycopy (Object[] A1, int offset1, Object[] A2, int offset2, int length)
	Private version of the arraycopy method (used by the jit for reference arraycopies).
static void	arraycopy (int[] A1, int offset1, int[] A2, int offset2, int length)
	Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.
static void	arraycopy (byte[] A1, int offset1, byte[] A2, int offset2, int length)
	Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.
static void	arraycopy (short[] A1, int offset1, short[] A2, int offset2, int length)
	Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.
static void	arraycopy (long[] A1, int offset1, long[] A2, int offset2, int length)
	Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.
static void	arraycopy (char[] A1, int offset1, char[] A2, int offset2, int length)
	Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.
static void	arraycopy (boolean[] A1, int offset1, boolean[] A2, int offset2, int length)
	Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.
static void	arraycopy (double[] A1, int offset1, double[] A2, int offset2, int length)
	Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.
static void	arraycopy (float[] A1, int offset1, float[] A2, int offset2, int length)
	Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.
static void	ensureProperties ()
	If systemProperties is unset, then create a new one based on the values provided by the virtual machine.
static native String[]	getPropertyList ()
	Answers an array of Strings containing key.
static native String	getEncoding (int type)
	Return the requested encoding.
static native void	setFieldImpl (String fieldName, Object stream)
	Sets the value of the named static field in the receiver to the passed in argument.
Static Private Attributes
static final Runtime	RUNTIME = Runtime.getRuntime()
static Properties	systemProperties
static SecurityManager	security
static boolean	security_initialized
static final int	InitLocale = 0
static final int	PlatformEncoding = 1
static final int	FileEncoding = 2
static final int	OSEncoding = 3

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Constructor & Destructor Documentation

java.lang.System.System

(

)

[private]

Prevents this class from being instantiated.

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Member Function Documentation

static void java.lang.System.setIn

(

InputStream

newIn

)

[static]

Sets the value of the static slot "in" in the receiver to the passed in argument.

Parameters:

newIn

the new value for in.

static void java.lang.System.setOut

(

java.io.PrintStream

newOut

)

[static]

Sets the value of the static slot "out" in the receiver to the passed in argument.

Parameters:

newOut

the new value for out.

static void java.lang.System.setErr

(

java.io.PrintStream

newErr

)

[static]

Sets the value of the static slot "err" in the receiver to the passed in argument.

Parameters:

newErr

the new value for err.

static void java.lang.System.arraycopy	(	Object	array1,
		int	start1,
		Object	array2,
		int	start2,
		int	length
	)			[static]

Copies the contents of array1 starting at offset start1 into array2 starting at offset start2 for length elements.

Parameters:

	array1	the array to copy out of
	start1	the starting index in array1
	array2	the array to copy into
	start2	the starting index in array2
	length	the number of elements in the array to copy

static void java.lang.System.arraycopy	(	Object[]	A1,
		int	offset1,
		Object[]	A2,
		int	offset2,
		int	length
	)			[static, private]

Private version of the arraycopy method (used by the jit for reference arraycopies).

static void java.lang.System.arraycopy	(	int[]	A1,
		int	offset1,
		int[]	A2,
		int	offset2,
		int	length
	)			[static, private]

Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.

Parameters:

	A1	the array to copy out of
	offset1	the starting index in array1
	A2	the array to copy into
	offset2	the starting index in array2
	length	the number of elements in the array to copy

static void java.lang.System.arraycopy	(	byte[]	A1,
		int	offset1,
		byte[]	A2,
		int	offset2,
		int	length
	)			[static, private]

Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.

Parameters:

	A1	the array to copy out of
	offset1	the starting index in array1
	A2	the array to copy into
	offset2	the starting index in array2
	length	the number of elements in the array to copy

static void java.lang.System.arraycopy	(	short[]	A1,
		int	offset1,
		short[]	A2,
		int	offset2,
		int	length
	)			[static, private]

Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.

Parameters:

	A1	the array to copy out of
	offset1	the starting index in array1
	A2	the array to copy into
	offset2	the starting index in array2
	length	the number of elements in the array to copy

static void java.lang.System.arraycopy	(	long[]	A1,
		int	offset1,
		long[]	A2,
		int	offset2,
		int	length
	)			[static, private]

Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.

Parameters:

	A1	the array to copy out of
	offset1	the starting index in array1
	A2	the array to copy into
	offset2	the starting index in array2
	length	the number of elements in the array to copy

static void java.lang.System.arraycopy	(	char[]	A1,
		int	offset1,
		char[]	A2,
		int	offset2,
		int	length
	)			[static, private]

Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.

Parameters:

	A1	the array to copy out of
	offset1	the starting index in array1
	A2	the array to copy into
	offset2	the starting index in array2
	length	the number of elements in the array to copy

static void java.lang.System.arraycopy	(	boolean[]	A1,
		int	offset1,
		boolean[]	A2,
		int	offset2,
		int	length
	)			[static, private]

Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.

Parameters:

	A1	the array to copy out of
	offset1	the starting index in array1
	A2	the array to copy into
	offset2	the starting index in array2
	length	the number of elements in the array to copy

static void java.lang.System.arraycopy	(	double[]	A1,
		int	offset1,
		double[]	A2,
		int	offset2,
		int	length
	)			[static, private]

Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.

Parameters:

	A1	the array to copy out of
	offset1	the starting index in array1
	A2	the array to copy into
	offset2	the starting index in array2
	length	the number of elements in the array to copy

static void java.lang.System.arraycopy	(	float[]	A1,
		int	offset1,
		float[]	A2,
		int	offset2,
		int	length
	)			[static, private]

Copies the contents of A1 starting at offset offset1 into A2 starting at offset offset2 for length elements.

Parameters:

	A1	the array to copy out of
	offset1	the starting index in array1
	A2	the array to copy into
	offset2	the starting index in array2
	length	the number of elements in the array to copy

static native long java.lang.System.currentTimeMillis

(

)

[static]

Answers the current time expressed as milliseconds since the time 00:00:00 UTC on January 1, 1970.

Returns:

the time in milliseconds.

static native long java.lang.System.nanoTime

(

)

[static]

Returns the most precise time measurement in nanoseconds that's available.

Returns:

The current time in nanoseconds.

static void java.lang.System.ensureProperties

(

)

[static, private]

If systemProperties is unset, then create a new one based on the values provided by the virtual machine.

static void java.lang.System.exit

(

int

code

)

[static]

Causes the virtual machine to stop running, and the program to exit.

If runFinalizersOnExit(true) has been invoked, then all finalizers will be run first.

Parameters:

code

the return code.

Exceptions:

SecurityException

if the running thread is not allowed to cause the vm to exit.

See also:

SecurityManager.checkExit

static void java.lang.System.gc

(

)

[static]

Indicate to the virtual machine that it would be a good time to collect available memory.

Note that, this is a hint only.

static String java.lang.System.getenv

(

String

var

)

[static]

Returns an environment variable.

Parameters:

var

the name of the environment variable

Returns:

the value of the specified environment variable

static Map<String, String> java.lang.System.getenv

(

)

[static]

Returns all environment variables.

Returns:

A Map of all environment variables.

static Channel java.lang.System.inheritedChannel

(

)

throws IOException [static]

Returns the inherited channel from the system-wide provider.

Returns:

A Channel or null.

Exceptions:

IOException

See also:

SelectorProvider

SelectorProvider.inheritedChannel()

static Properties java.lang.System.getProperties

(

)

[static]

Answers the system properties.

Note that this is not a copy, so that changes made to the returned Properties object will be reflected in subsequent calls to getProperty and getProperties.

Security managers should restrict access to this API if possible.

Returns:

the system properties

static Properties java.lang.System.internalGetProperties

(

)

[static, package]

Answers the system properties without any security checks.

This is used for access from within java.lang.

Returns:

the system properties

static String java.lang.System.getProperty

(

String

prop

)

[static]

Answers the value of a particular system property.

Answers null if no such property exists,

The properties currently provided by the virtual machine are:

        java.vendor.url
        java.class.path
        user.home
        java.class.version
        os.version
        java.vendor
        user.dir
        user.timezone
        path.separator
        os.name
        os.arch
        line.separator
        file.separator
        user.name
        java.version
        java.home
 

Parameters:

prop

the system property to look up

Returns:

the value of the specified system property, or null if the property doesn't exist

static String java.lang.System.getProperty	(	String	prop,
		String	defaultValue
	)			[static]

Answers the value of a particular system property.

If no such property is found, answers the defaultValue.

Parameters:

	prop	the system property to look up
	defaultValue	return value if system property is not found

Returns:

the value of the specified system property, or defaultValue if the property doesn't exist

static String java.lang.System.setProperty	(	String	prop,
		String	value
	)			[static]

Sets the value of a particular system property.

Parameters:

	prop	the system property to change
	value	the value to associate with prop

Returns:

the old value of the property, or null

static String java.lang.System.clearProperty

(

String

key

)

[static]

Removes the system property for the specified key.

Please see the Java SE API documentation for further information on this method.

Parameters:

key

the system property to be removed.

Returns:

previous value or null if no value existed

Exceptions:

	NullPointerException	if the key argument is null.
	IllegalArgumentException	if the key argument is empty.
	SecurityException	if a security manager exists and write access to the specified property is not allowed.

Since:

1.5

static native String [] java.lang.System.getPropertyList

(

)

[static, private]

Answers an array of Strings containing key.

.value pairs (in consecutive array elements) which represent the starting values for the system properties as provided by the virtual machine.

Returns:

the default values for the system properties.

static native String java.lang.System.getEncoding

(

int

type

)

[static, private]

Return the requested encoding.

0 - initialize locale 1 - detected platform encoding 2 - command line defined file.encoding 3 - command line defined os.encoding

static SecurityManager java.lang.System.getSecurityManager

(

)

[static]

Answers the active security manager.

Returns:

the system security manager object.

static native int java.lang.System.identityHashCode

(

Object

anObject

)

[static]

Answers an integer hash code for the parameter.

The hash code returned is the same one that would be returned by java.lang.Object.hashCode(), whether or not the object's class has overridden hashCode(). The hash code for null is 0.

Parameters:

anObject

the object

Returns:

the hash code for the object

See also:

java.lang.Object.hashCode

static void java.lang.System.load

(

String

pathName

)

[static]

Loads the specified file as a dynamic library.

Parameters:

pathName

the path of the file to be loaded

static void java.lang.System.loadLibrary

(

String

libName

)

[static]

Loads and links the library specified by the argument.

Parameters:

libName

the name of the library to load

Exceptions:

	UnsatisfiedLinkError	if the library could not be loaded
	SecurityException	if the library was not allowed to be loaded

static void java.lang.System.runFinalization

(

)

[static]

Provides a hint to the virtual machine that it would be useful to attempt to perform any outstanding object finalizations.

static void java.lang.System.runFinalizersOnExit

(

boolean

flag

)

[static]

Ensure that, when the virtual machine is about to exit, all objects are finalized.

Note that all finalization which occurs when the system is exiting is performed after all running threads have been terminated.

Parameters:

flag

true means finalize all on exit.

Deprecated:

This method is unsafe.

static void java.lang.System.setProperties

(

Properties

p

)

[static]

Answers the system properties.

Note that the object which is passed in not copied, so that subsequent changes made to the object will be reflected in calls to getProperty and getProperties.

Security managers should restrict access to this API if possible.

Parameters:

p

the property to set

static void java.lang.System.setSecurityManager

(

final SecurityManager

s

)

[static]

Sets the active security manager.

Note that once the security manager has been set, it can not be changed. Attempts to do so will cause a security exception.

Parameters:

s

the new security manager

Exceptions:

SecurityException

if the security manager has already been set.

static native String java.lang.System.mapLibraryName

(

String

userLibName

)

[static]

Answers the platform specific file name format for the shared library named by the argument.

Parameters:

userLibName

the name of the library to look up.

Returns:

the platform specific filename for the library

static native void java.lang.System.setFieldImpl	(	String	fieldName,
		Object	stream
	)			[static, private]

Sets the value of the named static field in the receiver to the passed in argument.

Parameters:

	fieldName	the name of the field to set, one of in, out, or err
	stream	the new value of the field

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Member Data Documentation

final InputStream java.lang.System.in [static]

Default input stream.

final PrintStream java.lang.System.out [static]

Default output stream.

final PrintStream java.lang.System.err [static]

Default error output stream.

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The documentation for this class was generated from the following file:

• java/lang/System.java

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