java.lang
Class Runtime

java.lang.Object sample code for java.lang.Object definition code for java.lang.Object 
  extended by java.lang.Runtime

public class Runtime
extends Object sample code for java.lang.Object definition code for java.lang.Object

Every Java application has a single instance of class Runtime that allows the application to interface with the environment in which the application is running. The current runtime can be obtained from the getRuntime method.

An application cannot create its own instance of this class.

Since:
JDK1.0
See Also:
getRuntime() sample code for java.lang.Runtime.getRuntime() definition code for java.lang.Runtime.getRuntime()

Method Summary
 void addShutdownHook sample code for java.lang.Runtime.addShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.addShutdownHook(java.lang.Thread) (Thread sample code for java.lang.Thread definition code for java.lang.Thread  hook)
          Registers a new virtual-machine shutdown hook.
 int availableProcessors sample code for java.lang.Runtime.availableProcessors() definition code for java.lang.Runtime.availableProcessors() ()
          Returns the number of processors available to the Java virtual machine.
 Process sample code for java.lang.Process definition code for java.lang.Process exec sample code for java.lang.Runtime.exec(java.lang.String) definition code for java.lang.Runtime.exec(java.lang.String) (String sample code for java.lang.String definition code for java.lang.String  command)
          Executes the specified string command in a separate process.
 Process sample code for java.lang.Process definition code for java.lang.Process exec sample code for java.lang.Runtime.exec(java.lang.String[]) definition code for java.lang.Runtime.exec(java.lang.String[]) (String sample code for java.lang.String definition code for java.lang.String [] cmdarray)
          Executes the specified command and arguments in a separate process.
 Process sample code for java.lang.Process definition code for java.lang.Process exec sample code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[]) definition code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[]) (String sample code for java.lang.String definition code for java.lang.String [] cmdarray, String sample code for java.lang.String definition code for java.lang.String [] envp)
          Executes the specified command and arguments in a separate process with the specified environment.
 Process sample code for java.lang.Process definition code for java.lang.Process exec sample code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) (String sample code for java.lang.String definition code for java.lang.String [] cmdarray, String sample code for java.lang.String definition code for java.lang.String [] envp, File sample code for java.io.File definition code for java.io.File  dir)
          Executes the specified command and arguments in a separate process with the specified environment and working directory.
 Process sample code for java.lang.Process definition code for java.lang.Process exec sample code for java.lang.Runtime.exec(java.lang.String, java.lang.String[]) definition code for java.lang.Runtime.exec(java.lang.String, java.lang.String[]) (String sample code for java.lang.String definition code for java.lang.String  command, String sample code for java.lang.String definition code for java.lang.String [] envp)
          Executes the specified string command in a separate process with the specified environment.
 Process sample code for java.lang.Process definition code for java.lang.Process exec sample code for java.lang.Runtime.exec(java.lang.String, java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String, java.lang.String[], java.io.File) (String sample code for java.lang.String definition code for java.lang.String  command, String sample code for java.lang.String definition code for java.lang.String [] envp, File sample code for java.io.File definition code for java.io.File  dir)
          Executes the specified string command in a separate process with the specified environment and working directory.
 void exit sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int) (int status)
          Terminates the currently running Java virtual machine by initiating its shutdown sequence.
 long freeMemory sample code for java.lang.Runtime.freeMemory() definition code for java.lang.Runtime.freeMemory() ()
          Returns the amount of free memory in the Java Virtual Machine.
 void gc sample code for java.lang.Runtime.gc() definition code for java.lang.Runtime.gc() ()
          Runs the garbage collector.
 InputStream sample code for java.io.InputStream definition code for java.io.InputStream getLocalizedInputStream sample code for java.lang.Runtime.getLocalizedInputStream(java.io.InputStream) definition code for java.lang.Runtime.getLocalizedInputStream(java.io.InputStream) (InputStream sample code for java.io.InputStream definition code for java.io.InputStream  in)
          Deprecated. As of JDK 1.1, the preferred way to translate a byte stream in the local encoding into a character stream in Unicode is via the InputStreamReader and BufferedReader classes.
 OutputStream sample code for java.io.OutputStream definition code for java.io.OutputStream getLocalizedOutputStream sample code for java.lang.Runtime.getLocalizedOutputStream(java.io.OutputStream) definition code for java.lang.Runtime.getLocalizedOutputStream(java.io.OutputStream) (OutputStream sample code for java.io.OutputStream definition code for java.io.OutputStream  out)
          Deprecated. As of JDK 1.1, the preferred way to translate a Unicode character stream into a byte stream in the local encoding is via the OutputStreamWriter, BufferedWriter, and PrintWriter classes.
static Runtime sample code for java.lang.Runtime definition code for java.lang.Runtime getRuntime sample code for java.lang.Runtime.getRuntime() definition code for java.lang.Runtime.getRuntime() ()
          Returns the runtime object associated with the current Java application.
 void halt sample code for java.lang.Runtime.halt(int) definition code for java.lang.Runtime.halt(int) (int status)
          Forcibly terminates the currently running Java virtual machine.
 void load sample code for java.lang.Runtime.load(java.lang.String) definition code for java.lang.Runtime.load(java.lang.String) (String sample code for java.lang.String definition code for java.lang.String  filename)
          Loads the specified filename as a dynamic library.
 void loadLibrary sample code for java.lang.Runtime.loadLibrary(java.lang.String) definition code for java.lang.Runtime.loadLibrary(java.lang.String) (String sample code for java.lang.String definition code for java.lang.String  libname)
          Loads the dynamic library with the specified library name.
 long maxMemory sample code for java.lang.Runtime.maxMemory() definition code for java.lang.Runtime.maxMemory() ()
          Returns the maximum amount of memory that the Java virtual machine will attempt to use.
 boolean removeShutdownHook sample code for java.lang.Runtime.removeShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.removeShutdownHook(java.lang.Thread) (Thread sample code for java.lang.Thread definition code for java.lang.Thread  hook)
          De-registers a previously-registered virtual-machine shutdown hook.
 void runFinalization sample code for java.lang.Runtime.runFinalization() definition code for java.lang.Runtime.runFinalization() ()
          Runs the finalization methods of any objects pending finalization.
static void runFinalizersOnExit sample code for java.lang.Runtime.runFinalizersOnExit(boolean) definition code for java.lang.Runtime.runFinalizersOnExit(boolean) (boolean value)
          Deprecated. This method is inherently unsafe. It may result in finalizers being called on live objects while other threads are concurrently manipulating those objects, resulting in erratic behavior or deadlock.
 long totalMemory sample code for java.lang.Runtime.totalMemory() definition code for java.lang.Runtime.totalMemory() ()
          Returns the total amount of memory in the Java virtual machine.
 void traceInstructions sample code for java.lang.Runtime.traceInstructions(boolean) definition code for java.lang.Runtime.traceInstructions(boolean) (boolean on)
          Enables/Disables tracing of instructions.
 void traceMethodCalls sample code for java.lang.Runtime.traceMethodCalls(boolean) definition code for java.lang.Runtime.traceMethodCalls(boolean) (boolean on)
          Enables/Disables tracing of method calls.
 
Methods inherited from class java.lang.Object sample code for java.lang.Object definition code for java.lang.Object
clone sample code for java.lang.Object.clone() definition code for java.lang.Object.clone() , equals sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) , finalize sample code for java.lang.Object.finalize() definition code for java.lang.Object.finalize() , getClass sample code for java.lang.Object.getClass() definition code for java.lang.Object.getClass() , hashCode sample code for java.lang.Object.hashCode() definition code for java.lang.Object.hashCode() , notify sample code for java.lang.Object.notify() definition code for java.lang.Object.notify() , notifyAll sample code for java.lang.Object.notifyAll() definition code for java.lang.Object.notifyAll() , toString sample code for java.lang.Object.toString() definition code for java.lang.Object.toString() , wait sample code for java.lang.Object.wait() definition code for java.lang.Object.wait() , wait sample code for java.lang.Object.wait(long) definition code for java.lang.Object.wait(long) , wait sample code for java.lang.Object.wait(long, int) definition code for java.lang.Object.wait(long, int)
 

Method Detail

getRuntime sample code for java.lang.Runtime.getRuntime() definition code for java.lang.Runtime.getRuntime()

public static Runtime sample code for java.lang.Runtime definition code for java.lang.Runtime  getRuntime()
Returns the runtime object associated with the current Java application. Most of the methods of class Runtime are instance methods and must be invoked with respect to the current runtime object.

Returns:
the Runtime object associated with the current Java application.

exit sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int)

public void exit(int status)
Terminates the currently running Java virtual machine by initiating its shutdown sequence. This method never returns normally. The argument serves as a status code; by convention, a nonzero status code indicates abnormal termination.

The virtual machine's shutdown sequence consists of two phases. In the first phase all registered shutdown hooks sample code for java.lang.Runtime.addShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.addShutdownHook(java.lang.Thread) , if any, are started in some unspecified order and allowed to run concurrently until they finish. In the second phase all uninvoked finalizers are run if finalization-on-exit sample code for java.lang.Runtime.runFinalizersOnExit(boolean) definition code for java.lang.Runtime.runFinalizersOnExit(boolean) has been enabled. Once this is done the virtual machine halts sample code for java.lang.Runtime.halt(int) definition code for java.lang.Runtime.halt(int) .

If this method is invoked after the virtual machine has begun its shutdown sequence then if shutdown hooks are being run this method will block indefinitely. If shutdown hooks have already been run and on-exit finalization has been enabled then this method halts the virtual machine with the given status code if the status is nonzero; otherwise, it blocks indefinitely.

The System.exit sample code for java.lang.System.exit(int) definition code for java.lang.System.exit(int) method is the conventional and convenient means of invoking this method.

Parameters:
status - Termination status. By convention, a nonzero status code indicates abnormal termination.
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager is present and its checkExit sample code for java.lang.SecurityManager.checkExit(int) definition code for java.lang.SecurityManager.checkExit(int) method does not permit exiting with the specified status
See Also:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException , SecurityManager.checkExit(int) sample code for java.lang.SecurityManager.checkExit(int) definition code for java.lang.SecurityManager.checkExit(int) , addShutdownHook(java.lang.Thread) sample code for java.lang.Runtime.addShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.addShutdownHook(java.lang.Thread) , removeShutdownHook(java.lang.Thread) sample code for java.lang.Runtime.removeShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.removeShutdownHook(java.lang.Thread) , runFinalizersOnExit(boolean) sample code for java.lang.Runtime.runFinalizersOnExit(boolean) definition code for java.lang.Runtime.runFinalizersOnExit(boolean) , halt(int) sample code for java.lang.Runtime.halt(int) definition code for java.lang.Runtime.halt(int)

addShutdownHook sample code for java.lang.Runtime.addShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.addShutdownHook(java.lang.Thread)

public void addShutdownHook(Thread sample code for java.lang.Thread definition code for java.lang.Thread  hook)
Registers a new virtual-machine shutdown hook.

The Java virtual machine shuts down in response to two kinds of events:

A shutdown hook is simply an initialized but unstarted thread. When the virtual machine begins its shutdown sequence it will start all registered shutdown hooks in some unspecified order and let them run concurrently. When all the hooks have finished it will then run all uninvoked finalizers if finalization-on-exit has been enabled. Finally, the virtual machine will halt. Note that daemon threads will continue to run during the shutdown sequence, as will non-daemon threads if shutdown was initiated by invoking the exit sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int) method.

Once the shutdown sequence has begun it can be stopped only by invoking the halt sample code for java.lang.Runtime.halt(int) definition code for java.lang.Runtime.halt(int) method, which forcibly terminates the virtual machine.

Once the shutdown sequence has begun it is impossible to register a new shutdown hook or de-register a previously-registered hook. Attempting either of these operations will cause an IllegalStateException sample code for java.lang.IllegalStateException definition code for java.lang.IllegalStateException to be thrown.

Shutdown hooks run at a delicate time in the life cycle of a virtual machine and should therefore be coded defensively. They should, in particular, be written to be thread-safe and to avoid deadlocks insofar as possible. They should also not rely blindly upon services that may have registered their own shutdown hooks and therefore may themselves in the process of shutting down.

Shutdown hooks should also finish their work quickly. When a program invokes exit sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int) the expectation is that the virtual machine will promptly shut down and exit. When the virtual machine is terminated due to user logoff or system shutdown the underlying operating system may only allow a fixed amount of time in which to shut down and exit. It is therefore inadvisable to attempt any user interaction or to perform a long-running computation in a shutdown hook.

Uncaught exceptions are handled in shutdown hooks just as in any other thread, by invoking the uncaughtException sample code for java.lang.ThreadGroup.uncaughtException(java.lang.Thread, java.lang.Throwable) definition code for java.lang.ThreadGroup.uncaughtException(java.lang.Thread, java.lang.Throwable) method of the thread's ThreadGroup sample code for java.lang.ThreadGroup definition code for java.lang.ThreadGroup object. The default implementation of this method prints the exception's stack trace to System.err sample code for java.lang.System.err definition code for java.lang.System.err and terminates the thread; it does not cause the virtual machine to exit or halt.

In rare circumstances the virtual machine may abort, that is, stop running without shutting down cleanly. This occurs when the virtual machine is terminated externally, for example with the SIGKILL signal on Unix or the TerminateProcess call on Microsoft Windows. The virtual machine may also abort if a native method goes awry by, for example, corrupting internal data structures or attempting to access nonexistent memory. If the virtual machine aborts then no guarantee can be made about whether or not any shutdown hooks will be run.

Parameters:
hook - An initialized but unstarted Thread sample code for java.lang.Thread definition code for java.lang.Thread object
Throws:
IllegalArgumentException sample code for java.lang.IllegalArgumentException definition code for java.lang.IllegalArgumentException - If the specified hook has already been registered, or if it can be determined that the hook is already running or has already been run
IllegalStateException sample code for java.lang.IllegalStateException definition code for java.lang.IllegalStateException - If the virtual machine is already in the process of shutting down
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager is present and it denies RuntimePermission sample code for java.lang.RuntimePermission definition code for java.lang.RuntimePermission ("shutdownHooks")
Since:
1.3
See Also:
removeShutdownHook(java.lang.Thread) sample code for java.lang.Runtime.removeShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.removeShutdownHook(java.lang.Thread) , halt(int) sample code for java.lang.Runtime.halt(int) definition code for java.lang.Runtime.halt(int) , exit(int) sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int)

removeShutdownHook sample code for java.lang.Runtime.removeShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.removeShutdownHook(java.lang.Thread)

public boolean removeShutdownHook(Thread sample code for java.lang.Thread definition code for java.lang.Thread  hook)
De-registers a previously-registered virtual-machine shutdown hook.

Parameters:
hook - the hook to remove
Returns:
true if the specified hook had previously been registered and was successfully de-registered, false otherwise.
Throws:
IllegalStateException sample code for java.lang.IllegalStateException definition code for java.lang.IllegalStateException - If the virtual machine is already in the process of shutting down
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager is present and it denies RuntimePermission sample code for java.lang.RuntimePermission definition code for java.lang.RuntimePermission ("shutdownHooks")
Since:
1.3
See Also:
addShutdownHook(java.lang.Thread) sample code for java.lang.Runtime.addShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.addShutdownHook(java.lang.Thread) , exit(int) sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int)

halt sample code for java.lang.Runtime.halt(int) definition code for java.lang.Runtime.halt(int)

public void halt(int status)
Forcibly terminates the currently running Java virtual machine. This method never returns normally.

This method should be used with extreme caution. Unlike the exit sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int) method, this method does not cause shutdown hooks to be started and does not run uninvoked finalizers if finalization-on-exit has been enabled. If the shutdown sequence has already been initiated then this method does not wait for any running shutdown hooks or finalizers to finish their work.

Parameters:
status - Termination status. By convention, a nonzero status code indicates abnormal termination. If the exit sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int) (equivalently, System.exit sample code for java.lang.System.exit(int) definition code for java.lang.System.exit(int) ) method has already been invoked then this status code will override the status code passed to that method.
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager is present and its checkExit sample code for java.lang.SecurityManager.checkExit(int) definition code for java.lang.SecurityManager.checkExit(int) method does not permit an exit with the specified status
Since:
1.3
See Also:
exit(int) sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int) , addShutdownHook(java.lang.Thread) sample code for java.lang.Runtime.addShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.addShutdownHook(java.lang.Thread) , removeShutdownHook(java.lang.Thread) sample code for java.lang.Runtime.removeShutdownHook(java.lang.Thread) definition code for java.lang.Runtime.removeShutdownHook(java.lang.Thread)

runFinalizersOnExit sample code for java.lang.Runtime.runFinalizersOnExit(boolean) definition code for java.lang.Runtime.runFinalizersOnExit(boolean)

@Deprecated
public static void runFinalizersOnExit(boolean value)
Deprecated. This method is inherently unsafe. It may result in finalizers being called on live objects while other threads are concurrently manipulating those objects, resulting in erratic behavior or deadlock.

Enable or disable finalization on exit; doing so specifies that the finalizers of all objects that have finalizers that have not yet been automatically invoked are to be run before the Java runtime exits. By default, finalization on exit is disabled.

If there is a security manager, its checkExit method is first called with 0 as its argument to ensure the exit is allowed. This could result in a SecurityException.

Parameters:
value - true to enable finalization on exit, false to disable
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - if a security manager exists and its checkExit method doesn't allow the exit.
Since:
JDK1.1
See Also:
exit(int) sample code for java.lang.Runtime.exit(int) definition code for java.lang.Runtime.exit(int) , gc() sample code for java.lang.Runtime.gc() definition code for java.lang.Runtime.gc() , SecurityManager.checkExit(int) sample code for java.lang.SecurityManager.checkExit(int) definition code for java.lang.SecurityManager.checkExit(int)

exec sample code for java.lang.Runtime.exec(java.lang.String) definition code for java.lang.Runtime.exec(java.lang.String)

public Process sample code for java.lang.Process definition code for java.lang.Process  exec(String sample code for java.lang.String definition code for java.lang.String  command)
             throws IOException sample code for java.io.IOException definition code for java.io.IOException 
Executes the specified string command in a separate process.

This is a convenience method. An invocation of the form exec(command) behaves in exactly the same way as the invocation exec sample code for java.lang.Runtime.exec(java.lang.String, java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String, java.lang.String[], java.io.File) (command, null, null).

Parameters:
command - a specified system command.
Returns:
A new Process sample code for java.lang.Process definition code for java.lang.Process object for managing the subprocess
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager exists and its checkExec sample code for java.lang.SecurityManager.checkExec(java.lang.String) definition code for java.lang.SecurityManager.checkExec(java.lang.String) method doesn't allow creation of the subprocess
IOException sample code for java.io.IOException definition code for java.io.IOException - If an I/O error occurs
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - If command is null
IllegalArgumentException sample code for java.lang.IllegalArgumentException definition code for java.lang.IllegalArgumentException - If command is empty
See Also:
exec(String[], String[], File) sample code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) , ProcessBuilder sample code for java.lang.ProcessBuilder definition code for java.lang.ProcessBuilder

exec sample code for java.lang.Runtime.exec(java.lang.String, java.lang.String[]) definition code for java.lang.Runtime.exec(java.lang.String, java.lang.String[])

public Process sample code for java.lang.Process definition code for java.lang.Process  exec(String sample code for java.lang.String definition code for java.lang.String  command,
                    String sample code for java.lang.String definition code for java.lang.String [] envp)
             throws IOException sample code for java.io.IOException definition code for java.io.IOException 
Executes the specified string command in a separate process with the specified environment.

This is a convenience method. An invocation of the form exec(command, envp) behaves in exactly the same way as the invocation exec sample code for java.lang.Runtime.exec(java.lang.String, java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String, java.lang.String[], java.io.File) (command, envp, null).

Parameters:
command - a specified system command.
envp - array of strings, each element of which has environment variable settings in the format name=value, or null if the subprocess should inherit the environment of the current process.
Returns:
A new Process sample code for java.lang.Process definition code for java.lang.Process object for managing the subprocess
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager exists and its checkExec sample code for java.lang.SecurityManager.checkExec(java.lang.String) definition code for java.lang.SecurityManager.checkExec(java.lang.String) method doesn't allow creation of the subprocess
IOException sample code for java.io.IOException definition code for java.io.IOException - If an I/O error occurs
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - If command is null, or one of the elements of envp is null
IllegalArgumentException sample code for java.lang.IllegalArgumentException definition code for java.lang.IllegalArgumentException - If command is empty
See Also:
exec(String[], String[], File) sample code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) , ProcessBuilder sample code for java.lang.ProcessBuilder definition code for java.lang.ProcessBuilder

exec sample code for java.lang.Runtime.exec(java.lang.String, java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String, java.lang.String[], java.io.File)

public Process sample code for java.lang.Process definition code for java.lang.Process  exec(String sample code for java.lang.String definition code for java.lang.String  command,
                    String sample code for java.lang.String definition code for java.lang.String [] envp,
                    File sample code for java.io.File definition code for java.io.File  dir)
             throws IOException sample code for java.io.IOException definition code for java.io.IOException 
Executes the specified string command in a separate process with the specified environment and working directory.

This is a convenience method. An invocation of the form exec(command, envp, dir) behaves in exactly the same way as the invocation exec sample code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) (cmdarray, envp, dir), where cmdarray is an array of all the tokens in command.

More precisely, the command string is broken into tokens using a StringTokenizer sample code for java.util.StringTokenizer definition code for java.util.StringTokenizer created by the call new StringTokenizer sample code for java.util.StringTokenizer definition code for java.util.StringTokenizer (command) with no further modification of the character categories. The tokens produced by the tokenizer are then placed in the new string array cmdarray, in the same order.

Parameters:
command - a specified system command.
envp - array of strings, each element of which has environment variable settings in the format name=value, or null if the subprocess should inherit the environment of the current process.
dir - the working directory of the subprocess, or null if the subprocess should inherit the working directory of the current process.
Returns:
A new Process sample code for java.lang.Process definition code for java.lang.Process object for managing the subprocess
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager exists and its checkExec sample code for java.lang.SecurityManager.checkExec(java.lang.String) definition code for java.lang.SecurityManager.checkExec(java.lang.String) method doesn't allow creation of the subprocess
IOException sample code for java.io.IOException definition code for java.io.IOException - If an I/O error occurs
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - If command is null, or one of the elements of envp is null
IllegalArgumentException sample code for java.lang.IllegalArgumentException definition code for java.lang.IllegalArgumentException - If command is empty
Since:
1.3
See Also:
ProcessBuilder sample code for java.lang.ProcessBuilder definition code for java.lang.ProcessBuilder

exec sample code for java.lang.Runtime.exec(java.lang.String[]) definition code for java.lang.Runtime.exec(java.lang.String[])

public Process sample code for java.lang.Process definition code for java.lang.Process  exec(String sample code for java.lang.String definition code for java.lang.String [] cmdarray)
             throws IOException sample code for java.io.IOException definition code for java.io.IOException 
Executes the specified command and arguments in a separate process.

This is a convenience method. An invocation of the form exec(cmdarray) behaves in exactly the same way as the invocation exec sample code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) (cmdarray, null, null).

Parameters:
cmdarray - array containing the command to call and its arguments.
Returns:
A new Process sample code for java.lang.Process definition code for java.lang.Process object for managing the subprocess
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager exists and its checkExec sample code for java.lang.SecurityManager.checkExec(java.lang.String) definition code for java.lang.SecurityManager.checkExec(java.lang.String) method doesn't allow creation of the subprocess
IOException sample code for java.io.IOException definition code for java.io.IOException - If an I/O error occurs
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - If cmdarray is null, or one of the elements of cmdarray is null
IndexOutOfBoundsException sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - If cmdarray is an empty array (has length 0)
See Also:
ProcessBuilder sample code for java.lang.ProcessBuilder definition code for java.lang.ProcessBuilder

exec sample code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[]) definition code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[])

public Process sample code for java.lang.Process definition code for java.lang.Process  exec(String sample code for java.lang.String definition code for java.lang.String [] cmdarray,
                    String sample code for java.lang.String definition code for java.lang.String [] envp)
             throws IOException sample code for java.io.IOException definition code for java.io.IOException 
Executes the specified command and arguments in a separate process with the specified environment.

This is a convenience method. An invocation of the form exec(cmdarray, envp) behaves in exactly the same way as the invocation exec sample code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) (cmdarray, envp, null).

Parameters:
cmdarray - array containing the command to call and its arguments.
envp - array of strings, each element of which has environment variable settings in the format name=value, or null if the subprocess should inherit the environment of the current process.
Returns:
A new Process sample code for java.lang.Process definition code for java.lang.Process object for managing the subprocess
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager exists and its checkExec sample code for java.lang.SecurityManager.checkExec(java.lang.String) definition code for java.lang.SecurityManager.checkExec(java.lang.String) method doesn't allow creation of the subprocess
IOException sample code for java.io.IOException definition code for java.io.IOException - If an I/O error occurs
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - If cmdarray is null, or one of the elements of cmdarray is null, or one of the elements of envp is null
IndexOutOfBoundsException sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - If cmdarray is an empty array (has length 0)
See Also:
ProcessBuilder sample code for java.lang.ProcessBuilder definition code for java.lang.ProcessBuilder

exec sample code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) definition code for java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File)

public Process sample code for java.lang.Process definition code for java.lang.Process  exec(String sample code for java.lang.String definition code for java.lang.String [] cmdarray,
                    String sample code for java.lang.String definition code for java.lang.String [] envp,
                    File sample code for java.io.File definition code for java.io.File  dir)
             throws IOException sample code for java.io.IOException definition code for java.io.IOException 
Executes the specified command and arguments in a separate process with the specified environment and working directory.

Given an array of strings cmdarray, representing the tokens of a command line, and an array of strings envp, representing "environment" variable settings, this method creates a new process in which to execute the specified command.

This method checks that cmdarray is a valid operating system command. Which commands are valid is system-dependent, but at the very least the command must be a non-empty list of non-null strings.

If envp is null, the subprocess inherits the environment settings of the current process.

ProcessBuilder.start() sample code for java.lang.ProcessBuilder.start() definition code for java.lang.ProcessBuilder.start() is now the preferred way to start a process with a modified environment.

The working directory of the new subprocess is specified by dir. If dir is null, the subprocess inherits the current working directory of the current process.

If a security manager exists, its checkExec sample code for java.lang.SecurityManager.checkExec(java.lang.String) definition code for java.lang.SecurityManager.checkExec(java.lang.String) method is invoked with the first component of the array cmdarray as its argument. This may result in a SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException being thrown.

Starting an operating system process is highly system-dependent. Among the many things that can go wrong are:

In such cases an exception will be thrown. The exact nature of the exception is system-dependent, but it will always be a subclass of IOException sample code for java.io.IOException definition code for java.io.IOException .

Parameters:
cmdarray - array containing the command to call and its arguments.
envp - array of strings, each element of which has environment variable settings in the format name=value, or null if the subprocess should inherit the environment of the current process.
dir - the working directory of the subprocess, or null if the subprocess should inherit the working directory of the current process.
Returns:
A new Process sample code for java.lang.Process definition code for java.lang.Process object for managing the subprocess
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - If a security manager exists and its checkExec sample code for java.lang.SecurityManager.checkExec(java.lang.String) definition code for java.lang.SecurityManager.checkExec(java.lang.String) method doesn't allow creation of the subprocess
IOException sample code for java.io.IOException definition code for java.io.IOException - If an I/O error occurs
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - If cmdarray is null, or one of the elements of cmdarray is null, or one of the elements of envp is null
IndexOutOfBoundsException sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - If cmdarray is an empty array (has length 0)
Since:
1.3
See Also:
ProcessBuilder sample code for java.lang.ProcessBuilder definition code for java.lang.ProcessBuilder

availableProcessors sample code for java.lang.Runtime.availableProcessors() definition code for java.lang.Runtime.availableProcessors()

public int availableProcessors()
Returns the number of processors available to the Java virtual machine.

This value may change during a particular invocation of the virtual machine. Applications that are sensitive to the number of available processors should therefore occasionally poll this property and adjust their resource usage appropriately.

Returns:
the maximum number of processors available to the virtual machine; never smaller than one
Since:
1.4

freeMemory sample code for java.lang.Runtime.freeMemory() definition code for java.lang.Runtime.freeMemory()

public long freeMemory()
Returns the amount of free memory in the Java Virtual Machine. Calling the gc method may result in increasing the value returned by freeMemory.

Returns:
an approximation to the total amount of memory currently available for future allocated objects, measured in bytes.

totalMemory sample code for java.lang.Runtime.totalMemory() definition code for java.lang.Runtime.totalMemory()

public long totalMemory()
Returns the total amount of memory in the Java virtual machine. The value returned by this method may vary over time, depending on the host environment.

Note that the amount of memory required to hold an object of any given type may be implementation-dependent.

Returns:
the total amount of memory currently available for current and future objects, measured in bytes.

maxMemory sample code for java.lang.Runtime.maxMemory() definition code for java.lang.Runtime.maxMemory()

public long maxMemory()
Returns the maximum amount of memory that the Java virtual machine will attempt to use. If there is no inherent limit then the value Long.MAX_VALUE sample code for java.lang.Long.MAX_VALUE definition code for java.lang.Long.MAX_VALUE will be returned.

Returns:
the maximum amount of memory that the virtual machine will attempt to use, measured in bytes
Since:
1.4

gc sample code for java.lang.Runtime.gc() definition code for java.lang.Runtime.gc()

public void gc()
Runs the garbage collector. Calling this method suggests that the Java virtual machine expend effort toward recycling unused objects in order to make the memory they currently occupy available for quick reuse. When control returns from the method call, the virtual machine has made its best effort to recycle all discarded objects.

The name gc stands for "garbage collector". The virtual machine performs this recycling process automatically as needed, in a separate thread, even if the gc method is not invoked explicitly.

The method System.gc() sample code for java.lang.System.gc() definition code for java.lang.System.gc() is the conventional and convenient means of invoking this method.


runFinalization sample code for java.lang.Runtime.runFinalization() definition code for java.lang.Runtime.runFinalization()

public void runFinalization()
Runs the finalization methods of any objects pending finalization. Calling this method suggests that the Java virtual machine expend effort toward running the finalize methods of objects that have been found to be discarded but whose finalize methods have not yet been run. When control returns from the method call, the virtual machine has made a best effort to complete all outstanding finalizations.

The virtual machine performs the finalization process automatically as needed, in a separate thread, if the runFinalization method is not invoked explicitly.

The method System.runFinalization() sample code for java.lang.System.runFinalization() definition code for java.lang.System.runFinalization() is the conventional and convenient means of invoking this method.

See Also:
Object.finalize() sample code for java.lang.Object.finalize() definition code for java.lang.Object.finalize()

traceInstructions sample code for java.lang.Runtime.traceInstructions(boolean) definition code for java.lang.Runtime.traceInstructions(boolean)

public void traceInstructions(boolean on)
Enables/Disables tracing of instructions. If the boolean argument is true, this method suggests that the Java virtual machine emit debugging information for each instruction in the virtual machine as it is executed. The format of this information, and the file or other output stream to which it is emitted, depends on the host environment. The virtual machine may ignore this request if it does not support this feature. The destination of the trace output is system dependent.

If the boolean argument is false, this method causes the virtual machine to stop performing the detailed instruction trace it is performing.

Parameters:
on - true to enable instruction tracing; false to disable this feature.

traceMethodCalls sample code for java.lang.Runtime.traceMethodCalls(boolean) definition code for java.lang.Runtime.traceMethodCalls(boolean)

public void traceMethodCalls(boolean on)
Enables/Disables tracing of method calls. If the boolean argument is true, this method suggests that the Java virtual machine emit debugging information for each method in the virtual machine as it is called. The format of this information, and the file or other output stream to which it is emitted, depends on the host environment. The virtual machine may ignore this request if it does not support this feature.

Calling this method with argument false suggests that the virtual machine cease emitting per-call debugging information.

Parameters:
on - true to enable instruction tracing; false to disable this feature.

load sample code for java.lang.Runtime.load(java.lang.String) definition code for java.lang.Runtime.load(java.lang.String)

public void load(String sample code for java.lang.String definition code for java.lang.String  filename)
Loads the specified filename as a dynamic library. The filename argument must be a complete path name. From java_g it will automagically insert "_g" before the ".so" (for example Runtime.getRuntime().load("/home/avh/lib/libX11.so");).

First, if there is a security manager, its checkLink method is called with the filename as its argument. This may result in a security exception.

This is similar to the method loadLibrary(String) sample code for java.lang.Runtime.loadLibrary(java.lang.String) definition code for java.lang.Runtime.loadLibrary(java.lang.String) , but it accepts a general file name as an argument rather than just a library name, allowing any file of native code to be loaded.

The method System.load(String) sample code for java.lang.System.load(java.lang.String) definition code for java.lang.System.load(java.lang.String) is the conventional and convenient means of invoking this method.

Parameters:
filename - the file to load.
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - if a security manager exists and its checkLink method doesn't allow loading of the specified dynamic library
UnsatisfiedLinkError sample code for java.lang.UnsatisfiedLinkError definition code for java.lang.UnsatisfiedLinkError - if the file does not exist.
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if filename is null
See Also:
getRuntime() sample code for java.lang.Runtime.getRuntime() definition code for java.lang.Runtime.getRuntime() , SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException , SecurityManager.checkLink(java.lang.String) sample code for java.lang.SecurityManager.checkLink(java.lang.String) definition code for java.lang.SecurityManager.checkLink(java.lang.String)

loadLibrary sample code for java.lang.Runtime.loadLibrary(java.lang.String) definition code for java.lang.Runtime.loadLibrary(java.lang.String)

public void loadLibrary(String sample code for java.lang.String definition code for java.lang.String  libname)
Loads the dynamic library with the specified library name. A file containing native code is loaded from the local file system from a place where library files are conventionally obtained. The details of this process are implementation-dependent. The mapping from a library name to a specific filename is done in a system-specific manner.

First, if there is a security manager, its checkLink method is called with the libname as its argument. This may result in a security exception.

The method System.loadLibrary(String) sample code for java.lang.System.loadLibrary(java.lang.String) definition code for java.lang.System.loadLibrary(java.lang.String) is the conventional and convenient means of invoking this method. If native methods are to be used in the implementation of a class, a standard strategy is to put the native code in a library file (call it LibFile) and then to put a static initializer:

 static { System.loadLibrary("LibFile"); }
 
within the class declaration. When the class is loaded and initialized, the necessary native code implementation for the native methods will then be loaded as well.

If this method is called more than once with the same library name, the second and subsequent calls are ignored.

Parameters:
libname - the name of the library.
Throws:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException - if a security manager exists and its checkLink method doesn't allow loading of the specified dynamic library
UnsatisfiedLinkError sample code for java.lang.UnsatisfiedLinkError definition code for java.lang.UnsatisfiedLinkError - if the library does not exist.
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if libname is null
See Also:
SecurityException sample code for java.lang.SecurityException definition code for java.lang.SecurityException , SecurityManager.checkLink(java.lang.String) sample code for java.lang.SecurityManager.checkLink(java.lang.String) definition code for java.lang.SecurityManager.checkLink(java.lang.String)

getLocalizedInputStream sample code for java.lang.Runtime.getLocalizedInputStream(java.io.InputStream) definition code for java.lang.Runtime.getLocalizedInputStream(java.io.InputStream)

@Deprecated
public InputStream sample code for java.io.InputStream definition code for java.io.InputStream  getLocalizedInputStream(InputStream sample code for java.io.InputStream definition code for java.io.InputStream  in)
Deprecated. As of JDK 1.1, the preferred way to translate a byte stream in the local encoding into a character stream in Unicode is via the InputStreamReader and BufferedReader classes.

Creates a localized version of an input stream. This method takes an InputStream and returns an InputStream equivalent to the argument in all respects except that it is localized: as characters in the local character set are read from the stream, they are automatically converted from the local character set to Unicode.

If the argument is already a localized stream, it may be returned as the result.

Parameters:
in - InputStream to localize
Returns:
a localized input stream
See Also:
InputStream sample code for java.io.InputStream definition code for java.io.InputStream , BufferedReader.BufferedReader(java.io.Reader) sample code for java.io.BufferedReader.BufferedReader(java.io.Reader) definition code for java.io.BufferedReader.BufferedReader(java.io.Reader) , InputStreamReader.InputStreamReader(java.io.InputStream) sample code for java.io.InputStreamReader.InputStreamReader(java.io.InputStream) definition code for java.io.InputStreamReader.InputStreamReader(java.io.InputStream)

getLocalizedOutputStream sample code for java.lang.Runtime.getLocalizedOutputStream(java.io.OutputStream) definition code for java.lang.Runtime.getLocalizedOutputStream(java.io.OutputStream)

@Deprecated
public OutputStream sample code for java.io.OutputStream definition code for java.io.OutputStream  getLocalizedOutputStream(OutputStream sample code for java.io.OutputStream definition code for java.io.OutputStream  out)
Deprecated. As of JDK 1.1, the preferred way to translate a Unicode character stream into a byte stream in the local encoding is via the OutputStreamWriter, BufferedWriter, and PrintWriter classes.

Creates a localized version of an output stream. This method takes an OutputStream and returns an OutputStream equivalent to the argument in all respects except that it is localized: as Unicode characters are written to the stream, they are automatically converted to the local character set.

If the argument is already a localized stream, it may be returned as the result.

Parameters:
out - OutputStream to localize
Returns:
a localized output stream
See Also:
OutputStream sample code for java.io.OutputStream definition code for java.io.OutputStream , BufferedWriter.BufferedWriter(java.io.Writer) sample code for java.io.BufferedWriter.BufferedWriter(java.io.Writer) definition code for java.io.BufferedWriter.BufferedWriter(java.io.Writer) , OutputStreamWriter.OutputStreamWriter(java.io.OutputStream) sample code for java.io.OutputStreamWriter.OutputStreamWriter(java.io.OutputStream) definition code for java.io.OutputStreamWriter.OutputStreamWriter(java.io.OutputStream) , PrintWriter.PrintWriter(java.io.OutputStream) sample code for java.io.PrintWriter.PrintWriter(java.io.OutputStream) definition code for java.io.PrintWriter.PrintWriter(java.io.OutputStream)