/* * @(#)Thread.java 1.125 01/12/03 * * Copyright 2002 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.lang; import java.security.AccessController; import java.security.AccessControlContext; import java.util.Map; import java.util.Collections; import sun.nio.ch.Interruptible; //@import java.nio.channels.ClosedByInterruptException; /** * JSR166: Added UncaughtExceptionHandlers, removeAllThreadLocals.

* A thread is a thread of execution in a program. The Java * Virtual Machine allows an application to have multiple threads of * execution running concurrently. *

* Every thread has a priority. Threads with higher priority are * executed in preference to threads with lower priority. Each thread * may or may not also be marked as a daemon. When code running in * some thread creates a new Thread object, the new * thread has its priority initially set equal to the priority of the * creating thread, and is a daemon thread if and only if the * creating thread is a daemon. *

* When a Java Virtual Machine starts up, there is usually a single * non-daemon thread (which typically calls the method named * main of some designated class). The Java Virtual * Machine continues to execute threads until either of the following * occurs: *

*

* There are two ways to create a new thread of execution. One is to * declare a class to be a subclass of Thread. This * subclass should override the run method of class * Thread. An instance of the subclass can then be * allocated and started. For example, a thread that computes primes * larger than a stated value could be written as follows: * 

 *     class PrimeThread extends Thread {
 *         long minPrime;
 *         PrimeThread(long minPrime) {
 *             this.minPrime = minPrime;
 *         }
 * 
 *         public void run() {
 *             // compute primes larger than minPrime
 *              . . .
 *         }
 *     }
 *
*

* The following code would then create a thread and start it running: * 

 *     PrimeThread p = new PrimeThread(143);
 *     p.start();
 *
*

* The other way to create a thread is to declare a class that * implements the Runnable interface. That class then * implements the run method. An instance of the class can * then be allocated, passed as an argument when creating * Thread, and started. The same example in this other * style looks like the following: * 

 *     class PrimeRun implements Runnable {
 *         long minPrime;
 *         PrimeRun(long minPrime) {
 *             this.minPrime = minPrime;
 *         }
 * 
 *         public void run() {
 *             // compute primes larger than minPrime
 *              . . .
 *         }
 *     }
 *
*

* The following code would then create a thread and start it running: * 

 *     PrimeRun p = new PrimeRun(143);
 *     new Thread(p).start();
 *
*

* Every thread has a name for identification purposes. More than * one thread may have the same name. If a name is not specified when * a thread is created, a new name is generated for it. * * @author unascribed * @version 1.125, 12/03/01 * @see java.lang.Runnable * @see java.lang.Runtime#exit(int) * @see java.lang.Thread#run() * @see java.lang.Thread#stop() * @since JDK1.0 */ public class Thread implements Runnable { /** * Interface for handlers invoked when a Thread abruptly terminates * due to an uncaught exception. */ public interface UncaughtExceptionHandler { // jsr166 void uncaughtException(Thread t, Throwable e); } private static UncaughtExceptionHandler defaultUncaughtExceptionHandler; // jsr166 /** * Set the default handler invoked when a Thread abruptly terminates * due to an uncaught exception. If unset or set to null, a * Thread's ThreadGroup serves as the default handler. * @exception SecurityException if the current thread is not allowed to * current thread. */ public static void setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler eh) { // jsr166 currentThread().checkAccess(); defaultUncaughtExceptionHandler = eh; } /** * Return the default handler invoked when a Thread abruptly terminates * due to an uncaught exception. */ public static UncaughtExceptionHandler getDefaultUncaughtExceptionHandler() { // jsr166 return defaultUncaughtExceptionHandler; } /** * Return the handler invoked when this Thread abruptly terminates * due to an uncaught exception. */ public UncaughtExceptionHandler getUncaughtExceptionHandler() { // jsr166 return (uncaughtExceptionHandler != null)? uncaughtExceptionHandler : group; } /** * Set the handler invoked when this Thread abruptly terminates * due to an uncaught exception. * @exception SecurityException if the current thread is not allowed to * modify current thread. */ public void setUncaughtExceptionHandler (UncaughtExceptionHandler eh) { // jsr166 checkAccess(); uncaughtExceptionHandler = eh; } /** * Remove all values associated with ThreadLocals and * InheritableThreadLocals for this thread. This method is * designed to be used only in Thread Pools and related contexts * in which a thread is reused to perform several unrelated tasks. * @exception SecurityException if the current thread is not allowed to * modify current thread. */ public static void removeAllThreadLocals() { // jsr166 Thread t = currentThread(); t.checkAccess(); t.threadLocals = null; t.inheritableThreadLocals = null; } /* Make sure registerNatives is the first thing does. */ private static native void registerNatives(); static { registerNatives(); } private char name[]; private int priority; private Thread threadQ; private long eetop; private UncaughtExceptionHandler uncaughtExceptionHandler; // jsr166 /* Whether or not to single_step this thread. */ private boolean single_step; /* Whether or not the thread is a daemon thread. */ private boolean daemon = false; /* Whether or not this thread was asked to exit before it runs.*/ private boolean stillborn = false; /* What will be run. */ private Runnable target; /* The group of this thread */ private ThreadGroup group; /* The context ClassLoader for this thread */ private ClassLoader contextClassLoader; /* The inherited AccessControlContext of this thread */ private AccessControlContext inheritedAccessControlContext; /* For autonumbering anonymous threads. */ private static int threadInitNumber; private static synchronized int nextThreadNum() { return threadInitNumber++; } // static permissions private static RuntimePermission stopThreadPermission; /* ThreadLocal values pertaining to this thread. This map is maintained * by the ThreadLocal class. */ ThreadLocal.ThreadLocalMap threadLocals = null; /* * InheritableThreadLocal values pertaining to this thread. This map is * maintained by the InheritableThreadLocal class. */ ThreadLocal.ThreadLocalMap inheritableThreadLocals = null; /* * The requested stack size for this thread, or 0 if the creator did * not specify a stack size. It is up to the VM to do whatever it * likes with this number; some VMs will ignore it. */ private long stackSize; /* The object in which this thread is blocked in an interruptible I/O * operation, if any. The blocker's interrupt method() should be invoked * before setting this thread's interrupt status. */ private volatile Interruptible blocker; /* Set the blocker field; invoked via reflection magic from java.nio code */ private void blockedOn(Interruptible b) { blocker = b; } /** * The minimum priority that a thread can have. */ public final static int MIN_PRIORITY = 1; /** * The default priority that is assigned to a thread. */ public final static int NORM_PRIORITY = 5; /** * The maximum priority that a thread can have. */ public final static int MAX_PRIORITY = 10; /** * Returns a reference to the currently executing thread object. * * @return the currently executing thread. */ public static native Thread currentThread(); /** * Causes the currently executing thread object to temporarily pause * and allow other threads to execute. */ public static native void yield(); /** * Causes the currently executing thread to sleep (temporarily cease * execution) for the specified number of milliseconds. The thread * does not lose ownership of any monitors. * * @param millis the length of time to sleep in milliseconds. * @exception InterruptedException if another thread has interrupted * the current thread. The interrupted status of the * current thread is cleared when this exception is thrown. * @see java.lang.Object#notify() */ public static native void sleep(long millis) throws InterruptedException; /** * Causes the currently executing thread to sleep (cease execution) * for the specified number of milliseconds plus the specified number * of nanoseconds. The thread does not lose ownership of any monitors. * * @param millis the length of time to sleep in milliseconds. * @param nanos 0-999999 additional nanoseconds to sleep. * @exception IllegalArgumentException if the value of millis is * negative or the value of nanos is not in the range * 0-999999. * @exception InterruptedException if another thread has interrupted * the current thread. The interrupted status of the * current thread is cleared when this exception is thrown. * @see java.lang.Object#notify() */ public static void sleep(long millis, int nanos) throws InterruptedException { if (millis < 0) { throw new IllegalArgumentException("timeout value is negative"); } if (nanos < 0 || nanos > 999999) { throw new IllegalArgumentException( "nanosecond timeout value out of range"); } if (nanos >= 500000 || (nanos != 0 && millis == 0)) { millis++; } sleep(millis); } /** * Initialize a Thread. * * @param g the Thread group * @param target the object whose run() method gets called * @param name the name of the new Thread * @param stackSize the desired stack size for the new thread, or * zero to indicate that this parameter is to be ignored. */ private void init(ThreadGroup g, Runnable target, String name, long stackSize) { Thread parent = currentThread(); if (g == null) { /* Determine if it's an applet or not */ SecurityManager security = System.getSecurityManager(); /* If there is a security manager, ask the security manager what to do. */ if (security != null) { g = security.getThreadGroup(); } /* If the security doesn't have a strong opinion of the matter use the parent thread group. */ if (g == null) { g = parent.getThreadGroup(); } } /* checkAccess regardless of whether or not threadgroup is explicitly passed in. */ g.checkAccess(); this.group = g; this.daemon = parent.isDaemon(); this.priority = parent.getPriority(); this.name = name.toCharArray(); this.contextClassLoader = parent.contextClassLoader; this.inheritedAccessControlContext = AccessController.getContext(); this.target = target; setPriority(priority); if (parent.inheritableThreadLocals != null) this.inheritableThreadLocals = ThreadLocal.createInheritedMap(parent.inheritableThreadLocals); /* Stash the specified stack size in case the VM cares */ this.stackSize = stackSize; g.add(this); } /** * Allocates a new Thread object. This constructor has * the same effect as Thread(null, null, * gname), where gname is * a newly generated name. Automatically generated names are of the * form "Thread-"+n, where n is an integer. * * @see java.lang.Thread#Thread(java.lang.ThreadGroup, * java.lang.Runnable, java.lang.String) */ public Thread() { init(null, null, "Thread-" + nextThreadNum(), 0); } /** * Allocates a new Thread object. This constructor has * the same effect as Thread(null, target, * gname), where gname is * a newly generated name. Automatically generated names are of the * form "Thread-"+n, where n is an integer. * * @param target the object whose run method is called. * @see java.lang.Thread#Thread(java.lang.ThreadGroup, * java.lang.Runnable, java.lang.String) */ public Thread(Runnable target) { init(null, target, "Thread-" + nextThreadNum(), 0); } /** * Allocates a new Thread object. This constructor has * the same effect as Thread(group, target, * gname), where gname is * a newly generated name. Automatically generated names are of the * form "Thread-"+n, where n is an integer. * * @param group the thread group. * @param target the object whose run method is called. * @exception SecurityException if the current thread cannot create a * thread in the specified thread group. * @see java.lang.Thread#Thread(java.lang.ThreadGroup, * java.lang.Runnable, java.lang.String) */ public Thread(ThreadGroup group, Runnable target) { init(group, target, "Thread-" + nextThreadNum(), 0); } /** * Allocates a new Thread object. This constructor has * the same effect as Thread(null, null, name). * * @param name the name of the new thread. * @see java.lang.Thread#Thread(java.lang.ThreadGroup, * java.lang.Runnable, java.lang.String) */ public Thread(String name) { init(null, null, name, 0); } /** * Allocates a new Thread object. This constructor has * the same effect as Thread(group, null, name) * * @param group the thread group. * @param name the name of the new thread. * @exception SecurityException if the current thread cannot create a * thread in the specified thread group. * @see java.lang.Thread#Thread(java.lang.ThreadGroup, * java.lang.Runnable, java.lang.String) */ public Thread(ThreadGroup group, String name) { init(group, null, name, 0); } /** * Allocates a new Thread object. This constructor has * the same effect as Thread(null, target, name). * * @param target the object whose run method is called. * @param name the name of the new thread. * @see java.lang.Thread#Thread(java.lang.ThreadGroup, * java.lang.Runnable, java.lang.String) */ public Thread(Runnable target, String name) { init(null, target, name, 0); } /** * Allocates a new Thread object so that it has * target as its run object, has the specified * name as its name, and belongs to the thread group * referred to by group. *

* If group is null and there is a * security manager, the group is determined by the security manager's * getThreadGroup method. If group is * null and there is not a security manager, or the * security manager's getThreadGroup method returns * null, the group is set to be the same ThreadGroup * as the thread that is creating the new thread. * *

If there is a security manager, its checkAccess * method is called with the ThreadGroup as its argument. * This may result in a SecurityException. *

* If the target argument is not null, the * run method of the target is called when * this thread is started. If the target argument is * null, this thread's run method is called * when this thread is started. *

* The priority of the newly created thread is set equal to the * priority of the thread creating it, that is, the currently running * thread. The method setPriority may be used to * change the priority to a new value. *

* The newly created thread is initially marked as being a daemon * thread if and only if the thread creating it is currently marked * as a daemon thread. The method setDaemon may be used * to change whether or not a thread is a daemon. * * @param group the thread group. * @param target the object whose run method is called. * @param name the name of the new thread. * @exception SecurityException if the current thread cannot create a * thread in the specified thread group. * @see java.lang.Runnable#run() * @see java.lang.Thread#run() * @see java.lang.Thread#setDaemon(boolean) * @see java.lang.Thread#setPriority(int) * @see java.lang.ThreadGroup#checkAccess() * @see SecurityManager#checkAccess */ public Thread(ThreadGroup group, Runnable target, String name) { init(group, target, name, 0); } /** * Allocates a new Thread object so that it has * target as its run object, has the specified * name as its name, belongs to the thread group referred to * by group, and has the specified stack size. * *

This constructor is identical to {@link * #Thread(ThreadGroup,Runnable,String)} with the exception of the fact * that it allows the thread stack size to be specified. The stack size * is the approximate number of bytes of address space that the virtual * machine is to allocate for this thread's stack. The effect of the * stackSize parameter, if any, is highly platform dependent. * *

On some platforms, specifying a higher value for the * stackSize parameter may allow a thread to achieve greater * recursion depth before throwing a {@link StackOverflowError}. * Similarly, specifying a lower value may allow a greater number of * threads to exist concurrently without throwing an an {@link * OutOfMemoryError} (or other internal error). The details of * the relationship between the value of the stackSize parameter * and the maximum recursion depth and concurrency level are * platform-dependent. On some platforms, the value of the * stackSize parameter may have no effect whatsoever. * *

The virtual machine is free to treat the stackSize * parameter as a suggestion. If the specified value is unreasonably low * for the platform, the virtual machine may instead use some * platform-specific minimum value; if the specified value is unreasonably * high, the virtual machine may instead use some platform-specific * maximum. Likewise, the virtual machine is free to round the specified * value up or down as it sees fit (or to ignore it completely). * *

Specifying a value of zero for the stackSize parameter will * cause this constructor to behave exactly like the * Thread(ThreadGroup, Runnable, String) constructor. * *

Due to the platform-dependent nature of the behavior of this * constructor, extreme care should be exercised in its use. * The thread stack size necessary to perform a given computation will * likely vary from one JRE implementation to another. In light of this * variation, careful tuning of the stack size parameter may be required, * and the tuning may need to be repeated for each JRE implementation on * which an application is to run. * *

Implementation note: Java platform implementers are encouraged to * document their implementation's behavior with respect to the * stackSize parameter. * * @param group the thread group. * @param target the object whose run method is called. * @param name the name of the new thread. * @param stackSize the desired stack size for the new thread, or * zero to indicate that this parameter is to be ignored. * @exception SecurityException if the current thread cannot create a * thread in the specified thread group. */ public Thread(ThreadGroup group, Runnable target, String name, long stackSize) { init(group, target, name, stackSize); } /** * Causes this thread to begin execution; the Java Virtual Machine * calls the run method of this thread. *

* The result is that two threads are running concurrently: the * current thread (which returns from the call to the * start method) and the other thread (which executes its * run method). * * @exception IllegalThreadStateException if the thread was already * started. * @see java.lang.Thread#run() * @see java.lang.Thread#stop() */ public synchronized native void start(); /** * If this thread was constructed using a separate * Runnable run object, then that * Runnable object's run method is called; * otherwise, this method does nothing and returns. *

* Subclasses of Thread should override this method. * * @see java.lang.Thread#start() * @see java.lang.Thread#stop() * @see java.lang.Thread#Thread(java.lang.ThreadGroup, * java.lang.Runnable, java.lang.String) * @see java.lang.Runnable#run() */ public void run() { if (target != null) { target.run(); } } /** * This method is called by the system to give a Thread * a chance to clean up before it actually exits. */ private void exit() { if (group != null) { group.remove(this); group = null; } /* Aggressively null object connected to Thread: see bug 4006245 */ target = null; } /** * Forces the thread to stop executing. *

* If there is a security manager installed, its checkAccess * method is called with this * as its argument. This may result in a * SecurityException being raised (in the current thread). *

* If this thread is different from the current thread (that is, the current * thread is trying to stop a thread other than itself), the * security manager's checkPermission method (with a * RuntimePermission("stopThread") argument) is called in * addition. * Again, this may result in throwing a * SecurityException (in the current thread). *

* The thread represented by this thread is forced to stop whatever * it is doing abnormally and to throw a newly created * ThreadDeath object as an exception. *

* It is permitted to stop a thread that has not yet been started. * If the thread is eventually started, it immediately terminates. *

* An application should not normally try to catch * ThreadDeath unless it must do some extraordinary * cleanup operation (note that the throwing of * ThreadDeath causes finally clauses of * try statements to be executed before the thread * officially dies). If a catch clause catches a * ThreadDeath object, it is important to rethrow the * object so that the thread actually dies. *

* The top-level error handler that reacts to otherwise uncaught * exceptions does not print out a message or otherwise notify the * application if the uncaught exception is an instance of * ThreadDeath. * * @exception SecurityException if the current thread cannot * modify this thread. * @see java.lang.Thread#interrupt() * @see java.lang.Thread#checkAccess() * @see java.lang.Thread#run() * @see java.lang.Thread#start() * @see java.lang.ThreadDeath * @see java.lang.ThreadGroup#uncaughtException(java.lang.Thread, * java.lang.Throwable) * @see SecurityManager#checkAccess(Thread) * @see SecurityManager#checkPermission * @deprecated This method is inherently unsafe. Stopping a thread with * Thread.stop causes it to unlock all of the monitors that it * has locked (as a natural consequence of the unchecked * ThreadDeath exception propagating up the stack). If * any of the objects previously protected by these monitors were in * an inconsistent state, the damaged objects become visible to * other threads, potentially resulting in arbitrary behavior. Many * uses of stop should be replaced by code that simply * modifies some variable to indicate that the target thread should * stop running. The target thread should check this variable * regularly, and return from its run method in an orderly fashion * if the variable indicates that it is to stop running. If the * target thread waits for long periods (on a condition variable, * for example), the interrupt method should be used to * interrupt the wait. * For more information, see * Why * are Thread.stop, Thread.suspend and Thread.resume Deprecated?. */ public final void stop() { synchronized (this) { //if the thread is alreay dead, return if (!this.isAlive()) return; SecurityManager security = System.getSecurityManager(); if (security != null) { checkAccess(); if (this != Thread.currentThread()) { if (stopThreadPermission == null) stopThreadPermission = new RuntimePermission("stopThread"); security.checkPermission(stopThreadPermission); } } resume(); // Wake up thread if it was suspended; no-op otherwise stop0(new ThreadDeath()); } } /** * Forces the thread to stop executing. *

* If there is a security manager installed, the checkAccess * method of this thread is called, which may result in a * SecurityException being raised (in the current thread). *

* If this thread is different from the current thread (that is, the current * thread is trying to stop a thread other than itself) or * obj is not an instance of ThreadDeath, the * security manager's checkPermission method (with the * RuntimePermission("stopThread") argument) is called in * addition. * Again, this may result in throwing a * SecurityException (in the current thread). *

* If the argument obj is null, a * NullPointerException is thrown (in the current thread). *

* The thread represented by this thread is forced to complete * whatever it is doing abnormally and to throw the * Throwable object obj as an exception. This * is an unusual action to take; normally, the stop method * that takes no arguments should be used. *

* It is permitted to stop a thread that has not yet been started. * If the thread is eventually started, it immediately terminates. * * @param obj the Throwable object to be thrown. * @exception SecurityException if the current thread cannot modify * this thread. * @see java.lang.Thread#interrupt() * @see java.lang.Thread#checkAccess() * @see java.lang.Thread#run() * @see java.lang.Thread#start() * @see java.lang.Thread#stop() * @see SecurityManager#checkAccess(Thread) * @see SecurityManager#checkPermission * @deprecated This method is inherently unsafe. See {@link #stop} * (with no arguments) for details. An additional danger of this * method is that it may be used to generate exceptions that the * target thread is unprepared to handle (including checked * exceptions that the thread could not possibly throw, were it * not for this method). * For more information, see * Why * are Thread.stop, Thread.suspend and Thread.resume Deprecated?. */ public final synchronized void stop(Throwable obj) { SecurityManager security = System.getSecurityManager(); if (security != null) { checkAccess(); if ((this != Thread.currentThread()) || (!(obj instanceof ThreadDeath))) { if (stopThreadPermission == null) stopThreadPermission = new RuntimePermission("stopThread"); security.checkPermission(stopThreadPermission); } } resume(); // Wake up thread if it was suspended; no-op otherwise stop0(obj); } /** * Interrupts this thread. * *

First the {@link #checkAccess() checkAccess} method of this thread * is invoked, which may cause a {@link SecurityException} to be thrown. * *

If this thread is blocked in an invocation of the {@link * Object#wait() wait()}, {@link Object#wait(long) wait(long)}, or {@link * Object#wait(long, int) wait(long, int)} methods of the {@link Object} * class, or of the {@link #join()}, {@link #join(long)}, {@link * #join(long, int)}, {@link #sleep(long)}, or {@link #sleep(long, int)}, * methods of this class, then its interrupt status will be cleared and it * will receive an {@link InterruptedException}. * *

If this thread is blocked in an I/O operation upon an {@link * java.nio.channels.InterruptibleChannel interruptible * channel} then the channel will be closed, the thread's interrupt * status will be set, and the thread will receive a {@link * java.nio.channels.ClosedByInterruptException}. * *

If this thread is blocked in a {@link java.nio.channels.Selector} * then the thread's interrupt status will be set and it will return * immediately from the selection operation, possibly with a non-zero * value, just as if the selector's {@link * java.nio.channels.Selector#wakeup wakeup} method were invoked. * *

If none of the previous conditions hold then this thread's interrupt * status will be set.

* * @throws SecurityException * if the current thread cannot modify this thread * * @revised 1.4 * @spec JSR-51 */ public void interrupt() { checkAccess(); Interruptible b = blocker; if (b != null) { b.interrupt(); } interrupt0(); } /** * Tests whether the current thread has been interrupted. The * interrupted status of the thread is cleared by this method. In * other words, if this method were to be called twice in succession, the * second call would return false (unless the current thread were * interrupted again, after the first call had cleared its interrupted * status and before the second call had examined it). * * @return true if the current thread has been interrupted; * false otherwise. * @see java.lang.Thread#isInterrupted() */ public static boolean interrupted() { return currentThread().isInterrupted(true); } /** * Tests whether this thread has been interrupted. The interrupted * status of the thread is unaffected by this method. * * @return true if this thread has been interrupted; * false otherwise. * @see java.lang.Thread#interrupted() */ public boolean isInterrupted() { return isInterrupted(false); } /** * Tests if some Thread has been interrupted. The interrupted state * is reset or not based on the value of ClearInterrupted that is * passed. */ private native boolean isInterrupted(boolean ClearInterrupted); /** * Destroys this thread, without any cleanup. Any monitors it has * locked remain locked. (This method is not implemented.) */ public void destroy() { throw new NoSuchMethodError(); } /** * Tests if this thread is alive. A thread is alive if it has * been started and has not yet died. * * @return true if this thread is alive; * false otherwise. */ public final native boolean isAlive(); /** * Suspends this thread. *

* First, the checkAccess method of this thread is called * with no arguments. This may result in throwing a * SecurityException (in the current thread). *

* If the thread is alive, it is suspended and makes no further * progress unless and until it is resumed. * * @exception SecurityException if the current thread cannot modify * this thread. * @see #checkAccess * @deprecated This method has been deprecated, as it is * inherently deadlock-prone. If the target thread holds a lock on the * monitor protecting a critical system resource when it is suspended, no * thread can access this resource until the target thread is resumed. If * the thread that would resume the target thread attempts to lock this * monitor prior to calling resume, deadlock results. Such * deadlocks typically manifest themselves as "frozen" processes. * For more information, see * Why * are Thread.stop, Thread.suspend and Thread.resume Deprecated?. */ public final void suspend() { checkAccess(); suspend0(); } /** * Resumes a suspended thread. *

* First, the checkAccess method of this thread is called * with no arguments. This may result in throwing a * SecurityException (in the current thread). *

* If the thread is alive but suspended, it is resumed and is * permitted to make progress in its execution. * * @exception SecurityException if the current thread cannot modify this * thread. * @see #checkAccess * @see java.lang.Thread#suspend() * @deprecated This method exists solely for use with {@link #suspend}, * which has been deprecated because it is deadlock-prone. * For more information, see * Why * are Thread.stop, Thread.suspend and Thread.resume Deprecated?. */ public final void resume() { checkAccess(); resume0(); } /** * Changes the priority of this thread. *

* First the checkAccess method of this thread is called * with no arguments. This may result in throwing a * SecurityException. *

* Otherwise, the priority of this thread is set to the smaller of * the specified newPriority and the maximum permitted * priority of the thread's thread group. * * @param newPriority priority to set this thread to * @exception IllegalArgumentException If the priority is not in the * range MIN_PRIORITY to * MAX_PRIORITY. * @exception SecurityException if the current thread cannot modify * this thread. * @see #getPriority * @see java.lang.Thread#checkAccess() * @see java.lang.Thread#getPriority() * @see java.lang.Thread#getThreadGroup() * @see java.lang.Thread#MAX_PRIORITY * @see java.lang.Thread#MIN_PRIORITY * @see java.lang.ThreadGroup#getMaxPriority() */ public final void setPriority(int newPriority) { checkAccess(); if (newPriority > MAX_PRIORITY || newPriority < MIN_PRIORITY) { throw new IllegalArgumentException(); } if (newPriority > group.getMaxPriority()) { newPriority = group.getMaxPriority(); } setPriority0(priority = newPriority); } /** * Returns this thread's priority. * * @return this thread's priority. * @see #setPriority * @see java.lang.Thread#setPriority(int) */ public final int getPriority() { return priority; } /** * Changes the name of this thread to be equal to the argument * name. *

* First the checkAccess method of this thread is called * with no arguments. This may result in throwing a * SecurityException. * * @param name the new name for this thread. * @exception SecurityException if the current thread cannot modify this * thread. * @see #getName * @see java.lang.Thread#checkAccess() * @see java.lang.Thread#getName() */ public final void setName(String name) { checkAccess(); this.name = name.toCharArray(); } /** * Returns this thread's name. * * @return this thread's name. * @see #setName * @see java.lang.Thread#setName(java.lang.String) */ public final String getName() { return String.valueOf(name); } /** * Returns the thread group to which this thread belongs. * This method returns null if this thread has died * (been stopped). * * @return this thread's thread group. */ public final ThreadGroup getThreadGroup() { return group; } /** * Returns the number of active threads in the current thread's thread * group. * * @return the number of active threads in the current thread's thread * group. */ public static int activeCount() { return currentThread().getThreadGroup().activeCount(); } /** * Copies into the specified array every active thread in * the current thread's thread group and its subgroups. This method simply * calls the enumerate method of the current thread's thread * group with the array argument. *

* First, if there is a security manager, that enumerate * method calls the security * manager's checkAccess method * with the thread group as its argument. This may result * in throwing a SecurityException. * * @param tarray an array of Thread objects to copy to * @return the number of threads put into the array * @exception SecurityException if a security manager exists and its * checkAccess method doesn't allow the operation. * @see java.lang.ThreadGroup#enumerate(java.lang.Thread[]) * @see java.lang.SecurityManager#checkAccess(java.lang.ThreadGroup) */ public static int enumerate(Thread tarray[]) { return currentThread().getThreadGroup().enumerate(tarray); } /** * Counts the number of stack frames in this thread. The thread must * be suspended. * * @return the number of stack frames in this thread. * @exception IllegalThreadStateException if this thread is not * suspended. * @deprecated The definition of this call depends on {@link #suspend}, * which is deprecated. Further, the results of this call * were never well-defined. */ public native int countStackFrames(); /** * Waits at most millis milliseconds for this thread to * die. A timeout of 0 means to wait forever. * * @param millis the time to wait in milliseconds. * @exception InterruptedException if another thread has interrupted * the current thread. The interrupted status of the * current thread is cleared when this exception is thrown. */ public final synchronized void join(long millis) throws InterruptedException { long base = System.currentTimeMillis(); long now = 0; if (millis < 0) { throw new IllegalArgumentException("timeout value is negative"); } if (millis == 0) { while (isAlive()) { wait(0); } } else { while (isAlive()) { long delay = millis - now; if (delay <= 0) { break; } wait(delay); now = System.currentTimeMillis() - base; } } } /** * Waits at most millis milliseconds plus * nanos nanoseconds for this thread to die. * * @param millis the time to wait in milliseconds. * @param nanos 0-999999 additional nanoseconds to wait. * @exception IllegalArgumentException if the value of millis is negative * the value of nanos is not in the range 0-999999. * @exception InterruptedException if another thread has interrupted * the current thread. The interrupted status of the * current thread is cleared when this exception is thrown. */ public final synchronized void join(long millis, int nanos) throws InterruptedException { if (millis < 0) { throw new IllegalArgumentException("timeout value is negative"); } if (nanos < 0 || nanos > 999999) { throw new IllegalArgumentException( "nanosecond timeout value out of range"); } if (nanos >= 500000 || (nanos != 0 && millis == 0)) { millis++; } join(millis); } /** * Waits for this thread to die. * * @exception InterruptedException if another thread has interrupted * the current thread. The interrupted status of the * current thread is cleared when this exception is thrown. */ public final void join() throws InterruptedException { join(0); } /** * Prints a stack trace of the current thread. This method is used * only for debugging. * * @see java.lang.Throwable#printStackTrace() */ public static void dumpStack() { new Exception("Stack trace").printStackTrace(); } /** * Marks this thread as either a daemon thread or a user thread. The * Java Virtual Machine exits when the only threads running are all * daemon threads. *

* This method must be called before the thread is started. *

* This method first calls the checkAccess method * of this thread * with no arguments. This may result in throwing a * SecurityException (in the current thread). * * @param on if true, marks this thread as a * daemon thread. * @exception IllegalThreadStateException if this thread is active. * @exception SecurityException if the current thread cannot modify * this thread. * @see java.lang.Thread#isDaemon() * @see #checkAccess */ public final void setDaemon(boolean on) { checkAccess(); if (isAlive()) { throw new IllegalThreadStateException(); } daemon = on; } /** * Tests if this thread is a daemon thread. * * @return true if this thread is a daemon thread; * false otherwise. * @see java.lang.Thread#setDaemon(boolean) */ public final boolean isDaemon() { return daemon; } /** * Determines if the currently running thread has permission to * modify this thread. *

* If there is a security manager, its checkAccess method * is called with this thread as its argument. This may result in * throwing a SecurityException. *

* Note: This method was mistakenly non-final in JDK 1.1. * It has been made final in the Java 2 Platform. * * @exception SecurityException if the current thread is not allowed to * access this thread. * @see java.lang.SecurityManager#checkAccess(java.lang.Thread) */ public final void checkAccess() { SecurityManager security = System.getSecurityManager(); if (security != null) { security.checkAccess(this); } } /** * Returns a string representation of this thread, including the * thread's name, priority, and thread group. * * @return a string representation of this thread. */ public String toString() { ThreadGroup group = getThreadGroup(); if (group != null) { return "Thread[" + getName() + "," + getPriority() + "," + group.getName() + "]"; } else { return "Thread[" + getName() + "," + getPriority() + "," + "" + "]"; } } /** * Returns the context ClassLoader for this Thread. The context * ClassLoader is provided by the creator of the thread for use * by code running in this thread when loading classes and resources. * If not set, the default is the ClassLoader context of the parent * Thread. The context ClassLoader of the primordial thread is * typically set to the class loader used to load the application. * *

First, if there is a security manager, and the caller's class * loader is not null and the caller's class loader is not the same as or * an ancestor of the context class loader for the thread whose * context class loader is being requested, then the security manager's * checkPermission * method is called with a * RuntimePermission("getClassLoader") permission * to see if it's ok to get the context ClassLoader.. * * @return the context ClassLoader for this Thread * * @throws SecurityException * if a security manager exists and its * checkPermission method doesn't allow * getting the context ClassLoader. * @see #setContextClassLoader * @see SecurityManager#checkPermission * @see java.lang.RuntimePermission * * @since 1.2 */ public ClassLoader getContextClassLoader() { if (contextClassLoader == null) return null; SecurityManager sm = System.getSecurityManager(); if (sm != null) { ClassLoader ccl = ClassLoader.getCallerClassLoader(); if (ccl != null && ccl != contextClassLoader && !contextClassLoader.isAncestor(ccl)) { sm.checkPermission(ClassLoader.getGetClassLoaderPerm()); } } return contextClassLoader; } /** * Sets the context ClassLoader for this Thread. The context * ClassLoader can be set when a thread is created, and allows * the creator of the thread to provide the appropriate class loader * to code running in the thread when loading classes and resources. * *

First, if there is a security manager, its checkPermission * method is called with a * RuntimePermission("setContextClassLoader") permission * to see if it's ok to set the context ClassLoader.. * * @param cl the context ClassLoader for this Thread * * @exception SecurityException if the current thread cannot set the * context ClassLoader. * @see #getContextClassLoader * @see SecurityManager#checkPermission * @see java.lang.RuntimePermission * * @since 1.2 */ public void setContextClassLoader(ClassLoader cl) { SecurityManager sm = System.getSecurityManager(); if (sm != null) { sm.checkPermission(new RuntimePermission("setContextClassLoader")); } contextClassLoader = cl; } /** * Returns true if and only if the current thread holds the * monitor lock on the specified object. * *

This method is designed to allow a program to assert that * the current thread already holds a specified lock: * 

     *     assert Thread.holdsLock(obj);
     *
* * @param obj the object on which to test lock ownership * @throws NullPointerException if obj is null * @return true if the current thread holds the monitor lock on * the specified object. * @since 1.4 */ public static native boolean holdsLock(Object obj); /* Some private helper methods */ private native void setPriority0(int newPriority); private native void stop0(Object o); private native void suspend0(); private native void resume0(); private native void interrupt0(); }