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public  class  java.lang.Thread
    extends  java.lang.Object  (I-§1.12)
    implements java.lang.Runnable  (I-§1.23)
{
        // Fields
    public final static int MAX_PRIORITY;	§1.19.1
    public final static int MIN_PRIORITY;	§1.19.2
    public final static int NORM_PRIORITY;	§1.19.3

        // Constructors
    public Thread();	§1.19.4
    public Thread(Runnable  target);	§1.19.5
    public Thread(Runnable  target, String  name);	§1.19.6
    public Thread(String  name);	§1.19.7
    public Thread(ThreadGroup  group, Runnable  target);	§1.19.8
    public Thread(ThreadGroup  group,	§1.19.9
                      Runnable  target, String  name);
    public Thread(ThreadGroup  group, String  name);	§1.19.10

        // Methods

    public static int activeCount();	§1.19.11
    public void checkAccess();	§1.19.12
    public int countStackFrames();	§1.19.13
    public static Thread currentThread();	§1.19.14
    public void destroy();	§1.19.15
    public static void dumpStack();	§1.19.16
    public static int enumerate(Thread  tarray[]);	§1.19.17
    public final String getName();	§1.19.18
    public final int getPriority();	§1.19.19
    public final ThreadGroup getThreadGroup();	§1.19.20
    public void interrupt();	§1.19.21
    public static boolean interrupted();	§1.19.22
    public final boolean isAlive();	§1.19.23
    public final boolean isDaemon();	§1.19.24
    public boolean isInterrupted();	§1.19.25
    public final void join();	§1.19.26
    public final void  join(long  millis);	§1.19.27
    public final void join(long  millis, int  nanos)	§1.19.28
    public final void resume();	§1.19.29
    public void run();	§1.19.30
    public final void setDaemon(boolean  on);	§1.19.31
    public final void setName(String  name);	§1.19.32
    public final void setPriority(int  newPriority);	§1.19.33
    public static void sleep(long  millis);	§1.19.34
    public static void sleep(long  millis, int  nanos)	§1.19.35
    public void start();	§1.19.36
    public final void stop();	§1.19.37
    public final void  stop(Throwable  obj);	§1.19.38
    public final void suspend();	§1.19.39
    public String toString();	§1.19.40
    public static void yield();	§1.19.41
}

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 dæmon. 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 dæmon thread if and only if the creating thread is a dæmon.

When a Java Virtual Machine starts up, there is usually a single non-dæmon 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:

• The exit method (I-§1.14.5) of class Runtime has been called and the security manager has permitted the exit operation to take place.
• All threads that are not dæmon threads have died, either by returning from the call to the run method (I-§1.19.30) or by performing the stop method (I-§1.19.37).

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 whose job is to compute 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
                		...
        	}
}

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

class PrimeRun implements Runnable {
	        long minPrime;
        	PrimeRun(long minPrime) {
                		this.minPrime = minPrime;
        	}

        	public void run() {
             		// compute primes larger than minPrime
              		...
        	}
}

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

The maximum priority that a thread can have.

The minimum priority that a thread can have.

The default priority that is assigned to a thread.

Allocates a new Thread object. This constructor has the same effect as Thread(null, null, gname) (I-§1.19.9) where gname is a newly generated name. Automatically generated names are of the form "Thread-"+n where n is an integer.

Allocates a new Thread object. This constructor has the same effect as Thread(null, target, gname) (I-§1.19.9) where gname is a newly generated name. Automatically generated names are of the form "Thread-"+n where n is an integer.

Parameters:

target - the object whose run method is called

Allocates a new Thread object. This constructor has the same effect as Thread(null, target, name) (I-§1.19.9).

Parameters:

target - the object whose run method is called

name - the name of the new thread

Allocates a new Thread object. This constructor has the same effect as Thread(null, null, name) (I-§1.19.9).

Parameters:

name - the name of the new thread

Allocates a new Thread object. This constructor has the same effect as Thread(group, target, gname) (I-§1.19.9) where gname is a newly generated name. Automatically generated names are of the form "Thread-"+n where n is an integer.

Parameters:

group - the thread group

target - the object whose run method is called

Throws

SecurityException (I-§1.43)

If the current thread cannot create a thread in the specified thread group.

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 not null, the checkAccess method (I-§1.20.5) of that thread group is called with no arguments; this may result in throwing a SecurityException; if group is null, the new process belongs to the same group as the thread this is created the new thread.

If the target argument is not null, the run method of the target (I-§1.23.1) is called when this thread is started. If the target argument is null, this thread's run method (I-§1.19.30) 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 set-Priority (I-§1.19.33) may be used to change the priority to a new value.

The newly created thread is a initially marked as being a dæmon thread if and only if the thread creating it is currently marked as a dæmon thread. The method setDaemon (I-§1.19.31) may be used to change whether or not a thread is a dæmon.

Parameters:

group - the thread group

target - the object whose run method is called

name - the name of the new thread

Throws

SecurityException (I-§1.43)

If the current thread cannot create a thread in the specified thread group

Allocates a new Thread object. This constructor has the same effect as Thread(group, null, name) (I-§1.19.9)

Parameters:

group - the thread group

name - the name of the new thread

Throws

SecurityException (I-§1.43)

If the current thread cannot create a thread in the specified thread group.

Returns:

the current number of threads in this thread's thread group.

Determines if the currently running thread has permission to modify this thread.

If there is a security manager, its checkAccess method (I-§1.15.4) is called with this thread as its argument. This may result in throwing a SecurityException.

Throws

SecurityException (I-§1.43)

If the current thread is not allowed to access this thread.

Counts the number of stack frames in this thread. The thread must be suspended.

Returns:

the number of stack frames in this thread.

Throws

IllegalThreadStateException (I-§1.34)

If this thread is not suspended.

Find the currently executing thread.

Returns:

the currently executing thread.

destroy¹

Destroys this thread, without any cleanup. Any monitors it has locked remain locked.

Prints a stack trace of the current thread. Used only for debugging.

See Also:

printStackTrace in class Throwable (I-§1.21.5).

Copies into the array argument every thread in this thread's thread group. This method simple calls the enumerate method (I-§1.20.7) of this thread's thread group with the array argument.

Returns:

the number of threads put into the array.

Returns:

this thread's name.

Returns:

this thread's current priority.

Returns:

this thread's thread group.

Interrupts this thread.

Returns:

true if the current thread has been interrupted; false otherwise.

Determines if this thread is alive A thread is alive if it has been started and has not yet died.

Returns:

true if this thread is alive; false otherwise.

Returns:

true if this thread is a dæmon thread; false otherwise.

Returns:

true if this thread has been interrupted; false otherwise.

Waits for this thread to die.

Throws

InterruptedException (I-§1.37)

Another thread has interrupted the current thread.

Waits at most millis milliseconds for for this thread to die. A timeout of 0 means to wait forever.

Parameters:

millis - the time to wait in milliseconds

Throws

InterruptedException (I-§1.37)

Another thread has interrupted the current thread.

Waits at most millis milliseconds plus nanos nanoseconds for this thread to die.

Parameters:

millis - the time to wait in milliseconds

nanos - 0-999999 additional nanoseconds to wait

Throws

InterruptedException (I-§1.37)

Another thread has interrupted the current thread.

Resumes a suspended thread.

First, the checkAccess method (I-§1.19.12) of this thread is called with no arguments. This may result in throwing a SecurityException (in the current thread).

If the thread is alive (I-§1.19.23) but suspended, it is resumed and is permitted to make progress in its execution.

Throws

SecurityException (I-§1.43)

If the current thread cannot modify this thread.

If this thread was constructed using a separate Runnable run object (see I-§1.19.9 on page 141 for more information), then that Runnable object's run method (I-§1.23.1) is called. Otherwise, this method does nothing and returns.

Subclasses of Thread should override this method.

See Also:

start (I-§1.19.36)
stop (I-§1.19.37).

Marks this thread as either a dæmon thread or a user thread. The Java Virtual Machine exits when the only threads running are all dæmon threads.

This method must be called before the thread is started.

Parameters:

on - if true, marks this thread as a dæmon thread

Throws

IllegalThreadStateException (I-§1.34)

If this thread is active.

Changes the name of this thread to be equal to the argument name.

First the checkAccess method (I-§1.19.12) of this thread is called with no arguments. This may result in throwing a SecurityException.

Parameters:

name - the new name for this thread.

Throws

SecurityException (I-§1.43)

If the current thread cannot modify this thread.

Changes the priority of this thread

First the checkAccess method (I-§1.19.12) 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 (I-§1.20.11) of the thread's thread group (I-§1.19.20).

Throws

IllegalArgumentException (I-§1.32)

If the priority is not in the range MIN_PRIORITY to MAX_PRIORITY.

Throws

SecurityException (I-§1.43)

If the current thread cannot modify this thread.

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 (see I-§1.12.7 on page 72 for further discussion of monitors).

Parameters:

millis - the length of time to sleep in milliseconds

Throws

InterruptedException (I-§1.37)

Another thread has interrupted this thread.

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 (see I-§1.12.7 on page 72 for further discussion of monitors).

Parameters:

millis - the length of time to sleep in milliseconds

nanos - 0-999999 additional nanoseconds to sleep

Throws

InterruptedException (I-§1.37)

Another thread has interrupted this thread.

Causes this thread to begin execution; the Java Virtual Machine calls the run method (I-§1.19.30) 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).

Throws

IllegalThreadStateException (I-§1.34)

If the thread was already started.

See Also:

run (I-§1.19.30)
stop (I-§1.19.37).

Forces this thread to stop executing.

First, the checkAccess method (I-§1.19.12) of this thread is called with no arguments. This may result in throwing a SecurityException (in the current thread).

The thread represented by the this thread is forced to stop whatever it is doing abnormally and to throw a newly created ThreadDeath (I-§1.59) 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 will cause finally clauses of try statements to be executed before the thread officially dies). If a catch clause does catch 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 (I-§1.20.23) does not print out a message or otherwise notify the application if the uncaught exception is an instance of ThreadDeath.

See Also:

start (I-§1.19.36)
run (I-§1.19.30).

Throws

SecurityException (I-§1.43)

If the current thread cannot modify this thread.

Forces the this thread to stop executing.

First, the checkAccess method (I-§1.19.12) of this thread is called with no arguments. 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 (I-§1.19.37) 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.

Parameters:

obj - the Throwable object to be thrown

Throws

SecurityException (I-§1.43)

If the current thread cannot modify this thread.

Suspends this thread.

First, the checkAccess method (I-§1.19.12) of this thread is called with no arguments. This may result in throwing a SecurityException (in the current thread).

If the thread is alive (I-§1.19.23), it is suspended and makes no further progress unless and until it is resumed.

Throws

SecurityException (I-§1.43)

If the current thread cannot modify this thread.

Returns:

a string representation of this thread.

Overrides:

toString in class Object (I-§1.12.9).

Causes the currently executing thread object to temporarily pause and allow other threads to execute.

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