漫话JAVA线程状态

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很多次面试都遇到了一个问题: 线程有那几个状态?

OK, 线程到底有哪几个状态?

看代码可知: 5个状态, NEW, RUNNABLE, RUNNING, TERMINATE, BLOCKED, WAITING, TIMED_WAITING

public enum State {
        /**
         * Thread state for a thread which has not yet started.
         */
        NEW,

        /**
         * Thread state for a runnable thread.  A thread in the runnable
         * state is executing in the Java virtual machine but it may
         * be waiting for other resources from the operating system
         * such as processor.
         */
        RUNNABLE,

        /**
         * Thread state for a thread blocked waiting for a monitor lock.
         * A thread in the blocked state is waiting for a monitor lock
         * to enter a synchronized block/method or
         * reenter a synchronized block/method after calling
         * {@link Object#wait() Object.wait}.
         */
        BLOCKED,

        /**
         * Thread state for a waiting thread.
         * A thread is in the waiting state due to calling one of the
         * following methods:
         * 

         *   
{@link Object#wait() Object.wait} with no timeout
         *   
{@link #join() Thread.join} with no timeout
         *   
{@link LockSupport#park() LockSupport.park}
         * 
         *
         * 
A thread in the waiting state is waiting for another thread to
         * perform a particular action.
         *
         * For example, a thread that has called Object.wait()
         * on an object is waiting for another thread to call
         * Object.notify() or Object.notifyAll() on
         * that object. A thread that has called Thread.join()
         * is waiting for a specified thread to terminate.
         */
        WAITING,

        /**
         * Thread state for a waiting thread with a specified waiting time.
         * A thread is in the timed waiting state due to calling one of
         * the following methods with a specified positive waiting time:
         * 

         *   
{@link #sleep Thread.sleep}
         *   
{@link Object#wait(long) Object.wait} with timeout
         *   
{@link #join(long) Thread.join} with timeout
         *   
{@link LockSupport#parkNanos LockSupport.parkNanos}
         *   
{@link LockSupport#parkUntil LockSupport.parkUntil}
         * 
         */
        TIMED_WAITING,

        /**
         * Thread state for a terminated thread.
         * The thread has completed execution.
         */
        TERMINATED;
    }

 

状态实例见代码

public class TestJava {

    private final static Object lock = new Object();

    public static void main(String[] args) throws InterruptedException {
        Thread t = new Thread(){
            public void run(){
                System.out.println("RUNNING: " + this.getState());
                synchronized(lock){
                    try {
                        Thread.sleep(3000);
                        lock.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        System.out.println("NOT START:" + t.getState());
        t.start();

        while (true){
            Thread.sleep(2000);
            System.out.println("WAITING:" + t.getState());
            synchronized (lock){
                System.out.println("MONITOR LOCK:" + t.getState());
                lock.notify();
                System.out.println("AFTER NOTIFY: " + t.getState());
            }
            Thread.sleep(10000);
        }
    }
}

 

状态转换图:

 

 

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