java线程状态切换

java中多线程是非常重要的一块内容，在线程执行过程中会经历不同的线程状态，当然这个线程状态只是在java层面的
线程状态在java.lang.Thread.State这个枚举类中定义了
NEW：新线程还未start
RUNNABLE：正在运行中
BLOCKED：线程阻塞住
WAITING：线程在等待被唤醒
TIMED_WAITING：有时效地在等待被唤醒，过时自动唤醒
TERMINATED：线程结束
下面我们来简单看一下什么时候，线程会处于这些状态

        // NEW 
        Thread t1 = new Thread();
        Thread.sleep(100);
        System.out.println("t1 stat is : [" + t1.getState() + "]");

        // RUNNING
        Thread t2 = new Thread() {
            public void run() {
                while (true);
            }
        };
        t2.start();
        Thread.sleep(100);
        System.out.println("t2 stat is : [" + t2.getState() + "]");

        //TIMED_WAITING
        Thread t3 = new Thread() {
            public void run() {
                while (true) {
                    try {
                        Thread.sleep(10000);
                    } catch (InterruptedException e) {}
                }
            }
        };
        t3.start();
        Thread.sleep(100);
        System.out.println("t3 stat is : [" + t3.getState() + "]");

        //WAITING
        Thread t4 = new Thread() {
            public void run() {
                while (true) {
                    synchronized (this) {
                        try {
                            this.wait();
                        } catch (InterruptedException e) {}
                    }
                }
            }
        };
        t4.start();
        Thread.sleep(100);
        System.out.println("t4 stat is : [" + t4.getState() + "]");

        //BLOCKED
        final Object lock1 = new Object();
        Thread t5 = new Thread() {
            public void run() {
                synchronized (lock1) {
                    while (true);
                }
            }
        };
        Thread tv = new Thread() {
            public void run() {
                synchronized (lock1) {
                    while (true);
                }
            }
        };
        tv.start();
        t5.start();
        Thread.sleep(1000);
        System.out.println("t5 stat is : [" + t5.getState() + "]");

        //TERMINATED
        Thread t6 = new Thread() {
            public void run() {}
        };
        t6.start();
        Thread.sleep(100);
        System.out.println("t6 stat is : [" + t6.getState() + "]");

执行结果如下：

t1 stat is : [NEW]
t2 stat is : [RUNNABLE]
t3 stat is : [TIMED_WAITING]
t4 stat is : [WAITING]
t5 stat is : [BLOCKED]
t6 stat is : [TERMINATED]

new，runnable, terminate这三种状态对于我们都很容易理解
而WAITING状态会在LockSupport.park()调用的时候进入
TIMED_WAITING状态会在LockSupport.parkNanos()调用的时候进入
BLOCKED一般是在synchronized锁的时候才会进入