线程的生命周期（6 种状态）

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线程的 6 种状态

• New：已创建，未启动，已做好准备工作
• Runnable：可运行的，调用start()方法后
• Blocked：阻塞，进入synchronized相关方法或代码块，未持有锁

• Waiting：进入等待状态（wait(), join(), park()），同样唤醒方法（notify(), notifyAll(),

  unpark(), 其中join方法要等到join执行的线程执行完毕才被唤醒）

• Timed Waiting：计时等待，需要指定时间参数，可提前被唤醒，或者等待超时后
• Terminated：终止，run方法执行完毕；出现未捕获的异常意外终止

Blocked、Waiting、TimedWaiting都成为阻塞状态

代码演示

New / Runnable / Terminated 状态

public class NewRunnableTerminated implements Runnable{
    @Override
    public void run() {
        for (int i = 0; i < 1000; i++) {
            System.out.println(i);
        }
    }

    public static void main(String[] args) {
        Thread thread = new Thread(new NewRunnableTerminated());
        // 创建线程，未启动
        System.out.println(thread.getState());
        thread.start();
        // 启动线程，可能还未运行
        System.out.println(thread.getState());
        try {
            Thread.sleep(10);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // 已运行
        System.out.println(thread.getState());

        try {
            Thread.sleep(200);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // 运行完毕
        System.out.println(thread.getState());
    }
}      

结果展示

Blocked / Waiting / TimedWaiting 状态

public class BlockedWaitingTimedWaiting implements Runnable{
    @Override
    public void run() {
        syn();
    }
    private synchronized void syn() {
        try {
            Thread.sleep(1000);
            wait();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        BlockedWaitingTimedWaiting runnable = new BlockedWaitingTimedWaiting();
        Thread thread01 = new Thread(runnable);
        thread01.start();
        Thread thread02 = new Thread(runnable);
        thread02.start();
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // 线程1正在执行 Thread.sleep(1000)，状态为 TIMED_WAITING
        System.out.println(thread01.getName() + ": " + thread01.getState());
        // 线程2未拿到锁，处于 BLOCKED 状态
        System.out.println(thread02.getName() + ": " + thread02.getState());
        try {
            Thread.sleep(1400);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // wait() 使得进入 WAITING 状态
        System.out.println(thread01.getName() + ": " + thread01.getState());
    }
}