多线程入门（3）：线程的生命周期

//java.lang.Thread.State
public enum State {
    NEW,
    RUNNABLE,
    BLOCKED,
    WAITING,
    TIMED_WAITING,
    TERMINATED;
}

1 状态间的转化图示

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展示线程的NEW、RUNNABLE、Terminated状态。即使是正在运行，也是Runnable状态，而不是Running。

/**
 * 展示线程的NEW、RUNNABLE、Terminated状态。即使是正在运行，也是Runnable状态，而不是Running。
 */
public class NewRunnableTerminated {
    public static void main(String[] args) {
        Thread thread = new Thread(() -> {
            for (int i = 0; i < 1000; i++) {
                System.out.println(i);
            }
        });
        //打印出NEW的状态
        System.out.println(thread.getState());
        thread.start();
        System.out.println(thread.getState());
        try {
            Thread.sleep(10);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //打印出RUNNABLE的状态，即使是正在运行，也是RUNNABLE，而不是RUNNING
        System.out.println(thread.getState());
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //打印出TERMINATED状态
        System.out.println(thread.getState());
    }
}

展示Blocked, Waiting, TimedWaiting

public class BlockedWaitingTimedWaiting implements Runnable{
    public static void main(String[] args) {
        BlockedWaitingTimedWaiting runnable = new BlockedWaitingTimedWaiting();
        Thread thread1 = new Thread(runnable);
        thread1.start();
        Thread thread2 = new Thread(runnable);
        thread2.start();
        try {
            Thread.sleep(5);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //打印出Timed_Waiting状态，因为正在执行Thread.sleep(1000);
        System.out.println(thread1.getState());
        //打印出BLOCKED状态，因为thread2想拿得到sync()的锁却拿不到
        System.out.println(thread2.getState());
        try {
            Thread.sleep(1300);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //打印出WAITING状态，因为执行了wait()
        System.out.println(thread1.getState());
    }
    @Override
    public void run() {
        syn();
    }
    /**
     * 线程1进入方法后sleep(1000)
     * 线程2陷入阻塞状态(Blocked)
     */
    private synchronized void syn() {
        try {
            Thread.sleep(1000);
            wait();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}