【八股】Java 线程状态转化

news2024/9/22 17:20:45

线程一共有六种状态

1. NEW - 新建

public static void main(String[] args) throws ExecutionException, InterruptedException {
    Thread t = new Thread(() -> {
        System.out.println("running");
    }, "t1");
    System.out.println(t.getState()); // 线程创建
}

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2. RUNNABLE - 可执行

public static void main(String[] args) throws ExecutionException, InterruptedException {
    Thread t = new Thread(() -> {
        System.out.println("running");
    }, "t1");
    System.out.println(t.getState()); // 线程创建
    
    t.start();
    System.out.println(t.getState()); // 执行start()
}

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3. BLOCKED- 阻塞

public static void main(String[] args) throws ExecutionException, InterruptedException {
    Object LOCK = new Object();
    Thread t = new Thread(() -> {
        System.out.println("before sync");
        synchronized (LOCK) {
            System.out.println("in sync");
        }
    }, "t1");
    System.out.println(t.getState()); // 线程创建

    t.start();
    synchronized (LOCK) {
        System.out.println("running");
        Thread.sleep(3000);
    }
    System.out.println(t.getState()); // 执行start()
}

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4. WAITING - 等待

public static void main(String[] args) throws ExecutionException, InterruptedException {
    ObjectLOCK = new Object();
    Thread t = new Thread(() -> {
        synchronized (LOCK) {
            try {
                LOCK.wait();
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }

        }
    }, "t1");
    System.out.println(t.getState()); // 输出：NEW 线程创建

    t.start();
    Thread.sleep(1000);
    System.out.println(t.getState());

}

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5. TIMED_WAITING - 计时等待

public static void main(String[] args) throws ExecutionException, InterruptedException {
    Object LOCK = new Object();
    Thread t = new Thread(() -> {
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }, "t1");
    System.out.println(t.getState()); // 输出：NEW 线程创建

    t.start();
    Thread.sleep(1000);
    System.out.println(t.getState());

}

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6. TERMINATED - 死亡

public static void main(String[] args) throws ExecutionException, InterruptedException {
    Object LOCK = new Object();
    Thread t = new Thread(() -> {}, "t");
    System.out.println(t.getState()); // 输出：NEW 线程创建

    t.start();
    Thread.sleep(1000); // 让线程t执行完
    System.out.println(t.getState());
}