线程停止、休眠、礼让、强制执行、观测线程状态

一、线程停止：

1.不推荐使用jdk提供的stop()、destroy()方法。【已废弃】

2.推荐线程自己停下，建议使用一个标识位进行终止变量，当flag=false，则终止线程运行

//测试stop
//1.建议线程正常停止--》利用次数，不建议死循环
//2.建议使用一个标识符public class TestStop implements Runnable{private boolean flag = true;@Overridepublic void run() {int i = 0;while (flag){System.out.println("run----->" + i++);}}public void stop(){this.flag = false;}public static void main(String[] args) {TestStop testStop = new TestStop();new Thread(testStop).start();for (int i = 0; i < 1000; i++) {System.out.println("main---->" + i);if (i==900){testStop.stop();System.out.println("线程停止了");}}}
}

二、线程休眠：

1.sleep (时间)指定当前线程阻塞的毫秒数;

2. sleep存在异常InterruptedException;

3.sleep时间达到后线程进入就绪状态;

4.sleep可以模拟网络延时，倒计时等。

5.每一个对象都有一个锁，sleep不会释放锁;

public class TestSleep1 {public static void main(String[] args) {try {tenDown();} catch (InterruptedException e) {throw new RuntimeException(e);}}//模拟倒计时public static void tenDown() throws InterruptedException {int num = 10;while (true){Thread.sleep(1000);System.out.println(num--);if (num == 0){break;}}}}

public static void main(String[] args) {//打印当前系统时间Date date = new Date(System.currentTimeMillis());//获取系统当前时间while (true){try {Thread.sleep(1000);System.out.println(new SimpleDateFormat("HH:mm:ss").format(date));date = new Date(System.currentTimeMillis());//更新系统时间} catch (InterruptedException e) {throw new RuntimeException(e);}}}

三、线程礼让：

1.礼让线程，让当前正在执行的线程暂停，但不阻塞

2.将线程从运行状态转为就绪状态

3.让cpu重新调度，礼让不一定成功!看CPU心情

public class TestYield {public static void main(String[] args) {MyYield myYield = new MyYield();new Thread(myYield,"a").start();new Thread(myYield,"b").start();}
}class MyYield implements Runnable{@Overridepublic void run() {System.out.println(Thread.currentThread().getName()+ "线程开始");Thread.yield();//礼让System.out.println(Thread.currentThread().getName()+ "线程结束");}
}

四、线程强制执行：

Join合并线程，待此线程执行完成后，再执行其他线程，其他线程阻塞

public class TestJoin implements Runnable{@Overridepublic void run() {for (int i = 1; i <= 100 ; i++) {System.out.println("线程VIP来了" + i);}}public static void main(String[] args) {TestJoin testJoin = new TestJoin();Thread thread = new Thread(testJoin);thread.start();for (int i = 1; i < 1000; i++) {if (i ==100){try {thread.join();//插队} catch (InterruptedException e) {throw new RuntimeException(e);}}System.out.println("main" + i);}}
}

五、观测线程状态：

public class TestState {public static void main(String[] args) throws InterruptedException {Thread thread = new Thread(()->{for (int i = 0; i < 5; i++) {try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}}System.out.println("////////");});//观察状态Thread.State state = thread.getState();System.out.println(state);//NEW//观察启动后thread.start();//启动线程state = thread.getState();System.out.println(state);//Runwhile (state != Thread.State.TERMINATED){//只要线程不终止，就一直输出状态Thread.sleep(100);state = thread.getState();//更新线程状态System.out.println(state);}}
}