4、join与中断线程

哪个线程对象调用这个join方法，表示哪个线程进入执行的状态，等待这个线程把它的任务执行完。

让调用的线程先执行指定时间或执行完毕后再执行其他的线程

应用场景：当主线程执行到一半，需要线程0返回的数据才能继续执行时。

package com.chocus.demo1;public class ThreadDemo02 {  public static void main(String[] args) {    MyRunnables mr = new MyRunnables();    Thread t = new Thread(mr);    t.start();    for (int i = 0; i < 10; i++) {      System.out.println(Thread.currentThread().getName() + "--" + i);      try {        Thread.sleep(300);      } catch (InterruptedException e) {        // TODO Auto-generated catch block        e.printStackTrace();      }      if(i == 5){        try {          t.join();        } catch (InterruptedException e) {          // TODO Auto-generated catch block          e.printStackTrace();        }      }    }  }}class MyRunnables implements Runnable {  @Override  public void run() {    // TODO Auto-generated method stub    for (int i = 0; i < 10; i++) {      System.out.println(Thread.currentThread().getName() + "--" + i);      try {        Thread.sleep(300);      } catch (InterruptedException e) {        // TODO Auto-generated catch block        e.printStackTrace();      }    }  }}

结果:

main--0Thread-0--0main--1Thread-0--1main--2Thread-0--2main--3Thread-0--3main--4Thread-0--4main--5Thread-0--5Thread-0--6Thread-0--7Thread-0--8Thread-0--9main--6main--7main--8main--9

中断分为正常中断和异常中断

interrupt中断线程并不能真正使线程中断，而是做了一个中断的标记

interrupted方法会清除线程的中断标记，调用一次后就会清除

sleep方法因为线程中断而抛出异常的同时会清除线程的中断标记

package com.chocus.demo1;public class ThreadDemo03 {  public static void main(String[] args) {    MyRunnable03 mr = new MyRunnable03();    Thread t = new Thread(mr);    t.start();    for (int i = 0; i < 50; i++) {      System.out.println(Thread.currentThread().getName() + "--" + i);      try {        Thread.sleep(300);      } catch (InterruptedException e) {        // TODO Auto-generated catch block        e.printStackTrace();      }      if (i == 10) {        t.interrupt();      }    }  }}class MyRunnable03 implements Runnable {  @Override  public void run() {    for (int i = 0; i < 50; i++) {      System.out.println(Thread.currentThread().getName() + "当前中断状态为：" + Thread.interrupted());      boolean flag = Thread.interrupted();      System.out.println(flag);      if (flag) {        break;      }      System.out.println(Thread.currentThread().getName() + "--" + i);      try {        Thread.sleep(300);      } catch (InterruptedException e) {        // TODO Auto-generated catch block        e.printStackTrace();        Thread.currentThread().interrupt();      }    }  }}

结果

main--0Thread-0当前中断状态为：falsefalseThread-0--0main--1Thread-0当前中断状态为：falsefalseThread-0--1Thread-0当前中断状态为：falsemain--2falseThread-0--2Thread-0当前中断状态为：falsefalseThread-0--3main--3Thread-0当前中断状态为：falsefalseThread-0--4main--4Thread-0当前中断状态为：falsemain--5falseThread-0--5main--6Thread-0当前中断状态为：falsefalseThread-0--6Thread-0当前中断状态为：falsefalseThread-0--7main--7main--8Thread-0当前中断状态为：falsefalseThread-0--8main--9Thread-0当前中断状态为：falsefalseThread-0--9main--10Thread-0当前中断状态为：falsefalseThread-0--10Thread-0当前中断状态为：falsemain--11truemain--12main--13main--14main--15main--16main--17main--18main--19

上面的方式会受到线程执行速度及执行权的影响，并不一定会百分百成功中断。下面才用推荐的自定义的中断标记

package com.chocus.demo1;public class ThreadDemo04 {  public static void main(String[] args) {    MyRunnable04 mr = new MyRunnable04();    Thread t = new Thread(mr);    t.start();    for (int i = 0; i < 20; i++) {      System.out.println(Thread.currentThread().getName() + "==" + i);      try {        Thread.sleep(300);      } catch (InterruptedException e) {        // TODO Auto-generated catch block        e.printStackTrace();      }      if (i == 10) {        mr.flag = false;      }    }  }}class MyRunnable04 implements Runnable {  public boolean flag = true;  public MyRunnable04() {    flag = true;  }  @Override  public void run() {    for (int i = 0; i < 20; i++) {      if (flag) {        System.out.println(Thread.currentThread().getName() + "--" + i);      } else {        break;      }      try {        Thread.sleep(300);      } catch (InterruptedException e) {        // TODO Auto-generated catch block        e.printStackTrace();      }    }  }}

结果

main==0Thread-0--0main==1Thread-0--1Thread-0--2main==2Thread-0--3main==3main==4Thread-0--4main==5Thread-0--5main==6Thread-0--6main==7Thread-0--7main==8Thread-0--8main==9Thread-0--9main==10Thread-0--10main==11main==12main==13main==14main==15main==16main==17main==18main==19