代码参考https://www.cnblogs.com/nullzx/p/5272807.html
package Thread;
import java.util.*;
import java.util.concurrent.*;
//控制一个线程等待多个线程
public class CountDownLatchDemo {
// a、b、c、d同时交给线程池,c、d会在a、b结束后开始执行;
// 重点是countDown和await方法
private CountDownLatch latch = new CountDownLatch(2);
private Random rmd = new Random();
class FirstTask implements Runnable {
private String id;
public FirstTask(String id) {
this.id = id;
}
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println("Thread " + id + " is start");
try {
Thread.sleep(rmd.nextInt(1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("Thread " + id + " is over");
// 执行countdown会减1
latch.countDown();
}
}
class SecondTask implements Runnable {
private String id;
public SecondTask(String id) {
this.id = id;
}
@Override
public void run() {
// TODO Auto-generated method stub
try {
// 等待,count=0时立刻执行
latch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("----------Thread " + id + " is start");
try {
Thread.sleep(rmd.nextInt(1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("----------Thread " + id + " is over");
}
}
public static void main(String[] args) {
ExecutorService es = Executors.newCachedThreadPool();
CountDownLatchDemo latchDemo = new CountDownLatchDemo();
es.submit(latchDemo.new SecondTask("c"));
es.submit(latchDemo.new SecondTask("d"));
es.submit(latchDemo.new FirstTask("a"));
es.submit(latchDemo.new FirstTask("b"));
es.shutdown();
}
}
https://blog.csdn.net/u011345136/article/details/46842183
package Thread;
import java.util.*;
import java.util.concurrent.*;
//一个主任务等待两个子任务,通过CyclicBarrier的await()实现,
//此Runnable任务在CyclicBarrier的数目达到后,所有其它线程被唤醒前被执行。
public class CyclicBarrierDemo {
class MainTask implements Runnable {
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println("-----主任务开始执行-----");
}
}
class SubTask implements Runnable {
private String name;
private CyclicBarrier cyclicBarrier;
public SubTask(String name, CyclicBarrier cyclicBarrier) {
// TODO Auto-generated constructor stub
this.name = name;
this.cyclicBarrier = cyclicBarrier;
}
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println("[子任务" + name + "]开始执行了!");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("[子任务" + name + "]执行完成了,并通知障碍器已经完成了");
try {
// 执行await方法+1
cyclicBarrier.await();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (BrokenBarrierException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
CyclicBarrierDemo cDemo = new CyclicBarrierDemo();
CyclicBarrier cyclicBarrier = new CyclicBarrier(2, cDemo.new MainTask());
//CyclicBarrier cyclicBarrier = new CyclicBarrier(2, null);
SubTask A = cDemo.new SubTask("A", cyclicBarrier);
SubTask B = cDemo.new SubTask("B", cyclicBarrier);
ExecutorService executor = Executors.newCachedThreadPool();
executor.execute(A);
executor.execute(B);
executor.shutdown();
}
}