Java.util.Concurrent.CountDownLatch

package com.bjsxt.height.concurrent019;

import java.util.concurrent.CountDownLatch;

/**
 * The CountDownLatch class is located in the java.util.concurrent package, and it can be used to implement counter-like functions.
 * For example, there is a task A,
 * It can only be executed after the other 4 tasks are executed. At this time, CountDownLatch can be used to achieve this function
 *
 */
public class UseCountDownLatch {

	public static void main(String[] args) {
		
		final CountDownLatch countDown = new CountDownLatch(2);//The parameter indicates several countDown();
		
		Thread t1 = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					System.out.println("Enter thread t1" + "Waiting for other threads to finish processing...");
					countDown.await();//Block here, wait for other threads to finish executing before they can go down
					System.out.println("t1 thread continues to execute...");
				} catch (InterruptedException e) {
					e.printStackTrace ();
				}
			}
		},"t1");
		
		Thread t2 = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					System.out.println("t2 thread initializes...");
					Thread.sleep(3000);
					System.out.println("The t2 thread is initialized, notify the t1 thread to continue...");
					countDown.countDown();//After execution, notify
				} catch (InterruptedException e) {
					e.printStackTrace ();
				}
			}
		});
		Thread t3 = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					System.out.println("t3 thread initializes...");
					Thread.sleep(4000);
					System.out.println("The t3 thread is initialized, notify the t1 thread to continue...");
					countDown.countDown();//After execution, notify
				} catch (InterruptedException e) {
					e.printStackTrace ();
				}
			}
		});
		
		t1.start();
		t2.start();
		t3.start();
		
		
		
	}
}