CountDownLatch的使用

代码

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;

//# $ 号打印50时,三个线程交替执行
public class TestCountDownLatch {

	public static void main(String[] args) {
		CountDownLatch cdl = new CountDownLatch(2);
		CyclicBarrier cb = new CyclicBarrier(3); 
		
		Thread t1 = new Thread(){
			public void run(){
				for(int i = 1 ; i <= 100 ; i++){
					System.out.println("### "+i);
					if (i == 50) cdl.countDown();
					try {
						Thread.sleep(100);
						if (i == 99) cb.await();
						
					} catch (Exception e) {
						e.printStackTrace();
					}
				}
			}
		};
		Thread t2 = new Thread(){
			public void run(){
				for(int i = 1 ; i <= 100 ; i++){
					System.out.println("$$$ "+i);
					if (i == 50) cdl.countDown(); //countDownLatch为0的时候,释放下面打印*号的线程 三个线程交替执行
					try {
						Thread.sleep(100);
						if (i==99) cb.await();
					} catch (Exception e) {
						e.printStackTrace();
					}
				}			
			}
		};
		Thread t3 = new Thread(){
			public void run(){
				try {
					cdl.await();	//先对打印*号的线程进行阻塞   阻塞线程
				} catch (InterruptedException e1) {
					e1.printStackTrace();
				}
				for(int i = 1 ; i <= 100 ; i++){
					System.out.println("*** "+i);
					try {
						Thread.sleep(100);
						if (i==99) cb.await();
					} catch (Exception e) {
						e.printStackTrace();
					}
				}				
			}
		};
		t1.start();
		t2.start();
		t3.start();
	}
}

运行结果

这辈子坚持与不坚持都不可怕，怕的是独自走在坚持的道路上！！！