2019独角兽企业重金招聘Python工程师标准>>> 
http://bughope.iteye.com/blog/2081935
在上一篇文章中写道用一个静态的变量保存线程的执行状态,并用时间等待的方法后来仔细考虑,其实是
线程不安全的.多个线程同时执行这个类时,这个静态变量的值就不能保证了.
用一个线程同步的Map保存这个值,勉强能实现[每个线程生产一个不重复的map的key]
但是这样很麻烦.
java. util. concurrent.CountDownLatch
却能完美的实现.能线程安全的计数,因为每个实现的主线程在并发的情况下java.util.concurrent.CountDownLatch; 是新的实例 不会像上一篇一样需要处理计数器的线程安全.
具体代码如下
package org.masque.effective;import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
/*** * @author masque.java@gmail.com**/
public class ThreadTest {public static void main(String[] args) throws InterruptedException {CountDownLatch latch=new CountDownLatch(3);//数量标示线程的个数(new Thread1(latch)).start();(new Thread2(latch)).start();(new Thread3(latch)).start();latch.await();//等待线程执行完成.还有一个重载的方法可以设置超时时间System.out.println("over!");}
}class Thread1 extends Thread{CountDownLatch latch;public Thread1(CountDownLatch latch){this.latch = latch;}@Overridepublic void run() {for (int i=10;i<20;i++) {System.out.println("Thread1===========:"+i);try {TimeUnit.SECONDS.sleep(1);} catch (InterruptedException e) {e.printStackTrace();}}latch.countDown();//完成后计数}
}class Thread2 extends Thread{CountDownLatch latch;public Thread2(CountDownLatch latch){this.latch = latch;}@Overridepublic void run() {for (int i=10;i<20;i++) {System.out.println("Thread2===========:"+i);try {TimeUnit.SECONDS.sleep(1);} catch (InterruptedException e) {e.printStackTrace();}}latch.countDown();//完成后计数}
}class Thread3 extends Thread{CountDownLatch latch;public Thread3(CountDownLatch latch){this.latch = latch;}@Overridepublic void run() {for (int i=10;i<20;i++) {System.out.println("Thread3===========:"+i);try {TimeUnit.SECONDS.sleep(1);} catch (InterruptedException e) {e.printStackTrace();}}latch.countDown();//完成后计数}
}
)
)