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java 多線程 CountDownLatch用法
CountDownLatch，一個同步輔助類，在完成一組正在其他線程中執行的操作之前，它允許一個或多個線程一直等待。
主要方法
public CountDownLatch(int count);
public void countDown();
public void await() throws
InterruptedException
構造方法參數指定了計數的次數
countDown方法，當前線程調用此方法，則計數減一
awaint方法，調用此方法會一直阻塞當前線程，直到計時器的值為0
測試例子：
package test.thread;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.CountDownLatch;
public class CountDownLatchDemo {
final static SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
public static void main(String[] args) throws InterruptedException {
CountDownLatch latch=new CountDownLatch(2);//兩個工人的協作
Worker worker1=new Worker("zhang san", 5000, latch);
Worker worker2=new Worker("li si", 8000, latch);
worker1.start();//
worker2.start();//
latch.await();//等待所有工人完成工作
System.out.println("all work done at "+sdf.format(new Date()));
}
static class Worker extends Thread{
String workerName;
int workTime;
CountDownLatch latch;
public Worker(String workerName ,int workTime ,CountDownLatch latch){
this.workerName=workerName;
this.workTime=workTime;
this.latch=latch;
}
public void run(){
System.out.println("Worker "+workerName+" do work begin at "+sdf.format(new Date()));
doWork();//工作了
System.out.println("Worker "+workerName+" do work complete at "+sdf.format(new Date()));
latch.countDown();//工人完成工作，計數器減一
}
private void doWork(){
try {
Thread.sleep(workTime);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
輸出：
Worker zhang san do work begin at 2012-03-01 10:04:58
Worker li si do work begin at 2012-03-01 10:04:58
Worker zhang san do work complete at 2012-03-01 10:05:03
Worker li si do work complete at 2012-03-01 10:05:06
all work done at 2012-03-01 10:05:06
https://www.iteye.com/topic/581476
最後更新：2017-04-02 22:16:29