Java countDownLatch 线程辅助类
x286
9年前
countDownLatch 线程辅助类,是一个线程计数类,用来线程同步,每当一个线程执行完成后,就是加1,当达到计数,就算执行完成。初始值必须小于等于要执行的线程数,为0 是,不其作用,大于0,小于等于线程数时,为同步线程数,当大于线程数时,为死循环(可能不对)反正就是一直等待。
import java.text.SimpleDateFormat; import java.util.Date; import java.util.concurrent.CountDownLatch; public class T1 { final static SimpleDateFormat sdf = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss"); public static void main(String[] args) throws Exception { CountDownLatch countDownLatch = new CountDownLatch(3); Worker w1 = new Worker("w1", 2000, countDownLatch); Worker w2 = new Worker("w2", 5000, countDownLatch); w1.start();// w2.start();// countDownLatch.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; } @Override public void run() { System.out.println("Worker " + workerName + " do work begin at " + sdf.format(new Date())); try { Thread.sleep(workTime); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("Worker " + workerName + " do work complete at " + sdf.format(new Date())); latch.countDown();// 工人完成工作,计数器减一 } } }