Java 多线程控制 CountDownLatch

多线程开发过程中，可能会有一些需求如这样：需要在一定数量线程启动后，做一些其他的操作。那么利用CountDownLatch再方便不过了。不多说上代码：

package thread;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class CountDownLatchTest implements Runnable
{

	private int i;

	private CountDownLatch countDownLatch;

	public CountDownLatchTest(CountDownLatch count, int i)
	{
		this.countDownLatch = count;
		this.i = i;
	}

	public void run()
	{
		int count = 5;
		while (count > 0)
		{
			try
			{
				Thread.sleep(1000);
			} catch (InterruptedException e)
			{
				e.printStackTrace();
			}
			count--;
		}
		this.countDownLatch.countDown();
		System.out.println("I am " + this.i);
	}

	public static void main(String[] args) throws InterruptedException
	{
		CountDownLatch countDownLatch = new CountDownLatch(10);
		ExecutorService threadpool = Executors.newCachedThreadPool();
		for (int i = 0; i < 20; i++)
		{
			CountDownLatchTest test = new CountDownLatchTest(countDownLatch, i);
			threadpool.submit(test);
		}
		countDownLatch.await();
		System.out.println("Now, Let's go! Do others!!!");

		threadpool.shutdown();
	}

}