public class CyclicBarrierextends Object

事例：

package org.wangyi.tool;

import java.util.Base64;
import java.util.Random;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
* 线程障碍器
*
* @author wangyi
* @version 1.0 <br />
* <a href="http://www.mamicode.com/www.baidu.com">百度一下</a>
*/
public class CyclicBarrierTest {
public static void main(String[] args) {
ExecutorService threadpool = Executors.newCachedThreadPool();
final CyclicBarrier cb = new CyclicBarrier(3);
for (int i = 0; i < 3; i++) {
Runnable runnable = new Runnable() {
@Override
public void run() {
try {

Thread.sleep((long) (Math.random() * 10000));
System.out.println("线程"
+ Thread.currentThread().getName()
+ "即将到达饭点1看，当前已有 "
+ (cb.getNumberWaiting() + 1)
+ "个已经到达,"
+ (cb.getNumberWaiting() == 2 ? "人来起了，开饭了！"
: "等候其他人..."));
cb.await();
Thread.sleep((long) (Math.random() * 10000));
System.out.println("线程"
+ Thread.currentThread().getName()
+ "即将到达饭点2看，当前已有 "
+ (cb.getNumberWaiting() + 1)
+ "个已经到达,"
+ (cb.getNumberWaiting() == 2 ? "人来起了，开饭了！"
: "等候其他人..."));
cb.await();
Thread.sleep((long) (Math.random() * 10000));
System.out.println("线程"
+ Thread.currentThread().getName()
+ "即将到达饭点3看，当前已有 "
+ (cb.getNumberWaiting() + 1)
+ "个已经到达,"
+ (cb.getNumberWaiting() == 2 ? "人来起了，开饭了！"
: "等候其他人..."));
cb.await();

} catch (Exception e) {
e.printStackTrace();
}
}
};
threadpool.execute(runnable);
}
threadpool.shutdown();

}

}

多线程的同步工具(CyclicBarrier)