带你快速搞定java多线程(5)

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

public class CountDownLatchTest {
   private static final int RUNNER_COUNT = 10;
   private static final int CORE_THREAD_COUNT = 10;
   public static void main(String[] args) throws InterruptedException {
       final CountDownLatch begin = new CountDownLatch(1);
       final CountDownLatch end = new CountDownLatch(RUNNER_COUNT);
       final ExecutorService exec = Executors.newFixedThreadPool(CORE_THREAD_COUNT);
       // 启动是个线程
       for (int i = 0; i < RUNNER_COUNT; i++) {
           final int NO = i + 1;
           Runnable run = () -> {
               try {
                   // 主线程 begin 之后所有的线程才会开始运行
                   begin.await();
                   Thread.sleep((long)(Math.random() * 10000));
                   System.out.println("No." + NO + " arrived");
              } catch (InterruptedException e) {
                   e.printStackTrace();
              } finally {
                   // 当前线程结束
                   end.countDown();
              }
          };
           exec.submit(run);
      }
       System.out.println("Game Start ...");
       begin.countDown();
       // 等待其他的线程结束
       end.await();
       System.out.println("Game Over.");
       exec.shutdown();
  }
}

private static final class Sync extends AbstractQueuedSynchronizer {
      private static final long serialVersionUID = 4982264981922014374L;
      Sync(int count) {
          setState(count);
      }
      int getCount() {
          return getState();
      }
      protected int tryAcquireShared(int acquires) {
          return (getState() == 0) ? 1 : -1;
      }
      protected boolean tryReleaseShared(int releases) {
          // Decrement count; signal when transition to zero
          for (;;) {
              int c = getState();
              if (c == 0)
                  return false;
              int nextc = c-1;
              if (compareAndSetState(c, nextc))
                  return nextc == 0;
          }
      }
  }