Java-闭锁和栅栏的区别

Question

在看Java并发编程实战之后，看到了闭锁和栅栏，我总是觉得他们是差不多的，但书上说的是闭锁用于等待事件，栅栏用于等待线程，有无哪位大侠可以举个简单的例子，让我区别下，加深对它们的理解。

Answer 1

写了两个很简单的例子

@Test
public void test123423() throws Exception {
final int N=5;
final CountDownLatch startSignal = new CountDownLatch(1);
final CountDownLatch doneSignal = new CountDownLatch(N);
final Random r=new Random();
for (int i = 0; i < N; ++i)
new Thread(new Runnable() {
@Override
public void run() {
try {
startSignal.await();
System.out.println(Thread.currentThread().getName()+" starts!");
Thread.sleep(r.nextInt(5000));
System.out.println(Thread.currentThread().getName()+" done!");
} catch (Exception e) {}
doneSignal.countDown();
}
}).start();
System.out.println("All workers start!");
startSignal.countDown();
doneSignal.await();
System.out.println("All workers done!");
}

@Test
public void test2324() throws Exception{
final int N=5;
final AtomicInteger counter=new AtomicInteger(25);
final CyclicBarrier barrier=new CyclicBarrier(N);
final Random r=new Random();
for(int i=0;i<N;i++)
new Thread(new Runnable(){
@Override
public void run() {
while(counter.getAndDecrement()>0){
System.out.println(Thread.currentThread().getName()+" starts!");
try {
Thread.sleep(r.nextInt(2000));
System.out.println(Thread.currentThread().getName()+" done!");
barrier.await();
} catch (Exception e) {}
}
}
}).start();
do{
Thread.sleep(5000);
}while(counter.get()>0);
}