关于多线程问题，signalAll,await问题

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关于多线程问题，signalAll,await问题3

package ThreadTest;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.locks.Condition;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReentrantLock;

public class AwaitTest1 extends Thread{

private final Lock lock = new ReentrantLock();

private Condition waitCondition = lock.newCondition();

public static void main(String[] args) throws InterruptedException {

new AwaitTest1().threads();

}

public void threads() throws InterruptedException {

Thread t1 = new Thread(){

public void run(){

try {

lock.lock();

System.out.println("do somthing xxx long time");

waitCondition.signalAll();

System.out.println("sign other");

Thread.sleep(500);

lock.unlock();

} catch (InterruptedException e) {

e.printStackTrace();

}

};

Thread t2 = new Thread(){

public void run(){

System.out.println(waitResult());

}

};

t1.start();

t2.start();

}

public Boolean waitResult() {

System.out.println("x");

lock.lock();

Boolean result = false;

try {

System.out.println("y");

result = waitCondition.await(1000, TimeUnit.MILLISECONDS);

} catch (InterruptedException e) {

e.printStackTrace();

}

lock.unlock();

return result;

}

说下我写这个目的，我也是才学学习多线程，在此遇到了不少问题，我本来想些个异步的通信就是说当我运行线程T1的时候，他唤醒T2，就像是Future那个异步回调，但是不知道该如何写，也不知道这个result什么时候返回true,我感觉是当线程T1完成复杂的计算后，然后在await在没有超时的情况下，会返回为true，但是现在我程序写的有问题，请各位帮忙解决下，谢谢

Java综合

2011年9月26日 10:41

yutao3118639
0
0 0 1

1个答案按时间排序按投票排序

0 0

采纳的答案

要想获得你预期的结果，就必须是
t2先获得锁（lock.lock()),然后执行 waitCondition.await，释放锁并等待信号；t1获得锁执行完相关操作后执行waitCondition.signalAll，t2从而获得锁继续执行，此时如果等待时间未超时就返回true.
await时间应该比t1执行时间长。


import java.util.concurrent.TimeUnit;

import java.util.concurrent.locks.Condition;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReentrantLock;

public class AwaitTest {

	private final Lock lock = new ReentrantLock();

	private Condition waitCondition = lock.newCondition();

	public static void main(String[] args) throws InterruptedException {

		new AwaitTest().threads();

	}

	public void threads() throws InterruptedException {
		final Thread t1 = new Thread() {
			public void run() {
				try {
					lock.lock();
					System.out.println("do somthing...");
					Thread.sleep(1000);
					waitCondition.signal();
				} catch (InterruptedException e) {
					e.printStackTrace();
				} finally {
					lock.unlock();
				}
			}
		};

		Thread t2 = new Thread() {
			public void run() {
				
				System.out.println(waitResult());
				
			}
		};
		

		t2.start();
		//保证t2先开始
		Thread.sleep(1000);
		t1.start();
	}

	public boolean waitResult() {
		boolean result = false;
		lock.lock();
		try {
			result = waitCondition.await(3000, TimeUnit.MILLISECONDS);
		} catch (InterruptedException e) {
			e.printStackTrace();
		} finally {
			lock.unlock();
		}
		return result;
	}

}

2011年9月26日 11:28