要實現的功能：執行緒A將一個數據放入佇列，然後通知B進行處理，B處理完後再通知A放一個數據入佇列。

package javathreadlearn;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import java.util.stream.Collectors;


public class ReentrantLockTest {
    public static ReentrantLock lock = new ReentrantLock();
    public static Condition condition = lock.newCondition();
    public static LinkedList<String> queue = new LinkedList<>();
    public static boolean hasCompleted = false;
    public static void main(String[] args){
        ThreadA a = new ThreadA();
        ThreadB b = new ThreadB();
        b.setName("thread-B");
        a.start();
        b.start();
        try {
            a.join();
        }catch (InterruptedException e){
            e.printStackTrace();
        }
    }
}
class ThreadA extends Thread{
    @Override
    public void run(){
        for (int i = 0;i<10;i++) {
            try{
                ReentrantLockTest.lock.lock();
                while (ReentrantLockTest.hasCompleted == true){
                    ReentrantLockTest.condition.await();
                }
                ReentrantLockTest.queue.add(String.valueOf(i));
                ReentrantLockTest.hasCompleted = true;
                ReentrantLockTest.condition.signal();
            } catch (InterruptedException e){
                e.printStackTrace();
            }finally
            {
                ReentrantLockTest.lock.unlock();
            }
        }
    }

}
class ThreadB extends Thread{
    @Override
    public void run(){
        while (true) {
            try{
                ReentrantLockTest.lock.lock();
                while (ReentrantLockTest.hasCompleted == false){
                    ReentrantLockTest.condition.await();
                }
                System.out.println(ReentrantLockTest.queue.remove());
                ReentrantLockTest.hasCompleted = false;
                ReentrantLockTest.condition.signal();
            } catch (InterruptedException e){
                e.printStackTrace();         
            }finally
            {
                ReentrantLockTest.lock.unlock();
            }
            
        }
    }
}

 

 程式碼執行結果如下所示：

0
1
2
3
4
5
6
7
8
9
A-exit

可以看到，A結束了，但是B還是在執行。如何解決呢？

可以用 interrupt來打標記。然後在B執行緒中檢測標記，如果結束就退出迴圈。