java.util.concurrent.locks.Condition接口提供了一个线程暂停执行的能力，直到给定的条件为真. Condition对象必然绑定到Lock并使用newCondition()方法获得.
条件方法
以下是重要的列表Condition类中可用的方法.
| Sr.No. | 方法&说明 |
|---|---|
| 1 | public void await() 导致当前线程等到信号通知或中断为止. |
| 2 | public boolean await(long time，TimeUnit unit) 导致当前线程等到信号通知或中断，或指定的等待时间过去. |
| 3 | public long awaitNanos(long nanosTimeout) 导致当前线程等到信号通知或中断，或者指定的等待时间过去. |
| 4 | public long awaitUninterruptibly() 导致当前线程等到发出信号为止. |
| 5 | public long awaitUntil() 原因当前线程要等到信号通知或中断，或指定的截止日期过去. |
| 6 | public void signal() 唤醒一个等待线程. |
| 7 | public void signalAll() 唤醒所有等待的线程. |
示例
以下TestThread程序演示了Condition接口的这些方法.这里我们使用signal()来通知和await()来挂起线程.
import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;public class TestThread { public static void main(String[] args) throws InterruptedException { ItemQueue itemQueue = new ItemQueue(10); //Create a producer and a consumer. Thread producer = new Producer(itemQueue); Thread consumer = new Consumer(itemQueue); //Start both threads. producer.start(); consumer.start(); //Wait for both threads to terminate. producer.join(); consumer.join(); } static class ItemQueue { private Object[] items = null; private int current = 0; private int placeIndex = 0; private int removeIndex = 0; private final Lock lock; private final Condition isEmpty; private final Condition isFull; public ItemQueue(int capacity) { this.items = new Object[capacity]; lock = new ReentrantLock(); isEmpty = lock.newCondition(); isFull = lock.newCondition(); } public void add(Object item) throws InterruptedException { lock.lock(); while(current >= items.length) isFull.await(); items[placeIndex] = item; placeIndex = (placeIndex + 1) % items.length; ++current; //Notify the consumer that there is data available. isEmpty.signal(); lock.unlock(); } public Object remove() throws InterruptedException { Object item = null; lock.lock(); while(current <= 0) { isEmpty.await(); } item = items[removeIndex]; removeIndex = (removeIndex + 1) % items.length; --current; //Notify the producer that there is space available. isFull.signal(); lock.unlock(); return item; } public boolean isEmpty() { return (items.length == 0); } } static class Producer extends Thread { private final ItemQueue queue; public Producer(ItemQueue queue) { this.queue = queue; } @Override public void run() { String[] numbers = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12"}; try { for(String number: numbers) { System.out.println("[Producer]: " + number); } queue.add(null); } catch (InterruptedException ex) { ex.printStackTrace(); } } } static class Consumer extends Thread { private final ItemQueue queue; public Consumer(ItemQueue queue) { this.queue = queue; } @Override public void run() { try { do { Object number = queue.remove(); System.out.println("[Consumer]: " + number); if(number == null) { return; } } while(!queue.isEmpty()); } catch (InterruptedException ex) { ex.printStackTrace(); } } }}这将产生以下结果.
输出
[Producer]: 1[Producer]: 2[Producer]: 3[Producer]: 4[Producer]: 5[Producer]: 6[Producer]: 7[Producer]: 8[Producer]: 9[Producer]: 10[Producer]: 11[Producer]: 12[Consumer]: null