Condition定義了等待/通知兩種類型的方法,下面通過有界隊列的示例示範Condition的用法(多線程中經典的生産-消費者模型)
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class BoundedQueue<T> {
private Object[] items;
private int addIndex, removeIndex, count;
private Lock lock = new ReentrantLock();
//Condition 對象通過lock擷取的
private Condition notEmpty = lock.newCondition();
private Condition notFull = lock.newCondition();
public BoundedQueue(int size) {
items = new Object[size];
}
public void add(T t) throws InterruptedException {
lock.lock();
try {
while (count == items.length)
notFull.await();
items[addIndex] = t;
if (++addIndex == items.length)
addIndex = 0;
++count;
notEmpty.signal();
} finally {
lock.unlock();
}
}
public T remove() throws InterruptedException {
lock.lock();
try {
while (count == 0)
notEmpty.await();
Object x = items[removeIndex];
if (++removeIndex == items.length)
removeIndex = 0;
--count;
notFull.signal();
return (T) x;
} finally {
lock.unlock();
}
}
}