为何ArrayBlockingQueue中的ReentranLock对象无需实例化？
来源：5-1 总结及展望
阿Dine
2018-09-08 19:26
public class ArrayBlockingQueue<E> extends AbstractQueue<E>
implements BlockingQueue<E>, java.io.Serializable {
final Object[] items;
int takeIndex;
int putIndex;
int count;
final ReentrantLock lock; /**notEmpty条件对象，用于通知take方法队列已有元素，可执行获取操作 */
private final Condition notEmpty;
private final Condition notFull; 迭代器 */
transient Itrs itrs = null;
public void put(E e) throws InterruptedException {
checkNotNull(e);
final ReentrantLock lock = this.lock; // ？？？？？？？？
lock.lockInterruptibly();
try {
while (count == items.length) //将当前调用线程挂起，添加到notFull条件队列中等待唤醒
notFull.await();
enqueue(e);//如果队列没有满直接添加。。 } finally {
lock.unlock();
}
}
}为甚么类的属性里没有ReentrantLock lock = new ReentrantLock();
却可以在put()中直接指定ReentrantLock lock=this.lock;?
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- leopoincare
- 2018-09-10 15:52:00
/** * Creates an {@code ArrayBlockingQueue} with the given (fixed) * capacity and the specified access policy. * * @param capacity the capacity of this queue * @param fair if {@code true} then queue accesses for threads blocked * on insertion or removal, are processed in FIFO order; * if {@code false} the access order is unspecified. * @throws IllegalArgumentException if {@code capacity < 1} */ public ArrayBlockingQueue(int capacity, boolean fair) { if (capacity <= 0) throw new IllegalArgumentException(); this.items = new Object[capacity]; lock = new ReentrantLock(fair); notEmpty = lock.newCondition(); notFull = lock.newCondition(); }构造方法里面初始化了lock对象
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