Java集合源码学习(13)_Queue接口以及基础实现AbstractQueue

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1:Queue接口

继承接口Collection；

通常而言，顺序是FIFO，例外是优先级队列（顺序由指定的Comparator来决定）和栈(LIFO)
增加了下面几个方法：

Throws exceptionReturns special valueInsertadd(e)offer(e)Removeremove()poll()Examineelement()peek()

2:AbstractQueue

add()、remove()、element()是基于offer()、poll()、peek()来实现的；

代码如下:

public abstract class AbstractQueue<E> extends AbstractCollection<E> implements Queue<E> {protected AbstractQueue() {}public boolean add(E e) {if (offer(e))return true;elsethrow new IllegalStateException("Queue full");}public E remove() {E x = poll();if (x != null)return x;elsethrow new NoSuchElementException();}public E element() {E x = peek();if (x != null)return x;elsethrow new NoSuchElementException();}public void clear() {while (poll() != null);}public boolean addAll(Collection<? extends E> c) {if (c == null)throw new NullPointerException();if (c == this)throw new IllegalArgumentException();boolean modified = false;Iterator<? extends E> e = c.iterator();while (e.hasNext()) {if (add(e.next()))modified = true;}return modified;}}

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