import java.util.Collection;

import java.util.Iterator;

import java.util.LinkedList;

import java.util.Queue;

/**

* 固定长度队列

*

*/

public class LimitQueue implements Queue{

//队列长度

private int limit;

Queue queue = new LinkedList();

public LimitQueue(int limit){

this.limit = limit;

}

/**

* 入队

* @param e

*/

@Override

public boolean offer(E e){

if(queue.size() >= limit){

//如果超出长度,入队时,先出队

queue.poll();

}

return queue.offer(e);

}

/**

* 出队

* @return

*/

@Override

public E poll() {

return queue.poll();

}

/**

* 获取队列

* @return

*/

public Queue getQueue(){

return queue;

}

/**

* 获取限制大小

* @return

*/

public int getLimit(){

return limit;

}

@Override

public boolean add(E e) {

return queue.add(e);

}

@Override

public E element() {

return queue.element();

}

@Override

public E peek() {

return queue.peek();

}

@Override

public boolean isEmpty() {

return queue.size() == 0 ? true : false;

}

@Override

public int size() {

return queue.size();

}

@Override

public E remove() {

return queue.remove();

}

@Override

public boolean addAll(Collection extends E> c) {

return queue.addAll(c);

}

@Override

public void clear() {

queue.clear();

}

@Override

public boolean contains(Object o) {

return queue.contains(o);

}

@Override

public boolean containsAll(Collection> c) {

return queue.containsAll(c);

}

@Override

public Iterator iterator() {

return queue.iterator();

}

@Override

public boolean remove(Object o) {

return queue.remove(o);

}

@Override

public boolean removeAll(Collection> c) {

return queue.removeAll(c);

}

@Override

public boolean retainAll(Collection> c) {

return queue.retainAll(c);

}

@Override

public Object[] toArray() {

return queue.toArray();

}

@Override

public T[] toArray(T[] a) {

return queue.toArray(a);

}

}

package com.gary.test;

import com.gary.util.LimitQueue;

public class TestQueue {

public static void main(String[] args) {

LimitQueue lqueue = new LimitQueue(3);

lqueue.offer("1");

lqueue.offer("2");

lqueue.offer("3");

lqueue.offer("4");

//1因超出队列大小限制已自动出队,输出结果为2,3,4

for (String string : lqueue.getQueue()) {

System.out.println(string);

}

}

}