Java关于队列的自我实现

1.循环队列的封装

package com.pinjia.shop.common.collection;

/**
 * Created by wangwei on 2016/12/29.
 * 循环队列的自我封装
 */
public class Myqueue<E> {
    E[] a;//数组对象
    private static final int DEFAULT_SIZE = 10;//默认队列初始化大小
    int front;
    int rear;
    public Myqueue(){
        this(DEFAULT_SIZE);
    }

    public Myqueue(int size){
        a = (E[])new Object[size];
        front = 0;
        rear = 0;
    }

    public boolean inQueue(E obj){
        if((rear+1)%a.length==front){ //队满
            return false;
        }else{
            a[rear] = obj;
            rear = (rear+1)%a.length;
            return true;
        }
    }

    public E outQueue(){
        if(front == rear){
            return null;
        }else{
            E obj = a[front];
            front = (front+1)%a.length;
            return obj;
        }
    }

    public int length(){
        if(rear>front)
            return rear-front+1;
        else
            return a.length;
    }

    public boolean isEmpty(){
        return rear == front;
    }

    public String toString(){
        StringBuilder sb = new StringBuilder();
        for(int i=0;i<a.length;i++){
            sb.append(outQueue()+""+",");
        }
        return sb.toString().substring(0,sb.toString().lastIndexOf(","));
    }

    public static void main(String[] args) {
        Myqueue<Integer> myqueue = new Myqueue<Integer>(12);
        System.out.println(myqueue.length());
        myqueue.inQueue(1);
        myqueue.inQueue(2);
        myqueue.inQueue(3);
        myqueue.inQueue(4);
        System.out.println(myqueue.toString());
    }

}

2.链式队列的封装

package com.pinjia.shop.common.collection;

import java.util.LinkedList;

/**
 * Created by wangwei on 2016/12/29.
 */
public class LinkedQueue<T> {
    //定义链式数据结构
    private class Node{
        private Node next;
        private T data;
        public Node(){}
        public Node(T data,Node next){
            this.next = next;
            this.data = data;
        }
    }

    private Node front;
    private Node rear;
    private int size = 0;

    public LinkedQueue(){
        Node s = new Node(null,null);
        s.next = null;
        front = rear = s;
    }

    //入队
    public void inQueue(T data){
        Node node = new Node(data,null);
        rear.next = node;
        rear = node;
        size++;
    }

    //出队
    public T outQueue(){
        if(front == rear) //空队列
        return null;
        else{
            Node p = front.next;
            T x = p.data;
            front.next = front.next.next;
            if(p.next==null)rear = front;
            p = null;
            size--;
            return x;
        }
    }

    /**
     * 队列长队
     * @return
     * @author WWX
     */
    public int size(){
        return size;
    }

    /**
     * 判断队列是否为空
     * @return
     * @author WWX
     */
    public  boolean isEmpty(){
        return  size==0;

    }

    public String toString() {
        if(isEmpty()){
            return "[]";
        }else{
            StringBuilder sb = new StringBuilder("[");
            for(Node current=front.next;current!=null;current=current.next){
                sb.append(current.data.toString() + ", ");
            }
            int len = sb.length();
            return sb.delete(len - 2, len).append("]").toString();
        }
    }
    public static void main(String[] args) {
        LinkedQueue<Integer> queue=new LinkedQueue<Integer>();
        queue.inQueue(1);
        queue.inQueue(2);
        queue.inQueue(3);
        queue.inQueue(4);
        queue.inQueue(5);
        queue.inQueue(6);
        System.out.println(queue);
        System.out.println("出队："+queue.outQueue());
        System.out.println("队列长度="+queue.size());
        System.out.println(queue);
        System.out.println("出队："+queue.outQueue());
        System.out.println("队列长度="+queue.size());
        System.out.println(queue);
        System.out.println("出队："+queue.outQueue());
        System.out.println("队列长度="+queue.size());
        System.out.println(queue);
    }
}