java版数据结构与算法—链表实现队列

package com.zoujc.QueueLink;

/**
 * 链表实现队列
 */
class FirstLastList {
    private Link first;
    private Link last;
    public FirstLastList(){
        first = null;
        last = null;
    }
    //判空
    public boolean isEmpty(){
        return first == null;
    }
    //插入
    public void insertLast(int dd){
        Link link = new Link(dd);
        if(isEmpty()){
            first = link;
        }else {
            last.next = link;
        }
        last = link;
    }
    //删除
    public int deleteFirst(){
        int temp = first.dData;
        if(first.next == null){
            last = null;
        }
        first = first.next;
        return temp;
    }
    //显示
    public void displayList(){
        Link link = first;
        while (link != null){
            link.display();
            link = link.next;
        }
        System.out.println("");
    }
}
class Link{
    public int dData;
    public Link next;
    public Link(int dd){
        dData = dd;
    }
    public void display(){
        System.out.print(dData + " ");
    }
}
class LinkQueue{
    private FirstLastList theList;
    public LinkQueue(){
        theList = new FirstLastList();
    }
    //判空
    public boolean isEmpty(){
        return theList.isEmpty();
    }
    //插入，从末尾插入
    public void insert(int value){
        theList.insertLast(value);
    }
    //删除
    public int remove(){
        return theList.deleteFirst();
    }
    //显示
    public void displayQueue(){
        System.out.print("Queue:");
        theList.displayList();
    }
    public static void main(String[] args){
        LinkQueue linkQueue = new LinkQueue();
        linkQueue.insert(20);
        linkQueue.insert(66);
        linkQueue.insert(99);
        linkQueue.insert(55);
        linkQueue.displayQueue();
        linkQueue.remove();
        linkQueue.remove();
        linkQueue.displayQueue();
    }
}