算法学习(8)-链表之双端链表

package com.tw.dst.link;

/**
 * <p>链表学习(二):双端链表</p>
 * @author tangw 2010-12-07
 *
 */
public class FirstLastLink {
	private Link first; //第一个链表引用
	private Link last; //最后一个链表引用
	
	//判断是否为空
	public boolean isEmpty(){
		return (first==null);
	}
	//在表前插入一个链结点
	public void insertFirst(int id,double dd){
		Link newLink = new Link(id,dd);
		if(this.isEmpty()){
			last = newLink;
		}
		newLink.next = first;
		first = newLink; 
	}
	//在表尾插入一个链结点
	public void insertLast(int id,double dd){
		Link newLink = new Link(id,dd);
		if(this.isEmpty()){
			first = newLink;
		}
		last.next = newLink;
		last = newLink; 
	}
	
	//删除第一个链结点
	public Link deleteFirst(){
		Link temp = first;
		if(first == null){
			last  = null;
		}
		first = first.next;
		return temp;
	}
	
	//输出链表数据
	public void displayList(){
		System.out.println("list (first-->last)");
		Link current = first;
		while(current!=null){
			current.displayLink();
			current =current.next;
		}
		System.out.println("");
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		//----1---插入
		FirstLastLink linkList = new FirstLastLink();
		linkList.insertFirst(22, 2.99);
		linkList.insertFirst(44, 4.99);
		linkList.insertFirst(66, 6.99);
		
		linkList.displayList();
		//---2---删除
		Link aLink = linkList.deleteFirst();
		linkList.displayList();

	}

}