java实现数据结构-双向链表

package doubleendlinklist;

/**
 * 
 *
Title:Node
 *
Description:节点
 *
Company:
 
 *@author mym
 *@date 2017-7-9下午7:41:16
 *@version
 */
public class DoubleNode {

	public long data;		//节点数据
	
	public DoubleNode next;		//下一个节点
	
	public DoubleNode previous;	//上一个结点
	
	public DoubleNode(long value){
		this.data = value;
	}
	
	/**
	 * 
	 *
title:display
	 *
function:显示当前表头数据
	 *@author mym
	 */
	public void display(){
		System.out.print(data + " ");
	}
}


//双向实现
package doubleendlinklist;

public class DoubleLinkList {
	
	//public 
	private DoubleNode first;		//头节点
	
	private DoubleNode end;			//尾结点
	
	public DoubleLinkList(){
		first = null;
		end = null;
	}
	
	/**
	 * 在头节点后进行插入结点
	 */
	public void insertFirst(long value){
		DoubleNode node = new DoubleNode(value);
		if(isEmpty()){
			end = node;
		}else{
			first.previous = node;
			node.next = first;
			
		}
		
		first = node;
	}
	
	/**
	 * 在尾部添加结点
	 */
	public void insertEnd(long value){
		DoubleNode node = new DoubleNode(value);
		
		if(isEmpty()){
			first = node;
		}else{
			end.next = node;			
			node.previous = end;		//双向指向
		}
		
		end = node;
	}
	
	
	/**
	 *从头节点删除，修改first的值
	 */
	public DoubleNode deleteFirst(){
		DoubleNode currentNode = first;
		
		if(currentNode.next != null){
			currentNode.next.previous = null;
			
		}else{
			end = null;
		}
		
		first = currentNode.next;
		return currentNode;
	}
	
	/**
	 * 从尾部进行删除，修改end的值
	 */
	public DoubleNode deleteEnd(){
		DoubleNode currentNode = end;
		
		if(currentNode.previous != null){
			currentNode.previous.next = null;
		}else{
			first = null;
		}
		
		end = currentNode.previous;
		return currentNode;
	}
	
	/**
	 * 显示所有
	 */
	public void display(){
		DoubleNode currentNode = first;
		while(currentNode != null){
			currentNode.display();
			currentNode = currentNode.next;		//指针后移一位
		}
		System.out.println(); 					//换行
	}
	
	
	/**
	 * 根据数据查找
	 */
	public DoubleNode find(long value){
		DoubleNode currentNode = first;
		while(currentNode.data != value){
			if(currentNode.next == null){
				return null;
			}
			currentNode = currentNode.next;
		}
		
		return currentNode;
	}
	
	
	
	
	/**
	 * 根据数据值删除
	 */
	public DoubleNode deleteByValue(long value){
		DoubleNode currentNode = first;
		
		if(currentNode == first){
			end = null;
		}
		
		if(currentNode !=null){
			while(currentNode.data != value && currentNode.next != null){
				currentNode = currentNode.next;
			}	
		
				
		}
		
		currentNode.previous.next = currentNode.next;
		currentNode.next.previous = currentNode.previous;			//双向指向
		
		
		return currentNode;
	}
	
	/**
	 * 是否为空
	 */
	public boolean isEmpty(){
		return first == null;
	}
}