Java数据结构温习之双向双端链表

package com.study.doublelink;


/**
* 节点类
*/
class Link{
public int data;
public Link next;
public Link previous;

public Link(int data){
this.data = data;
this.next = null;
this.previous = null;
}

public void display(){
System.out.println(this.data);
}
}

/**
* 双向双端链表类
*/
class DoubleLinkList{
private Link first;
private Link last;

public DoubleLinkList(){
this.first = null;
this.last = null;
}

public boolean isEmpty(){
return (first == null);
}

public void insertFirst(int data){
Link newLink = new Link(data);
if (isEmpty()){
this.last = newLink;
}else{
this.first.previous = newLink;
}

newLink.next = this.first;
this.first = newLink;
}

public boolean insertAfter(int key, int data){
Link current = this.first;
Link newLink = new Link(data);

while (current.data != key){
current = current.next;
if (current == null){
return false;
}
}

if (current == this.last){
this.last = newLink;
newLink.next = null;
}else{
current.next.previous = newLink;
newLink.next = current.next;
}

current.next = newLink;
newLink.previous = current;
return true;
}

public void display(){
Link current = this.first;
System.out.println("normal: ");
while (current != null){
current.display();
current = current.next;
}
}

public void displayReverse(){
Link current = this.last;
System.out.println("reverse: ");
while (current != null){
current.display();
current = current.previous;
}
}
}


public class DoubleLink {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
DoubleLinkList dll = new DoubleLinkList();
dll.insertFirst(2);
dll.insertAfter(2, 4);
dll.insertAfter(1, 3);
dll.insertAfter(4, 5);

dll.display();
dll.displayReverse();
}
}