LinkedList实现原理

 1 package cn.bjext.collection;
 2 
 3 public class Node {
 4     Node previous;
 5     Object obj;
 6     Node next;
 7    
 8    public Node(){}
 9    
10 public Node(Node previous, Object obj, Node next) {
11     super();
12     this.previous = previous;
13     this.obj = obj;
14     this.next = next;
15 }
16 
17 public Object getPrevious() {
18     return previous;
19 }
20 public void setPrevious(Node previous) {
21     this.previous = previous;
22 }
23 public Object getObj() {
24     return obj;
25 }
26 public void setObj(Object obj) {
27     this.obj = obj;
28 }
29 public Object getNext() {
30     return next;
31 }
32 public void setNext(Node next) {
33     this.next = next;
34 }
35 }

package cn.bjext.collection;

public class SxtLinkedList {
           private Node first;
           private Node last;
           
           private int size;
           /*
            * 获得双向链表的长度
            */
           public int size(){
               return size;
           }
           
           /*
            * 实现添加对象
            */
           public void add(Object obj)
           {
               Node n=new Node();
               if(first==null)
               {
                   n.setPrevious(null);
                   n.setObj(obj);
                   n.setNext(null);
                   
                   first=n;
                   last=n;
               }else
               {
                   n.setPrevious(last);
                   n.setObj(obj);
                   n.setNext(null);
                   
                   last.setNext(n);
                   last=n;
               }
               size++;
           }

           public void add(int index,Object obj)
           {
              Node temp=node(index);
              Node newNode=new Node();
              newNode.obj=obj;
              
              if(temp!=null)
              {
                  Node up=temp.previous;
                  up.next=newNode;
                  newNode.previous=up;
                  newNode.next=temp;
                  temp.previous=newNode;
                  size++;
              }
               
           }
           //获得对象
           public Object get(int index)
           {
               Node temp=node(index);
               return temp.obj;
           }
           
           /*
            * 删除指定对象的值
            */
           public void remove(int index){
               Node temp=node(index);
               
               if(temp!=null)
               {
                  Node up=new Node();
                  Node down=new Node();
                  up=temp.previous;
                  down=temp.next;
                  
                  up.next=down;
                  down.previous=up;
                  size--;
               }
           }
           
           
           public Node node(int index){
              Node temp=new Node();
              if(first!=null)
          {
                  if(index<(size>>1))
              {
                  temp=first;
                  
                  for(int i=0;i<index;i++)
                  {
                      temp=temp.next;
                  }
              }else{
                  temp=last;
                  for(int i=size-1;i>index;i--)
                  {
                      temp=temp.previous;
                  }
              }
          }
               return temp;
           }
           
           public static void main(String[] args) {
              SxtLinkedList list=new SxtLinkedList();
              list.add("444");
              list.add("5555");
              list.add("555");
              list.add("woshi");
              list.add("liu");
              list.add("xue");
           System.out.println(list.get(0));
        }
}