2集知识点

1. 手写Linklist的常用方法：

   1. add(Object obj)

   2. add(int index,Object obj)

   3. size()

   4. get(int index)

   5. rangCheck(int index)

   6. remove(int index)

   7. node(int index)

演示代码

package com.collection;

public class Node {
        Node previous;  //这里没加private是为了方便演示，应该加
        Object obj;     //这里没加private是为了方便演示，应该加        Node next;   //这里没加private是为了方便演示，应该加

        
        public void setPrevious(Node previous){
            this.previous = previous;
        }
        
        public Object getPrevious(){
            return previous;
        }
        
        public void setObj(Object obj){
            this.obj = obj;
        }
        
        public Object getObj(){
            return obj;
        }
        
        public void setNext(Node next){
            this.next = next;
        }
        
        public Object getNext(){
            return next;
        }
        
        
        
}

package com.collection;

import java.util.List;

public class SxtLinkedList /*implements List*/ {
    private Node first;
    private Node last;
    private int size;

    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 {
            //直接往last节点后增加新的节点
            n.setPrevious(last);
            n.setObj(obj);
            n.setNext(null);
            
            last.setNext(n);
            last = n;
        }
        size++;
    }
    
    public int size(){
        return size;
    }
    
    public Object get(int index){
        rangeCheck(index);
        Node temp = node(index);
        if(temp!=null){
            return temp.obj;
        }
        return null;
    }
    
    public void rangeCheck(int index){
        if(index<0||index>size){
            try {
                throw new Exception();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    
    public void remove(int index){
        Node temp = node(index);
        if(temp!=null){
            Node up = temp.previous;
            Node down = temp.next;
            up.next = down;
            down.previous = up;
            size--;
        }    
    }
    
    public Node node(int index){
        Node temp = null;
        if(first!=null){
            temp = first;
            for(int i=0;i<index;i++){
                temp = temp.next;
            }
        }
        return temp;
    }
    
    public void add(int index,Object obj){
        Node temp = node(2);
        Node newNode = new Node();
        newNode.obj = obj;
        
        if(temp!=null){
            Node up = temp.previous;
            up.next = newNode;
            newNode.previous = up;
            temp.previous = newNode;
            newNode.next = temp;
            
            size++;
        }
    }
    
    public static void main(String[] args){
        SxtLinkedList list = new SxtLinkedList();
        list.add("aaa");
        list.add("bbb");
        list.add(1,"BBB");
        list.add("ccc");
        System.out.println(list.size());
        //list.remove(1);
        System.out.println(list.get(1));
        
    }

    



}