实现双向链表

class Node{
    int data;
    Node next;
    Node(int data){
        this.data=data;
    }
}
public class MyNodes {
    private Node head;
    private Node last;
    private int size;
    public Node get(int index){
        if(index<0 || index>=size){
            return  null;
        }
        Node temp=head;
        for (int i=0;i<index ; i++){
            temp=temp.next;
        }
        return temp;
    }
    public void insert(int data,int index) throws Exception{
        if(index<0 || index>size){
            throw new IndexOutOfBoundsException("超出链表节点范围");
        }
        Node insertNode=new Node(data);
        if(size==0){
            head=insertNode;
            last=insertNode;
        }else if(index==0){
            //头部插入
            insertNode.next=head;
            head=insertNode;
        }else if(index==size){
            //尾部插入
            last.next=insertNode;
            last=insertNode;
        }else{
            //中间插入
            Node prevNode=get(index-1);
            Node nextNode=get(index);
            prevNode.next=insertNode;
            insertNode.next=nextNode;
        }
        size++;
    }
    public void remove(int index)throws Exception{
        if(index<0 || index>size)throw new Exception("超出范围");
        if(index==0){
            //删除首元素
            head=head.next;
        }else if(index==size-1){
            Node temp =get(index-1);
            last=temp;
            last.next=null;
            temp.next=null;
        }else{
            //删除中间元素
            Node Pre_temp=get(index-1);
            Node Last_temp=get(index+1);
            Pre_temp.next=Last_temp;
        }
        size--;
    }
    public void output(){
        Node temp=head;
        while (temp !=null){
            System.out.println(temp.data);
            temp=temp.next;
        }
    }

}