package NODE.DLNODE;

public class DLNode {
//数据
Object data;
//前驱结点
DLNode prev;
//后驱结点
DLNode next;

public DLNode(Object data, DLNode prev, DLNode next) {
    this.data = data;
    this.prev = prev;
    this.next = next;
}

//头节点指针
static  DLNode head;
//尾节点指针
static DLNode last;

//获取长度
public static int getLength(){
    int count=0;
    for (DLNode n=head; n != null ; n=n.next ) {
        count ++;
    }
    return count;
}

//插入节点
public static void add(Object data, int index) {
    DLNode node=new DLNode(data,null,null);
    //插入头部
    if (index ==0){
        node.next=head;
        head.prev=null;
        head=node;
    }
    //插入尾部
    else if(index == getLength()){
        last.next=node; // 将新的节点与原来的尾部节点进行结构上的关联
        node.prev=last;
        last=node;  // node将成为最后一个节点
    }
    //中间插入
    else {
        int temp=0;
        for (DLNode n=head; n!=null ; n=n.next){
            temp++;
            if (temp ==index){
                node.next=n.next;
                n.next=node;
                node.prev=n;
                break;
            }
        }
    }

}

//删除节点
public static void remove(int index) {
    //删除头部
    if (index ==0){
        head=head.next;
        head.prev=null;
    }
    //尾部删除
    else if(index ==getLength()-1){
        last=last.prev;
        last.next=null;
    }
    //超出链表长度 从0开始的
    else if (index >= getLength()){
        throw new IndexOutOfBoundsException("超出链表长度");
    }
    //删除中间
    else {
        int temp=0;
        for (DLNode n=head; n!=null ; n=n.next){
            temp++;
            if (temp ==index){
                n.next=n.next.next;
                n.next.prev=n;
                break;
            }
        }
    }
}

public static void main(String[] args) {
    DLNode node1 = new DLNode("aaa", null, null);
    DLNode node2 = new DLNode("bbb", node1, null);
    DLNode node3 = new DLNode("ccc", node2, null);
    DLNode node4 = new DLNode("ddd", node3, null);

    node3.setNext(node4);
    node2.setNext(node3);
    node1.setNext(node2);
    head = node1;
    last = node4;


    System.out.print("当前链表：");
    for (DLNode n = head; n != null; n = n.next) {
        System.out.println(n.data + " ");
    }
    add("eee", 2);
    System.out.print("插入后链表：");
    for (DLNode n = head; n != null; n = n.next) {
        System.out.println(n.data + " ");
    }

    remove(2);
    System.out.print("删除后链表：");
    for (DLNode n = head; n != null; n = n.next) {
        System.out.println(n.data + " ");
    }
}

public DLNode() {
}


public Object getData() {
    return data;
}

public void setData(Object data) {
    this.data = data;
}

public DLNode getPrev() {
    return prev;
}

public void setPrev(DLNode prev) {
    this.prev = prev;
}

public DLNode getNext() {
    return next;
}

public void setNext(DLNode next) {
    this.next = next;
}

}