不带头非循环的单向链表的增删查改的实现(代码版)

public class MySingList {
    //定义一个内部类
    class Node{
        public int val;
        public Node next;
        public Node(int val) {
            this.val = val;
        }
    }
    public Node head;
    public void createList(){
        Node node1 =new Node(10);
        Node node2 =new Node(12);
        Node node3=new Node(14);
        Node node4=new Node(16);
        node1.next=node2;
        node2.next=node3;
        node3.next=node4;
        Node head=node1;
    }
    //头插法,就是在链表的头结点前面插入一个元素
    public void addFirst(int data){
        Node node= new Node(data);
        node.next=head;
        head=node;
    }
    //尾插法
    public void addLast(int data){
        Node node =new Node(data);
        Node cur=head;
        if(head==null){
            head=node;
            return ;
        }
        while(cur.next!=null){
            cur=cur.next;
        }
        cur.next=node;
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index, int data) throws  IndexOutOfException{
        Node node =new Node(data);
        //判断插入元素的下标是不是合法的
        isVaildIndex(index);
        if(index==0) {
            addFirst(data);
            return;
        }
            if(index==size()){
                addLast(data);
                return;
            }
           Node cur= findPlace(index);
           node.next=cur.next;
           cur.next=node;
    }
    //得找到走index-1步的地址
    private Node  findPlace(int index){
        int count=0;
        Node cur=head;
        while(count!=index-1){
            count++;
            cur=cur.next;
        }
        return cur;
    }
    private void isVaildIndex(int index) throws  IndexOutOfException{
        if(index<0||index>size()){
            throw new IndexOutOfException("index位置不合法");
        }
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        Node cur=head;
        while(cur!=null){
            if(cur.val==key){
                return true;
            }
            cur=cur.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        if(head==null){
        return;
    }
        if(head.val==key){
            head=head.next;
            return;
        }
        Node cur=findPlace1(key);//删除结点的前驱结点
        if(cur==null){
            return;
        }
        Node del=cur.next;//要删除的结点
        cur.next=del.next;//完成删除了
    }
    //找到key结点的前一个结点的地址
    private Node findPlace1(int   key){
        Node cur=head;
        while(cur.next!=null){
            if(cur.next.val==key){
                return cur;
            }
            cur=cur.next;
        }
        return null;
    }
    //删除所有值为key的节点
    public void removeAllKey(int key) {
        if (head == null) {
            return;
        }
        Node prev = head;
        Node cur = head.next;
        while (cur != null) {
            if (cur.val == key) {
                prev.next = cur.next;
                cur = cur.next;
            } else {
                prev = cur;
                cur = cur.next;
            }
        }
        if(head.val==key){
            head=head.next;
        }
    }
    //得到单链表的长度
    public int size(){
        Node cur=head;
        int count=0;
        while (cur!=null){
            count++;
            cur=cur.next;
        }
        return  count;
    }
    public void display(){
        Node cur=head;
        while (cur!=null){
            System.out.println(cur.val+"");
            cur=cur.next;
        }
    }
    public void clear(){
        head=null;
    }
}