带头节点的单向链表反转

package LinkedListReverse;

/**
 * @author Mzh
 * @date 2020-07-09 09:22
 * @description:mzh
 * @version: 1
 */

public class ReverseList {
    private Node head =new Node(0,null);
    private Integer size=0;

    public void add(Node node) throws Exception {
        Node tmp=head;
        while(head.next!=null){
            if (tmp.next.val.equals(node.val)){
                throw new Exception("重复");
            }
            tmp= tmp.next;
        }
        tmp.next=node;
        size++;
    }
    public void show(){
        Node tmp=head;
        while (tmp!=null){
            System.out.println(tmp);
            tmp=tmp.next;
        }
    }
    public void reverse(){
        Node cur=head.next;
        Node tmp=head.next;
        Node newHead=new Node(0,null);
        while(tmp!=null){
            tmp=cur.next;
            cur.next=newHead.next;//就是先把新数组结到当前，当前节点在最前面了
            newHead.next=cur;//赋值回newhead，相当于在newhead和已经添加的到newhead元素之间，取添加新的
//            cur=cur.next;//这是不行的，因为cur已经被手边到新的list
            cur=tmp;//这就是提前保存tmp的作用。
        }

        head.next=newHead.next;
    }

    public static void main(String[] args) {
        ReverseList reverseList=new ReverseList();
        for (int i = 1; i <=10 ; i++) {
            try {
                reverseList.add(new Node(i));
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }
        }

        reverseList.show();
        reverseList.reverse();
        System.out.println("===============================");
        reverseList.show();
    }
}

class Node{
    public Integer val;
    public Node next;

    public Node() {
    }

    public Node(Integer val, Node next) {
        this.val = val;
        this.next = next;
    }
    public Node(Integer val) {
        this.val = val;
    }

    @Override
    public String toString() {
        return "Node{" +
                "val=" + val +
                ", next=" + next +
                '}';
    }
}