【JAVA 单链表】反转单列表

节点类：

class ListNode {
    public int data; //data可以是任何类型
    public ListNode next;

    public ListNode(int data) {
        this.data = data;
        this.next = null;
    }
}

class TestDemon1 {

    public ListNode head; //定义头部

    public TestDemon1() {
        this.head = null;
    }
//单链表

    //尾插法
    private void addFirst(int data) {
        ListNode node=new ListNode(data);
        if(this.head==null){ //头为空
            this.head=node;
        }else{
            node.next=this.head;
            this.head=node;
        }
    }

   //反转单链表
   public ListNode reserveList(){
        ListNode cur=this.head;
        ListNode pre=null;
        ListNode newHead=null;
        while (cur!=null){
            ListNode curNext=cur.next;
            if(curNext==null){
                newHead=cur;
            }else {  //开始反转
                cur.next=pre;
                pre=cur;
                cur=curNext;
            }
        }
        return newHead;
    }

    
    //打印单链表
    public void display() {
        ListNode cur = this.head;
        while (cur != null) {
            System.out.print(cur.data + " ");
            cur = cur.next;
        }
        System.out.println();
    }
    public void display2(ListNode newHead) {
        ListNode cur = newHead;
        while (cur != null) {
            System.out.print(cur.data + " ");
            cur = cur.next;
        }
        System.out.println();
    }
   
 public static void main(String[] args) {
        TestDemon1 mySignalList = new TestDemon1();
        mySignalList.addFirst(1);
        mySignalList.addFirst(2);
        mySignalList.addFirst(3);
        mySignalList.addFirst(4);
        mySignalList.addFirst(5);
        mySignalList.display();

       ListNode node=mySignalList.reserveList();
       mySignalList.display2(node);

    }

}

运行结果：