Question

我正在尝试在最后一个链接列表中添加数据。这是我的代码。这是我的链接列表类：

public class LinkedList {
        Node head;

        private static class Node {
            int data;
            Node pointer;

            public Node(int data) {
                this.data=data;
                pointer=null;
            }
        }

此方法用于在最后添加数据。

  public void append(int new_data){
        Node new_node=new Node (new_data);

        if (head==null){
            head=new Node(new_data);

        }
        Node last_node=head;
         new_node.pointer=null;
        while (last_node.pointer !=null){
            last_node=last_node.pointer;
            last_node.pointer=new_node;

        }
     }

这种方法是打印数据。

public void printData(){
    Node print_Node;
    print_Node=head;
    while (print_Node !=null){
        System.out.print(print_Node.data+" ");
        print_Node=print_Node.pointer;
    }

}

public static void main(String[] args) {
    LinkedList obj=new LinkedList();

    obj.append(10);
    obj.append(100);
    obj.printData();

  }
}

我的代码中的问题在哪里？它只打印10.

Answer 1

你的问题在这里：

while (last_node.pointer !=null){
  last_node=last_node.pointer;
  last_node.pointer=new_node; // this line ... bad!

您正在使用last_node来迭代列表中的所有节点。而你正在迭代;您正在设置所有这些节点的指针...指向新创建的节点。但是当你到达列表末尾时，你应该只做一次！

不确定为什么会让您第一次进入;但是，你追加的代码绝对不正确。

Answer 2

尝试这个

public class linked_list {

Node head;

private static class Node

{
    int data;
    Node pointer;

    public Node(int data)
    {
        this.data = data;
        pointer = null;
    }
}

    public void append(int new_data)
    {
        Node new_node = new Node(new_data);
        //new_node.pointer = null;  No need to set pointer to null as it is already null in your constructor.

        if (head == null)
        {
            head = new Node(new_data);
        }

        Node last_node = head; // Its okay To not change head , good practise.
        while (last_node.pointer != null)
        {
            last_node = last_node.pointer;
        }
        // I think here was the error, your the linked list was not adding only one element , Because while loop
       // got terminated just it reaches null i.e not executing the below line.
        // So put it after while loop, wen you have reached the NULL.
        last_node.pointer = new_node; // line ERROR

    }
    public void printData(){
        Node print_Node;
        print_Node=head;
        while (print_Node !=null){
            System.out.print(print_Node.data+" ");
            print_Node = print_Node.pointer;
        }

    }
    public static void main(String[] args)
    {
        linked_list obj=new linked_list();

        obj.append(10);
        obj.append(100);
        obj.append(898);
        obj.append(8334);
        obj.append(118334);
        obj.append(833400);
        obj.append(83340043);

        obj.printData();

    }

}

最后在链表中添加数据

2 个答案: