不同类别中不同类型的数据

public class Node
{
    Node next, child;
    String data;

    Node()
    {
        this(null);
    }

    Node(String s)
    {
        data = s;
        next = child = null;
    }

    Node get(int n)
    {
        Node x = this;
        for(int i=0; i<n; i++)
            x = x.next;
        return x;
    }

    int length()
    {
        int l;
        Node x = this;
        for(l=0; x!=null; l++)
            x = x.next;
        return l;
    }

    void concat(Node b)
    {
        Node a = this.get(this.length() - 1);
        a.next = b;
    }

    void traverse()
    {
        Node x = this;
        while(x!=null)
        {
            System.out.println(x.data);
            x = x.next;
        }
    }
}

class IntegerNode extends Node
{
    int data;

    IntegerNode(int x)
    {
        super();
        data = x;
    }
}

Is there any way I can have different types of data in the two classes so that I can use the IntegerNode class with numbers and the Node class with Strings?

有没有办法在两个类中可以有不同类型的数据，这样我就可以使用带有数字的IntegerNode类和带有字符串的Node类？

Example:

例：

public class Test
{
    public static void main(String args[])
    {
        IntegerNode x = new IntegerNode(9);
        IntegerNode y = new IntegerNode(10);
        x.concat(y);
        x.concat(new Node("End"));
        x.traverse();
    }
}

Right now, this is the output I'm getting: null null End

现在，这是我得到的输出：null null结束

Any explanation would help. Thank you in advance.

任何解释都会有帮助。先谢谢你。

1 个解决方案

#1

The default way would be to use generics.

默认方式是使用泛型。

Like:

喜欢：

public class Node <T> {
  private final T data;

  public Node(T data) { this.data = data; }

to then use like:

然后使用像：

Node<Integer> intNode = new Node<>(5);
Node<String> stringNode = new Node<>("five");

Please note: the above is how you solve such problems in Java. Using inheritance here would a rather wrong approach. Unless you would really find a good reason to be able to concat() nodes with different data. As my solution fully "separates" a Node<Integer> form a Node<String>. And yes, that means that users could create Node<Whatever> objects at any time.

请注意：以上是您在Java中解决此类问题的方法。在这里使用继承将是一种相当错误的方法。除非你真的找到一个很好的理由能够用不同的数据连接（）节点。当我的解决方案完全“分离”Node 形成Node 。是的，这意味着用户可以随时创建Node 对象。

Thus: if you really want only Integer and String data nodes - then you would actually do the following:

因此：如果您真的只想要Integer和String数据节点 - 那么您实际上会执行以下操作：

make the base Node class hold data as Object
使基本Node类将数据保存为Object
make the base class abstract
使基类抽象化
create two specific subclasses for Integer/String, as outlined in the other answer
为Integer / String创建两个特定的子类，如另一个答案中所述

But the question would be: what happens when you decide next week that you want Float and Double, too. And maybe Dates? Then you would have to create new subclasses each time. Leading to a lot of duplicated code.

但问题是：当你下周决定你想要Float和Double时会发生什么。也许日期？然后，您每次都必须创建新的子类。导致大量重复的代码。

So the real answer here: really think your requirements through. Understand what is exactly that you want to build. And then see which path you should take.

所以真正的答案在这里：真的认为你的要求通过。了解您想要构建的内容。然后看看你应该走哪条路。

#1