比较 Java 中可比较的泛型

Question

我有一个通用二叉树，它会将小于或等于的对象添加到左侧，将大于的对象添加到右侧。我的问题是比较泛型，我知道数据值将是一个对象包装的原语或一个字符串，所以它们是可比较的。但是，我不知道如何在代码中实现它。

代码还在开发中，我知道添加方法还不能正确添加，但我正在努力。谢谢

这是树节点：

public class TreeNode<T>
{
    //Instance Variables
    TreeNode leftChild;
    TreeNode rightChild;
    int childCount;
    int depth;
    T data;


    public TreeNode(T data, int parentDepth)
    {
        leftChild = null;
        rightChild = null;
        childCount = 0;
        depth = parentDepth + 1;
        this.data = data;
    }

    public TreeNode(int parentDepth)
    {
        leftChild = null;
        rightChild = null;
        childCount = 0;
        depth = parentDepth + 1;
        data = null;
    }


    public void add(T data)
    {
        if (this.data.compareTo(data) <= 0)
        {
            addLeft(data);
        } else if (this.data.compareTo(data) > 0)
        {
            addRight(data);
        } else
        {
            System.out.println("ERROR IN TREENODE.ADD");
        }
    }


    public void addLeft(T data)
    {
        leftChild = new TreeNode(data, depth);
    }

    public void addLeft()
    {
        leftChild = new TreeNode(depth);
    }


    public void addRight(T data)
    {
        rightChild = new TreeNode(data, depth);
    }

    public void addRight() {
        rightChild = new TreeNode(depth);
    }
}

Answer 1

I know the data value will be a object-wrapped primitive or a String, so they are comparable.

然后你可以告诉编译器：

public class TreeNode<T extends Comparable<T>>

如果这样做，您将可以访问 Comparable 中定义的 compareTo 方法。

Answer 2

您的 T 应该实现 Comparable 接口以便进行比较。

public class TreeNode<T extends Comparable<T>>
{
    //Instance Variables
    TreeNode leftChild;
    TreeNode rightChild;
    int childCount;
    int depth;
    T data;


    public TreeNode(T data, int parentDepth)
    {
        leftChild = null;
        rightChild = null;
        childCount = 0;
        depth = parentDepth + 1;
        this.data = data;
    }

    public TreeNode(int parentDepth)
    {
        leftChild = null;
        rightChild = null;
        childCount = 0;
        depth = parentDepth + 1;
        data = null;
    }


    public void add(T data)
    {
        if (this.data.compareTo(data) <= 0)
        {
            addLeft(data);
        } else if (this.data.compareTo(data) > 0)
        {
            addRight(data);
        } else
        {
            System.out.println("ERROR IN TREENODE.ADD");
        }
    }


    public void addLeft(T data)
    {
        leftChild = new TreeNode(data, depth);
    }

    public void addLeft()
    {
        leftChild = new TreeNode(depth);
    }


    public void addRight(T data)
    {
        rightChild = new TreeNode(data, depth);
    }

    public void addRight() {
        rightChild = new TreeNode(depth);
    }
}

比较 Java 中可比较的泛型

Comparing Generics that are comparable in Java

java

generics

compare

comparable