java - 遍历节点类被另一个类继承的树

Question

我是初级程序员，对 Java 完全陌生。一切正常，除了我无法遍历这棵树。

public class Node extends Utility {
    protected Node left;
    protected Node right;

    public Node() {this.left = null; this.right = null;}
    public Node go_left() {return this.left;}
    public Node go_right() {return this.right;}
    public void connect_left(Node connection) {this.left = connection;}
    public void connect_right(Node connection) {this.right = connection;}
}

public class Member extends Node{
    protected String Name;
    protected int id;

    public Member() {
        this.Name = null;
        this.id = 0;
    } 

    public Member(String Name, int id){
        this.Name = Name;
        this.id = id;
    }

    public int get_member_id() {return id;}

    public String get_status() {return status;}
}

public class MemberList{
    protected Member m_root;
    public MemberList() {
        this.m_root = null;
    }

    public int validate_member_wrapper (int member_id){
        return validate_member(this.m_root, member_id);
    }

    protected int validate_member(Member root, int member_id) {
        if(root == null)
            return -1;
        if(root.get_member_id() == member_id) {
            if(root.get_status().compareToIgnoreCase("Active") == 0)
                return 1;
            else
                return 0;
        }

        if(root.get_member_id() < member_id)
            return validate_member(root.go_left(), member_id);
        else
            return validate_member(root.go_right(), member_id);

    }
}

我尝试运行此代码，但出现错误提示我无法将对象类型 Node 转换为 Member。

validate_member(root.go_left(), member_id)

和

validate_member(root.go_left(), member_id)

不允许我传入 Node 类型的对象。但是，据我了解，Member继承自Node，不允许传递Node？你如何解决这个问题？

编辑1:正如有人在评论中指出的那样，我试图通过将 Node 类中的 go_left() 和 go_right() 函数覆盖到 Member 类来解决这个问题，但不知何故它显示了一个错误，指出 Node 无法转换为 Member。

这里是变化

public class Node extends Utility {
    protected Node left;
    protected Node right;

    public Node() {this.left = null; this.right = null;}
    public Node go_left() {return this.left;}
    public Node go_right() {return this.right;}
}

public class Member extends Node{
    protected String Name;
    protected int id;

    public Member() {
        this.Name = null;
        this.id = 0;
    } 

    public Member(String Name, int id){
        this.Name = Name;
        this.id = id;
    }

    public Member go_left() {return this.left;}
    public Member go_right() {return this.right;}

    public int get_member_id() {return id;}

    public String get_status() {return status;}
}

Answer 1

because Member inherited Node, couldn't you pass Node type object into the functions since Member already inherited Node class

不，恰恰相反:您可以将 Member 传递给带有 Node 参数的方法。

这样想:您调用 root.get_member_id()，但是如果 root 只是一个 Node 而不是 成员，没有这个方法。