java - 用Java实现二叉搜索树

Question

这是我为二叉搜索树编写的代码。不幸的是，当我运行它时，它没有给出所需的输出。有人可以告诉我我做错了什么吗？

import java.util.ArrayList;


public class BinaryOrderedTree {
    BinaryOrderedTree left;
    BinaryOrderedTree right;
    static BinaryOrderedTree top;
    int key;
    static ArrayList<BinaryOrderedTree> values=new ArrayList<BinaryOrderedTree>();



    public int getKey(){
        return key;
    }


    public void setTop(BinaryOrderedTree top1){
        top=top1;
    }

    public BinaryOrderedTree getLeft(){
        return this.left;
    }

    public BinaryOrderedTree getRight(){
        return this.right;
    }

    public BinaryOrderedTree(int key){
        this.key=key;
    }

    public static BinaryOrderedTree addNode(BinaryOrderedTree node,BinaryOrderedTree top){
        if (node.getKey()<top.getKey()){
            if(top.left==null){
                System.out.println(node.getKey());
                System.out.println("left");
            top.left=node;
            }
            else{
                addNode(node,top.left);
            }
        }
        if(node.getKey()>top.getKey()){
            if(top.right==null){
                System.out.println(node.getKey());
                System.out.println("right");
                top.right=node;
            }
            else{
                addNode(node,top.right);
            }
        }
        return node;
    }

    public static BinaryOrderedTree searchNode(BinaryOrderedTree search, 
            BinaryOrderedTree top){
        if(search.getKey()==top.getKey()){
            return top;
        }
        else if(search.getKey()<top.getKey()){
            return searchNode(search,top.left);
        }
        else if(search.getKey()>top.getKey()){
            return searchNode(search,top.right);
        }
        return null;
    }

    public static BinaryOrderedTree traverse(BinaryOrderedTree top){
        values.add(top);
        System.out.println(top.getKey());
        if(top.left !=null)
        traverse(top.left);
        else if (top.right!=null)
        traverse(top.right);
        values.add(top.left);
        values.add(top.right);
        return top;
    }   

    public static void main(String[] args){
        BinaryOrderedTree top=new BinaryOrderedTree(7);
        BinaryOrderedTree firstNode=new BinaryOrderedTree(6);

        BinaryOrderedTree.addNode(firstNode,top);
        BinaryOrderedTree secondNode=new BinaryOrderedTree(4);
        BinaryOrderedTree.addNode(secondNode, top);
        BinaryOrderedTree thirdNode=new BinaryOrderedTree(8);
        BinaryOrderedTree.addNode(thirdNode, top);
        BinaryOrderedTree fourthNode=new BinaryOrderedTree(3);
        BinaryOrderedTree.addNode(fourthNode, top);
        BinaryOrderedTree.traverse(top);
//      System.out.println(BinaryOrderedTree.values);
    }
}

This is the output I get

    6
left
4
left
8
right
3
left
traversing pre-order
7
6
4
3

我只能假设节点已正确添加。但它无法显示顶部节点右侧的节点，仅遍历左侧部分。有人可以指出这个缺陷吗？

Answer 1

删除右侧遍历中的else:

if(top.left !=null)
    traverse(top.left);
if (top.right!=null)
    traverse(top.right);

<小时/>

顺便说一句，您的值也可能会被奇怪地填充。 values.add(top) 就足够了。删除那些 values.add(top.left) 和 values.add(top.right)。

<小时/>

顺便说一句(还有一个)variable shadowing并不能真正帮助理解你的代码。