线索二叉树的构建

package org.lyk.main;

import java.util.Scanner;

enum NodeType
{
    child, thread;
}

class Node<T extends Comparable<T>>
{
    private static Node<String> pre = null;
    Node<T> left;
    NodeType leftType = NodeType.child;
    T data;
    Node<T> right;
    NodeType rightType = NodeType.child;

    @Override
    public String toString()
    {
        StringBuffer info = new StringBuffer();
        info.append("leftType:" + this.leftType + " ");
        if (this.leftType.equals(NodeType.child))
        {
            info.append("leftChild:" + this.left.data  + " ");
        }
        else if(this.leftType.equals(NodeType.thread))
        {
            info.append("pre data:" + this.left.data  + " ") ;
        }
        
        info.append(" data: " + this.data + " ");
        info.append("rightType:" + rightType + " ");
        
        
        if(this.rightType.equals(NodeType.child))
        {
                info.append(" rightChild:" + this.right.data  + " ");
        }
        else if(this.rightType.equals(NodeType.thread))
        {
            info.append("pre Child:" + this.right.data + " ");
        }

        return info.toString();
    }

    

    void add(T data)
    {
        if (data.compareTo(this.data) < 0)
        {
            if (null != this.left)
                this.left.add(data);
            else
            {
                this.left = new Node<T>();
                this.left.data = data;
            }
        } else
        {
            if (null != this.right)
                this.right.add(data);
            else
            {
                this.right = new Node<T>();
                this.right.data = data;
            }
        }
    }

    public static <T extends Comparable<T>> Node<T> add_first(Node<T> node, Scanner scanner)
    {
        String data = input(scanner);
        if ("*".equals(data))
        {
            node = null;
        } else
        {
            node = new Node<T>();
            node.data = (T) data;
            node.left = Node.add_first(node.left, scanner);
            node.right = Node.add_first(node.right, scanner);
        }
        return node;
    }

    private static String input(Scanner scanner)
    {
        scanner.useDelimiter("\r\n");
        System.out.print("请输入:");
        String data = (String) scanner.next();
        return data;
    }

    void get_first()
    {
        System.out.print(this.data);
        if (null != this.left)
        {
            this.left.get_first();
        }
        if (null != this.right)
        {
            this.right.get_first();
        }
    }

    public void get_middle()
    {
        if (null != this.left)
            this.left.get_middle();
        System.out.println(this);
        if (null != this.right)
            this.right.get_middle();
    }
    
    public void getMiddleDetails()
    {
        if (null != this.left && this.leftType.equals(NodeType.child))
            this.left.getMiddleDetails();
        System.out.println(this);
        if (null != this.right && this.rightType.equals(NodeType.child))
            this.right.getMiddleDetails();
    }

    public void get_last()
    {
        if (null != this.left)
            this.left.get_last();
        if (null != this.right)
            this.right.get_last();
        System.out.print(this.data);
    }

    public void setThread(Node<T> pre)
    {
        
        if (null != this.left)
        {
            this.left.setThread(this);
        }
         
        if (null == this.left)
        {
            this.leftType = NodeType.thread;
            this.left = pre;
        }
        if (null == this.right)
        {
            this.rightType = NodeType.thread;
            this.right = pre;
        } 
        
        if (null != this.right && this.rightType.equals(NodeType.child))
            this.right.setThread(this);
    }
}

class Tree<T extends Comparable<T>>
{
    Node<T> root;

    public void add_first(Scanner scanner)
    {
        this.root = Node.add_first(this.root, scanner);
    }

    public void get_first()
    {
        if (null != root)
        {
            root.get_first();
        }
    }

    public void getMiddle()
    {
        if (null != this.root)
            this.root.get_middle();
    }
    
    public void getMiddleDetails()
    {
        if (null != this.root)
            this.root.getMiddleDetails();
    }

    public void get_last()
    {
        if (null != this.root)
            this.root.get_last();
    }

    public void setThread()
    {
        if (null != this.root)
        {
            this.root.setThread(null);
        }
    }
}

public class Main
{
    public static void main(String[] args)
    {
        Scanner scanner = new Scanner(System.in);
        Tree<String> bt = new Tree<>();
        bt.add_first(scanner);
        System.out.println("add successed!!");
        bt.setThread();
        System.out.println("set successed!!!");
        System.out.println("中序输出:");
        bt.getMiddleDetails();
        System.out.println("///~ main done");
    }
}