用java实现的二叉排序树

public class Node {

    public int value;
    public Node left;
    public Node right;
    
    public void store(int value){
        if(value<this.value){
            if(this.left == null){
                this.left = new Node();
                this.left.value = value;
            }else{
                this.left.store(value);
            }
        }else if(value>this.value){
            if(this.right == null){
                this.right = new Node();
                this.right.value = value;
            }else{
                this.right.store(value);
            }
        }
    }
    
    public boolean find(int value){
        System.out.println("happen"+this.value);
        if(value == this.value){
            return true;
        }else if(value<this.value){
            return this.left.find(value);
        }else{
            return this.right.find(value);
        }
    }
    
    public void preList(){
        System.out.println(this.value+",");
        if(left!=null){
            this.left.preList();
        }
        if(this.right != null){
            this.right.preList();
        }
    }
    
    public void middleList(){
        if(this.left != null){
            left.middleList();
        }
        System.out.println(this.value + ",");
        if(this.right != null){
            right.middleList();
        }
    }
    
    public void afterList(){
        if(this.left != null){
            this.left.afterList();
        }
        if(this.right != null){
            right.afterList();
        }
        System.out.println(value + ",");
    }
    
    public static void main(String []args){
        int [] data = new int[20];
        for(int i=0;i<data.length;i++){
            data[i] = (int)(Math.random()*100)+1;
            System.out.println(data[i]+",");
        }
        
        System.out.println();
        
        Node root = new Node();
        root.value = data[0];
        for(int i=1;i<data.length;i++){
            root.store(data[i]);
        }
        
        root.find(data[19]);
        
        root.preList();
        System.out.println();
        root.middleList();
        System.out.println();
        root.afterList();
    }
}