programming-examples/java/Graph_Problems_Algorithms/Java Program to Perform Search in a BST.java

//This is a java program to search an element in a Binary Search Tree
import java.util.Random;
import java.util.Scanner;

class BSTNode
{
    BSTNode left, right;
    int     data;

    public BSTNode()
    {
        left = null;
        right = null;
        data = 0;
    }

    public BSTNode(int n)
    {
        left = null;
        right = null;
        data = n;
    }

    public void setLeft(BSTNode n)
    {
        left = n;
    }

    public void setRight(BSTNode n)
    {
        right = n;
    }

    public BSTNode getLeft()
    {
        return left;
    }

    public BSTNode getRight()
    {
        return right;
    }

    public void setData(int d)
    {
        data = d;
    }

    public int getData()
    {
        return data;
    }
}

class BSTree
{
    private BSTNode root;

    public BSTree()
    {
        root = null;
    }

    public boolean isEmpty()
    {
        return root == null;
    }

    public void insert(int data)
    {
        root = insert(root, data);
    }

    private BSTNode insert(BSTNode node, int data)
    {
        if (node == null)
            node = new BSTNode(data);
        else
            {
                if (data <= node.getData())
                    node.left = insert(node.left, data);
                else
                    node.right = insert(node.right, data);
            }
        return node;
    }

    public boolean search(int val)
    {
        return search(root, val);
    }

    private boolean search(BSTNode r, int val)
    {
        boolean found = false;
        while ((r != null) && !found)
            {
                int rval = r.getData();
                if (val < rval)
                    r = r.getLeft();
                else if (val > rval)
                    r = r.getRight();
                else
                    {
                        found = true;
                        break;
                    }
                found = search(r, val);
            }
        return found;
    }

    public void inorder()
    {
        inorder(root);
    }

    private void inorder(BSTNode r)
    {
        if (r != null)
            {
                inorder(r.getLeft());
                System.out.print(r.getData() + " ");
                inorder(r.getRight());
            }
    }

    public void preorder()
    {
        preorder(root);
    }

    private void preorder(BSTNode r)
    {
        if (r != null)
            {
                System.out.print(r.getData() + " ");
                preorder(r.getLeft());
                preorder(r.getRight());
            }
    }

    public void postorder()
    {
        postorder(root);
    }

    private void postorder(BSTNode r)
    {
        if (r != null)
            {
                postorder(r.getLeft());
                postorder(r.getRight());
                System.out.print(r.getData() + " ");
            }
    }
}

public class Searching_Tree
{
    public static void main(String[] args)
    {
        BSTree bst = new BSTree();
        System.out.println("Binary Search Tree Deletion Test\n");
        Scanner input = new Scanner(System.in);
        Random rand = new Random();
        int elements = 15;
        for (int i = 0; i < elements; i++)
            bst.insert(Math.abs(rand.nextInt(100)));
        System.out.println("Enter integer element to search");
        System.out.println("Search result : " + bst.search(input.nextInt()));
        System.out.print("\nPost order : ");
        bst.postorder();
        System.out.print("\nPre order  : ");
        bst.preorder();
        System.out.print("\nIn order   : ");
        bst.inorder();
        input.close();
    }
}

/*
Binary Search Tree Searching Test

Enter integer element to search
15
Search result : true

Post order : 0 10 5 24 15 38 4 63 55 72 67 79 97 80 49
Pre order  : 49 4 0 38 15 5 10 24 80 79 67 55 63 72 97
In order   : 0 4 5 10 15 24 38 49 55 63 67 72 79 80 97