# How to binary search in Java

Sun Dec 29 2019 20:06:50 GMT+0000 (UTC)

Posted by
@frogblog
#java
#interviewquestions
#search

import java.util.Stack;
/**
* Java Program to implement a binary search tree. A binary search tree is a
* sorted binary tree, where value of a node is greater than or equal to its
* left the child and less than or equal to its right child.
*
* @author WINDOWS 8
*
*/
public class BST {
private static class Node {
private int data;
private Node left, right;
public Node(int value) {
data = value;
left = right = null;
}
}
private Node root;
public BST() {
root = null;
}
public Node getRoot() {
return root;
}
/**
* Java function to check if binary tree is empty or not
* Time Complexity of this solution is constant O(1) for
* best, average and worst case.
*
* @return true if binary search tree is empty
*/
public boolean isEmpty() {
return null == root;
}
/**
* Java function to return number of nodes in this binary search tree.
* Time complexity of this method is O(n)
* @return size of this binary search tree
*/
public int size() {
Node current = root;
int size = 0;
Stack<Node> stack = new Stack<Node>();
while (!stack.isEmpty() || current != null) {
if (current != null) {
stack.push(current);
current = current.left;
} else {
size++;
current = stack.pop();
current = current.right;
}
}
return size;
}
/**
* Java function to clear the binary search tree.
* Time complexity of this method is O(1)
*/
public void clear() {
root = null;
}
}

*content_copy* Copy
Copied from tutorial:
"It's just a structure, we will subsequently add methods to add a node in a binary search tree, delete a node from binary search tree and find a node from BST in the subsequent part of this binary search tree tutorial.
In this implementation, I have created a Node class. It has a data element, an integer and a Node reference to point to another node in the binary tree.
I have also created four basic functions, as shown below:
getRoot(), returns the root of binary tree
isEmpty(), to check if binary search tree is empty or not
size(), to find the total number of nodes in a BST
clear(), to clear the BST"

https://javarevisited.blogspot.com/2015/10/how-to-implement-binary-search-tree-in-java-example.html#axzz4wnEtnNB3
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