Depth First Search of a binary tree - Java implementation

DepthFirstSearch.java

package megha.codingproblem.trees;

import java.util.Stack;

/**
 * Git repo link - https://github.com/meghakrishnamurthy/CodingProblems/blob/master/src/megha/codingproblem/trees/DepthFirstSearch.java
 * 
 * Depth first search implementation using a Stack
 * 
 * Time complexity - O(n)
 * Space complexity - Best/Average case O(1) and worst case O(n)
 * @author megha krishnamurthy
 *
 */
public class DepthFirstSearch {

	/**
	 * This method performs a depth first search on a binary tree
	 * @param root
	 */
	public void depthFirstSearch(Node root) {
		if(root == null) {
			return;
		}
		
		Stack<Node> nodeStack = new Stack<Node>();
		nodeStack.push(root);
		
		while(!nodeStack.isEmpty()) {
			Node node = nodeStack.pop();
			System.out.print(node.data + " ");
			
			if(node.right != null) {
				nodeStack.push(node.right);
			}
			if(node.left != null) {
				nodeStack.push(node.left);
			}
		}
	}
	
	public static void main(String args[]) {
		Node root = new Node(10);
		root.left = new Node(6);
		root.right = new Node(21);
		root.left.left = new Node(1);
		root.left.right = new Node(8);
		root.right.left = new Node(13);
		root.right.right = new Node(25);
		root.right.left.left = new Node (12);
		root.right.left.right = new Node(18);
		
		DepthFirstSearch dfs = new DepthFirstSearch();
		dfs.depthFirstSearch(root);
	}
}

private class Node {
	int data;
	Node left;
	Node right;
	
	private Node(int value) {
		data = value;
		left = right = null;
	}
}