Binary Tree - Inorder Traversal - Using Stack (no recursion)

InorderTraversalWithStack.java

// non-recursive java program for inorder traversal

/* importing the necessary class */
import java.util.Stack;

/* Class containing left and right child of current 
node and key value*/
class Node {

    int data;
    Node left, right;

    public Node(int item) {
        data = item;
        left = right = null;
    }
}

/* Class to print the inorder traversal */
class BinaryTree {

    Node root;

    void inorder() {
        
        Stack<Node> stack = new Stack<Node>();
        Node node = root;
        while(node!=null){
            stack.push(node);
            node = node.left;
        }
        
        while(stack.size() > 0) {
            Node temp = stack.pop();
            System.out.println(" " + temp.data);
            
            if(temp.right !=null) {
                temp = temp.right;
                while(temp!=null) {
                    stack.push(temp);
                    temp = temp.left;
                }
            }
        }
    }

    public static void main(String args[]) {
        
        BinaryTree tree = new BinaryTree();
        tree.root = new Node(1);
        tree.root.left = new Node(2);
        tree.root.right = new Node(3);
        tree.root.left.left = new Node(4);
        tree.root.left.right = new Node(5);
        tree.inorder();
    }
}