Java Program to Perform the postorder tree traversal

In this example, we will learn to perform the postorder tree traversal in Java.

To understand this example, you should have the knowledge of the following Java programming topics:

Example: Java Program to perform postorder tree traversal

class Node {
  int item;
  Node left, right;

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

class Tree {
  // Root of Binary Tree
  Node root;

  Tree() {
  root = null;
  }

  void postorder(Node node) {
    if (node == null)
      return;

    // traverse the left child
    postorder(node.left);

    // traverse the right child
    postorder(node.right);

    // traverse the root node
    System.out.print(node.item + "->");
  }

  public static void main(String[] args) {

    // create an object of Tree
    Tree tree = new Tree();

    // create nodes of the tree
    tree.root = new Node(1);
    tree.root.left = new Node(12);
    tree.root.right = new Node(9);

    // child nodes of left child
    tree.root.left.left = new Node(5);
    tree.root.left.right = new Node(6);

    // postorder tree traversal
    System.out.println("Postorder traversal");
    tree.postorder(tree.root);
  }
}