tree_traversals.java

class tree_traversals {
  
  class Node {
  int item;
  Node left, right;

  public Node(int key) {
  item = key;
  left = right = null;
  }
}
  // Root of Binary Tree
  Node root;

  tree_traversals() {
  root = null;
  }

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

  // Traverse left
  postorder(node.left);
  // Traverse right
  postorder(node.right);
  // Traverse root
  System.out.print(node.item + "->");
  }

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

  // Traverse left
  inorder(node.left);
  // Traverse root
  System.out.print(node.item + "->");
  // Traverse right
  inorder(node.right);
  }

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

  // Traverse root
  System.out.print(node.item + "->");
  // Traverse left
  preorder(node.left);
  // Traverse right
  preorder(node.right);
  }

  public static void main(String[] args) {
  tree_traversals tree = new tree_traversals();
  tree.root = new Node(1);
  tree.root.left = new Node(12);
  tree.root.right = new Node(9);
  tree.root.left.left = new Node(5);
  tree.root.left.right = new Node(6);

  System.out.println("\n\nInorder traversal");
  tree.inorder(tree.root);

  System.out.println("\n\nPreorder traversal ");
  tree.preorder(tree.root);

  System.out.println("\n\nPostorder traversal");
  tree.postorder(tree.root);
  }
}