Binary Tree Preorder Traversal in Java

Binary Tree Preorder Traversal in Java

1. Recursive Preorder traversal of Binary tree.
2. Iterative Preorder traversal of Binary tree.

1. Visit the root node and print data of that node. 
2. Traverse the Left subtree.
3. Traverse the Right subtree. 

Preorder traversal of binary tree example

Preorder Traversals Java Program.

package javabypatel.tree;

public class Node {
 private int data;
 private Node left;
 private Node right;

 public Node(int data) {
  this.data=data;
 }

 public int getData() {
  return data;
 }
 public void setData(int data) {
  this.data = data;
 }
 public Node getLeft() {
  return left;
 }
 public void setLeft(Node left) {
  this.left = left;
 }
 public Node getRight() {
  return right;
 }
 public void setRight(Node right) {
  this.right = right;
 }
}

package javabypatel.tree;

import java.util.LinkedList;
import java.util.Queue;

public class PreorderBinaryTreeTraversal {
 private Node rootNode;

 public static void main(String[] args) {
  new BinaryTreeTraversal();
 }

 public PreorderBinaryTreeTraversal(){

  addNode(rootNode, 45); 
  addNode(rootNode, 25); 
  addNode(rootNode, 75); 
  addNode(rootNode, 15); 
  addNode(rootNode, 35); 
    
  System.out.println("\nPre Order Traversal :");
  printTreePreOrder(rootNode);
 }
  
 //Preorder traversal printing. 
 private void printTreePreOrder(Node rootNode){
  if(rootNode==null)
   return;
  System.out.print(rootNode.getData() + " ");
  printTreePreOrder(rootNode.getLeft());
  printTreePreOrder(rootNode.getRight());
 }
  
 private void addNode(Node rootNode, int data){
  if(rootNode==null){
   Node temp1 = new Node(data);
   this.rootNode=temp1;
  }else{
   addNodeInProperPlace(rootNode, data);
  }
 }
 
 private void addNodeInProperPlace(Node rootNode, int data){ 
  if(data>rootNode.getData()){
   if(rootNode.getRight()!=null){
    addNode(rootNode.getRight(), data);
   }else{
    Node temp1 = new Node(data);
    rootNode.setRight(temp1);
   }
  }else if(data<rootNode.getData()){
   if(rootNode.getLeft()!=null){
    addNode(rootNode.getLeft(), data);
   }else{
    Node temp1 = new Node(data);
    rootNode.setLeft(temp1);
   }
  }
 }
}

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Postorder Traversal Java Program

Level order traversal in binary tree

Zig Zag Traversal of Binary Tree. 

Boundary Traversal of binary tree. 

Print Nodes in Top View of Binary Tree

Print Nodes in Bottom View of Binary Tree.

Print a Binary Tree in Vertical Order