Find Diameter Of Binary Tree

package tree;
 
import java.util.LinkedList;
import java.util.Queue;

public class FindDiameterOfBinaryTree {
 
 private Node rootNode;
 private static int maxDiameterTillNow;

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

 public FindDiameterOfBinaryTree(){
  addNode(rootNode, 100);
  addNode(rootNode, 90);
  addNode(rootNode, 150);
  addNode(rootNode, 80);
  addNode(rootNode, 91);
  addNode(rootNode, 200);
  addNode(rootNode, 70);
  addNode(rootNode, 85);
  addNode(rootNode, 93);
  addNode(rootNode, 83);
  addNode(rootNode, 92);
  addNode(rootNode, 94);
  addNode(rootNode, 81);
  addNode(rootNode, 84);
  addNode(rootNode, 95);

  printTreeLevelOrder(rootNode);
  System.out.println();
  printDiameter(rootNode);
  System.out.println(maxDiameterTillNow-1);
 }

 private int printDiameter(Node startNode) {
  return calculateDiameter(startNode);
 }

 private int calculateDiameter(Node startNode){
  if(startNode==null)
   return 0;

  int left = 1 + calculateDiameter(startNode.getLeft());
  int right = 1 + calculateDiameter(startNode.getRight());

  if(left + right >maxDiameterTillNow){
   maxDiameterTillNow = left + right;
  }
  if(left>right)
   return left;
  else
   return right;

 }

 private void printTreeLevelOrder(Node rootNode){
  if(rootNode==null)
   return;
  Queue<Node> queue = new LinkedList<Node>();
  queue.add(rootNode);

  while(!queue.isEmpty()){
   Node obj = (Node)queue.poll();
   System.out.print(obj.getData() + " ");
   if(obj.getLeft()!=null)
    queue.add(obj.getLeft());

   if(obj.getRight()!=null)
    queue.add(obj.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);
    }
  }
 }
 
}

package tree;

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

 public int getData() {
  return data;
 }

 public void setData(int data) {
  this.data = data;
 }
}