Java Data Structures Tutorial

Inserting a key into a tree

There is no particular rule to insert elements in to a binary tree you can insert nodes where ever you need.

The only point you should keep in mind while inserting nodes is that in a binary tree every node can have only two children at max.

Therefore, to insert a node into a tree,

Traverse through each node level by level check whether it has left node and right node.
If any node have both left and right nodes you cannot insert another node because a node in a binary tree can have only two child nodes at max, add these values to the queue and move on.
If any node doesn’t have left node or right node then create a new node and add it there.

In short, insert node to a parent which has no left sub tree or, right sub tree or, both.

Example

Live Demo

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

class Node{
   int data;
   Node leftNode, rightNode;
   
   Node() {
      leftNode = null;
      rightNode = null;     
      this.data = data;
   }
   Node(int data) {
      leftNode = null;
      rightNode = null;     
      this.data = data;
   }   
   int getData() {
      return this.data;	   
   }
   Node getleftNode() {
      return this.leftNode;	   
   }	   
   Node getRightNode() {
      return this.leftNode;	   
   }
   void setData(int data) {
      this.data = data; 
   }		   
   void setleftNode(Node leftNode) {
      this.leftNode = leftNode;	   
   }
   void setRightNode(Node rightNode) {
      this.leftNode = rightNode;	      
   }
}
public class InsertingElements {
   public static int[] insertElement(int[] myArray, int pos, int data) {
      int j = myArray.length;      
      int lastElement = myArray[j-1];      
	      
      for(int i = (j-2); i >= (pos-1); i--) {
         myArray[i+1] = myArray[i];
      }     
      myArray[pos-1] = data;
      
      int[] resultArray = new int[j+1];      
      for(int i = 0; i < myArray.length; i++) {
         resultArray[i] = myArray[i]; 
      }   
      resultArray[resultArray.length-1] = lastElement;
      return resultArray;
	}
	public static void main(String args[]){
      int[] myArray = {10, 20, 30, 45, 96, 66};      
      int pos = 3;
      int data = 10005;
      int[] result = insertElement(myArray, pos, data);   
      
      for(int i = 0; i < result.length; i++){
         System.out.println(result[i]);
      }   
   }
}

Output