Doubt related binary tree

#1

In construction of binary tree it is giving null pointer Exception. how to solve it?

#2

share your complete code here

#3

package generictree; import java.util.Scanner; public class binarytree { class Node { int data; Node left; Node right; Node(int data,Node left,Node right) { this.data=data; this.left=left; this.right=right; } } private Node root=null; private int size=0; binarytree() { Scanner s = new Scanner(System.in); Node root = takeinput(s,null,false); } private Node takeinput(Scanner s,Node parent,boolean isleftorright ) {if(parent==null) { System.out.println(“enter the data for root node”); }else { if(isleftorright) { System.out.println(“enter the data for left child”+parent.data); } else { System.out.println(“enter the data for right child”+parent.data); } } int nodedata=s.nextInt(); Node node =new Node(nodedata,null,null); this.size++; boolean choice=false; System.out.println(“do you have left child of”+node.data); choice=s.nextBoolean(); if(choice) { node.left=takeinput(s,node,true); } choice = false; System.out.println(“do you have right child of”+node.data); choice=s.nextBoolean(); if(choice) { node.right=takeinput(s,node,false); } return node; } public void display() { this.display(this.root); } private void display(Node node) { String str=""; if(node.left!=null) { str=str+node.left.data+"=>"; } else { str=str+“END=>”; } str=str+node.data; if(node.right!=null) { str=str+"<="+node.right.data; } else { str=str+"<=END"; } System.out.println(str); if(node.left!=null) { this.display(node.left); } if(node.right!=null) { this.display(node.right); } } }

#4

save your code on ide.codingblocks.com as it is very hard to difficult this above unformatted code

#5
#6

I have saved the code on ide

#7
#8

in line no 21 of your first link dont write Node root=takeInput(…)(it is creating local variable root)
just write root=takeInput(…)…

#9

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