NullPointerException while working with Object array

Question

I am getting NullPointerException in this program. I believe there's some problem in declaring Object Array.

import java.util.Scanner;

class One 
{
    public static void main(String args[]) 
    {
        Scanner key = new Scanner(System.in);
        two[] obj = new two[3];

        for (int i = 0; i < 3; i++) {
            obj[i].roll = key.nextInt();
            obj[i].name = key.nextLine();
            obj[i].grade = key.nextLine();
        }

        for (int i = 0; i < 3; i++) {
            System.out.println(obj[i].roll + " " + obj[i].name + " " + obj[i].grade);
        }
    }
}

class Two 
{
    int roll;
    String name, grade;
}

possible duplicate of What is a Null Pointer Exception, and how do I fix it? — Raedwald
– Raedwald, Commented Nov 18, 2014 at 12:25

Eran · Accepted Answer · 2014-11-18 12:15:34Z

3

You forgot to initialize the objects in the array. Without this initialization, obj[i] contains a null reference.

two[] obj=new two[3];
for(int i=0;i<3;i++)
{
    obj[i] = new two();
    obj[i].roll=key.nextInt();
    obj[i].name=key.nextLine();
    obj[i].grade=key.nextLine();
}

answered Nov 18, 2014 at 12:15

Eran

395k57 gold badges726 silver badges793 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Bene · Accepted Answer · 2014-11-18 12:17:45Z

0

Your objects inside the array are not initialized. Call obj[i] = new Two(); as your fist statement in the first for loop. Btw: "two" must be uppercase "Two"

answered Nov 18, 2014 at 12:17

Bene

7348 silver badges20 bronze badges

Collectives™ on Stack Overflow

NullPointerException while working with Object array

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related