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?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — Raedwald, Nov 18 '14 at 12:25

score 3 · Accepted Answer · answered Nov 18 '14 at 12:15

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();
}

score 0 · Answer 2 · answered Nov 18 '14 at 12:17

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 '14 at 12:17

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NullPointerException while working with Object array

2 Answers2