How can I solve Exception in thread “main” java.lang.NullPointerException error

Question

Can anyone help me with the exception, given below is my code and it is giving an error:

package twoten;

import java.util.Scanner;

public class TwoTenB {

public TwoTenB() {

    double percentage;

    double a[] = null;

    double total = 0;

    double var;

    System.out.print("\tRESULT\n\n");

    Scanner scan = new Scanner(System.in);

    //double[] mark = new double[7];

    for (int i = 0; i < 7; i++) {

        System.out.print("\nMarks in subject " + (i + 1) + "\t:\t");

        var = scan.nextDouble();

        a[i] = var;

        total = total + a[i];

       //percentage = first * second * third * fourth * fifth * sixth * seventh * 100 / 700;

    }

    percentage = total * 100 / 700;

    if (a[0] > 35 && a[1] > 35 && a[2] > 35 && a[3] > 35 && a[4] > 35 && a[5] > 35 && a[6] > 35 && percentage > 35) {

        if (percentage >= 60) {

            System.out.print("\nCongratulation!!! you've got FIRST dividion\n");

        } else if (percentage >= 45 && percentage < 60) {

            System.out.print("\nCongratulation!!! you've got SECOND dividion\n");

        } else if (percentage >= 35 && percentage < 45) {

            System.out.print("\nCongratulation!!! you've got THIRD dividion\n");

        }

    } else {

        System.out.print("\nSORRY!!! you've FAILED\n");

    }

    }

}

Answer 1

Basically, the problem is:

double a[] = null;

So, it throws an exception of NullPointerException as "a" is null. So, you can try like this:

double a[] = new double[PUT_A_LENGTH_HERE]; //seems like this constant should be 7

I hope this will help.

Want to become a Java expert? join Java Certification now!!

Want to know more about Java? Watch this video on Java Tutorial for Beginners | Java Tutorial: