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Problem:

I was working with Java array. Suddenly I got this error message, “exception in thread "main" java.lang.nullpointerexception”. Can somebody help me out urgently, please? I am attaching the declaring part of my code below for your better understanding.
Thanks in advance.

import java.util.Scanner;
public class TestClass {
public TestClass() {
    double percentage;
    double n[] = 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();

        n[i] = var;

        total = total + n[i];
       //percentage = first * second * third * fourth * fifth * sixth * seventh * 100 / 700;
    }

 

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Solution:

Hello Gavin, It seems you are going through some rough times with your codes. The problem was started when you declare an array n and didn’t initialize it. Think again, you have an array and it has ‘’null” value. So what is the purpose it calling in your codes? Makes sense; right?
You could have avoided the error if you declare the array this way:
double a []= new double [length_of_array]

Keep coding.

 
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