Whats wrong with this specified code in this java code?

Question

class Pointgrejen{
    public static void main (String [] args){
        int[] a = new int[5];
        a[3] = 7;

        Point[] b = new Point[5];
        b[3].x = 7; 

        System.out.print(a[3]);
        System.out.print(b[3]);
    }
}

Why isn't the program executing? Point is a java class in java, but is the error in this code that I havent defined what type of data the array should hold in the point array? Or whats the bigger issue with this code?

`new Point[5]` doesn't create 5 points. It creates an array of nulls that you can store instances of `Point` in. — Andy Turner, May 11 '20 at 08:06

score 1 · Answer 1 · answered May 11 '20 at 07:58

1

You created the array, so the array values will be null by default.

Means b[3] will be null, so you will get NullPointerException in below line of code:

Point[] b = new Point[5];
b[3].x = 7;

So to fix it create objects and assign them to array:

b[3] = new Point();
b[3].x = 7

answered May 11 '20 at 07:58

Chaitanya

15,403
35
96
137

So problem is that i need to first create b[3] to be an object? – Mr Miyagi May 11 '20 at 08:12
@MrMiyagi yes, create and use it – Chaitanya May 11 '20 at 12:21

score 0 · Answer 2 · answered May 11 '20 at 08:00

0

You created the points array, but is filled with nulls so to assign b[3].x = 7; you must first do b[3] = new Point();

answered May 11 '20 at 08:00

Gabriel Guerrero

466
4
5

So i have to make b[3] and object first basically – Mr Miyagi May 11 '20 at 08:12

Whats wrong with this specified code in this java code?

2 Answers2