Why do I get an ArrayIndexOutOfBoundsException in this prime number check?

Question

I was finding out highest prime factor which divides num, as shown in program, there\'s a issue with array and

arr[j] = i;
j++;

Excepti         


        

Answer 1

Arrays in java are not lists: once allocated, your array won't grow magically.

You created the array with: int arr[] = {j}; thus the array has one cell only.

You should initialise your array with at least num/2 cells, with something like int arr[] = new int[num/2]; arr[0] = j;