Why is this program giving “division by zero” error?

Give one point to A[i] if either A[i]%A[j] ==0 or A[j]%A[i] == 0 Calculating the total points received by every element. Input: A={2,3,4,5,6} Output: 2,1,1,0,2 I am getting this error message: Exception in thread “main” java.lang.ArithmeticException: / by zero

at Main.main(Main.java:29)

 class Main {

    public static void main(String args[])
    {
        ArrayList<Integer> al
            = new ArrayList<>();

        al.add(2);
        al.add(3);
        al.add(4);
        al.add(5);
        al.add(6);
        
        int c=al.size()-1;
        
        while(c>=0){
        int count=0;
        for (int i=0; i<al.size(); i++){
            if(i==c){
                break;
            }
            else{
                if(al.get(c)>al.get(i)){
                    if(al.get(c)%al.get(i) == 0){
                        count++;
                    }
                }
                else{
                    if(al.get(i)%al.get(c) == 0){
                        count++;
                    }
                }
            }
        }
        al.set(1,count);
        --c;
        }
        for(int i : al){
            System.out.print(i);
        }
    }
}

Answer

When you are running the code, this line:

al.set(1,count);

Can set count = 0. So when the value at slot 1 will be used, it will throw the error.

For “where is the error”, java has pretty error informations, and it will return something like:

Exception in thread "main" java.lang.ArithmeticException: / by zero
    at com.me.myprogram.MainClass.main(MainClass.java:61)

And you will see that the line 61 is:

if(al.get(c) % al.get(i) == 0){

I suggest you to check when it’s 0, or to don’t set 0 count like check if it’s 0, and set 1, for example:

if(count != 0) {
   al.set(1, count); // here the value will change only if we could use it after
} /* With this part, it will change the value but also preventing all issue with /0
 else {
   al.set(1, 1);
}
*/