Inputted integer to char array - Java

T. Bifo :

So I recently attempted to do the HackerRank challenge that involved counting a number's holes and adding them up, and after a bit of research, I ended up making it into a char array and choosing three values to increment and add up to the sum as shown below:

 public static int countHoles(int num) {

    //create integers that count how many a number with no, one or two holes shows up
    Integer noHoles = 0;
    Integer oneHole = 0; 
    Integer twoHoles = 0; 
    Integer sum = 0;
    Integer length = 0;

    //turn the inputted number into a char array
    char [] digits = String.valueOf(num).toCharArray();
    System.out.println(digits);
    length = digits.length;

    //These nested loops incremement the numbers initialized above as the first for-each loop goes through each index value of the array
    for (int i = 0; i < digits.length; i++){
        if (digits[i]== 1 || digits[i]==2 || digits[i]==3 || digits[i]==5 || digits[i]==7){
            noHoles++;
        } else if (digits[i]==4 || digits[i]==6 || digits[i]==9 || digits[i]==0){
            oneHole+= 1;
        } else if (digits[i]==8){
            twoHoles+= 2;
        }

    }
    //add up the incremented integers. twoHoles is doubled as each unit counts as two holes and noHoles is 0 regardless of its values
    sum = oneHole + twoHoles;
    return sum;
    }
}

but the char array always return as a normal integer! I can't try the modulus approach since 0 is used (has one hole in it), and a bunch of variants on String.valueOf(num).toCharArray() such as ("" + num).toCharArray() and Integer.toString(number).toCharArray(), but it stills outputs the inputted number instead of the wanted char array. Of course, the rest of the method spits out 0 because of the empty array too.

I'm a bit of a newbie, but damn is this frustrating. I feel like it's a micro-detail I haven't seen or don't know instead of my logic. Any help please?

Jacob G. :

You're comparing a char to an int with the incorrect int values (for example, '1' != 1). It would safer to compare char to char:

if (digits[i] == '1' || digits[i] == '2' || digits[i] == '3' || digits[i] == '5' || digits[i] == '7') {
    noHoles++;
} else if (digits[i] == '4' || digits[i] == '6' || digits[i] == '9' || digits[i] == '0') {
    oneHole += 1;
} else if (digits[i] == '8') {
    twoHoles += 2;
}

You also don't need the noHoles variable, as it goes unused after it's incremented. If you remove noHoles, you can also remove the first if-statement where you check if the number is 1, 2, etc.

Also to print your char[], use Arrays#toString:

System.out.println(Arrays.toString(digits));