Covering all scenarios with if statement

Question

I'm doing the below homework exercise:

Given 2 int values greater than 0, return whichever value is nearest to 21 without going over. Return 0 if they both go over.

I've made the below code:

public static void main(String[] args) {
    System.out.println(blackjack(22,22));
    System.out.println(blackjack(25,25));
    System.out.println(blackjack(19,25));
    System.out.println(blackjack(25,19));
    System.out.println(blackjack(10,10));
    System.out.println(blackjack(19,10));
    System.out.println(blackjack(1,19));
}

// Create a method like:
public static int blackjack(int a, int b) {
    if (a > 21 && b > 21) {
        return 0;
    }
    else if (a <= 21 || b > 21) {
        return a;
    }
    else if (a > 21 || b <= 21) {
        return b;
    }
    else if (a >= b) {
        return a;
    }
    else {
        return b;
    }
}

All of it works except the last line of output in my main. I keep getting "a" or, "1" in this case, so I'm not sure what is wrong with my last line in my method declaration. I have a feeling something is wrong but I'm not sure what to change.

Answer 1

You could also avoid some of those if-statements if you instead rely on some mathematical operations:

private static final int TARGET = 21;
public static void main (String[] args) throws java.lang.Exception {
    System.out.println(blackjack(22,22)); //  0
    System.out.println(blackjack(25,25)); //  0
    System.out.println(blackjack(19,25)); // 19
    System.out.println(blackjack(25,19)); // 19
    System.out.println(blackjack(10,10)); // 10
    System.out.println(blackjack(19,10)); // 19
    System.out.println(blackjack(1,19));  // 19
}

public static int blackjack(int a, int b) {
    if ( a > TARGET && b > TARGET) {
        return 0;
    }

    return Math.abs(a - TARGET) < Math.abs(b - TARGET) 
       ? a 
       : b;
}

Note: This works here because 21 is nowhere close to the MAX_INT boundary; if it were overflow would be an issue. Here this article, subtraction is not comparison, for more information if you're interested.

Working example on Ideone