Finding the best category of poker hand

Question

I have 16 methods in Java that return int values. I need to find the one that returns the highest value.

I initially implemented this:

private int best() {
    int max = playGame(ONES);
    max = Math.max(max, playGame(TWOS));
    max = Math.max(max, playGame(THREES));
    max = Math.max(max, playGame(FOURS));
    max = Math.max(max, playGame(FIVES));
    max = Math.max(max, playGame(SIXES));
    max = Math.max(max, playGame(SEVENS));
    max = Math.max(max, playGame(EIGHTS));
    max = Math.max(max, playGame(THREE_OF_A_KIND));
    max = Math.max(max, playGame(FOUR_OF_A_KIND));
    max = Math.max(max, playGame(FULL_HOUSE));
    max = Math.max(max, playGame(SMALL_STRAIGHT));
    max = Math.max(max, playGame(LARGE_STRAIGHT));
    max = Math.max(max, playGame(ALL_DIFFERENT));
    max = Math.max(max, playGame(CHANCE));
    max = Math.max(max, playGame(ALL_SAME));
    return max;
}

To make this slightly better, I could reduce one comparison by comparing two methods simultaneously.

private int best() {
    int max1 = Math.max(playGame(ONES), playGame(TWOS));
    int max2 = Math.max(playGame(THREES), playGame(FOURS));
    int max3 = Math.max(playGame(FIVES), playGame(SIXES));
    int max4 = Math.max(playGame(SEVENS), playGame(EIGHTS));
    int max5 = Math.max(playGame(THREE_OF_A_KIND), playGame(FOUR_OF_A_KIND));
    int max6 = Math.max(playGame(FULL_HOUSE), playGame(SMALL_STRAIGHT));
    int max7 = Math.max(playGame(LARGE_STRAIGHT), playGame(ALL_DIFFERENT));
    int max8 = Math.max(playGame(CHANCE), playGame(ALL_SAME));
    int max11 = Math.max(max1, max2);
    int max12 = Math.max(max3, max4);
    int max13 = Math.max(max5, max6);
    int max14 = Math.max(max7, max8);
    int max21 = Math.max(max11, max12);
    int max22 = Math.max(max13, max14);
    int max = Math.max(max21, max22);
    return max;
}

I mentioned 16 methods as playGame(CONSTANT) callbacks different methods based on the constant. However, this code is still bad. What could be a better way to achieve this?

Answer 1

I think that it would be best if you could put those constants into a enum so that you can use Enum.values to get them all in an array. If so you can do this:

enum Play {
 TWOS, THREES, FOURS, FIVES, SIXES, SEVENS, EIGHTS, THREE_OF_A_KIND, 
 FOUR_OF_A_KIND, FULL_HOUSE, SMALL_STRAIGHT, LARGE_STRAIGHT, ALL_DIFFERENT,
 CHANCE, ALL_SAME; 
}

class Main {

  int playGame(Play play) { 
     // you need to implement this method returning something meaningful.
     return 0; 
  }

  int best() {
     return Stream.of(Play.values())
                  .mapToInt(this::playGame)
                  .max().getAsInt();
  }
}

If you want to keep those constants as independent static final (Strings?) then you will need to create a list of them explicitly:

//...
static final String TWOS = "TWOS";
static final String THREES = "THREES";
//...
static final List<String> PLAYS = Arrays.asList(TWOS, THREES, ...);
//...
int best() {
   return PLAYS.stream()
               .mapToInt(this::playGame)
               .max().getAsInt();
}