Texas Hold 'em recognizing one pair

Question

I'm having trouble with my program recognizing a one pair ONLY AFTER it first checks for a two pair. When checking for the one pair first it finds it ok. But when I check for the two pair first then check for a one pair it doesn't find it. Any help would be appreciated.

package card.game.simulator;

import java.util.ArrayList;

public class RankingUtility {
private RankingEnum rank;

public String getRankOfHand(ArrayList<Card> hand) {
    System.out.printf("%s\n", hand.toString());
    ArrayList<Card> rankingCards = getTwoPair(hand);
    if(rankingCards != null) {
        return "Two Pair!";
    }
    System.out.printf("%s\n", hand.toString());
    rankingCards = getOnePair(hand);
    if(rankingCards != null) {
        return "One Pair!";
    }
    System.out.printf("%s\n", hand.toString());
    return "You got nuthin...";
}

public boolean isSameSuit(ArrayList<Card> hand) {
    CardSuitEnum suit = hand.get(0).getSuit();
    for(Card card : hand) {
        if(card.getSuit() != suit) {
            return false;
        }
    }
    return true;
}

public ArrayList<Card> checkPair(ArrayList<Card> hand) {
    ArrayList<Card> checkedPair = new ArrayList<>();
    for(Card card1 : hand) {
        checkedPair.add(card1);
        for(Card card2 : hand) {
            if(!card1.equals(card2) && card1.getFace().equals(card2.getFace())) {
                checkedPair.add(card2);
                return checkedPair;
            }
        }
        checkedPair.clear();
    }
    return null;
}

public ArrayList<Card> getTwoPair(ArrayList<Card> hand) {
    ArrayList<Card> twoPair = new ArrayList<>();
    ArrayList<Card> checkedPair = checkPair(hand);
    if(checkedPair != null) {
        twoPair.addAll(checkedPair);
        hand.removeAll(checkedPair);
    }
    checkedPair = checkPair(hand);
    if(checkedPair != null) {
        twoPair.addAll(checkedPair);
        return twoPair;
    }
    return null;
}

public ArrayList<Card> getOnePair(ArrayList<Card> hand) {
    return checkPair(hand);
}
}

I would suggest adding a method to RankingEnum like: public boolean isRank(Set cards); That way each ranking is responsible for determining if a hand qualifies instead. — HiJon89, Jan 21 '13 at 21:47

score 5 · Answer 1 · edited Jan 21 '13 at 21:31

5

In checkTwoPair you are doing hand.removeAll(). This is removing it from the underlying ArrayList. This is why you are not finding it afterwards.

edited Jan 21 '13 at 21:31

Jeff

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answered Jan 21 '13 at 21:29

Elliott Hill

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score 3 · Answer 2 · answered Jan 21 '13 at 21:29

The problem is that you're modifying hand when looking for two pair:

   hand.removeAll(checkedPair);

Thus when getTwoPair() completes, the sole pair has been removed from the hand, and checkPair() no longer works.

You need to make getTwoPair() non-intrusive.

Alternatively, you could combine the two methods into one, returning zero, two or four cards depending on how many pairs have been found.

score 0 · Accepted Answer · answered Jan 21 '13 at 21:30

When you run getTwoPair the first operation you do is checkPair(hand); This finds the pair (the one you want) removes it, then tries to check again. When this check fails, it returns.

After the return you're left with (1) a hand that has the pair removed and (2) a null return from getTwoPair. This result leaves you with a condition that causes the main flow to continue, yet fail on finding the single pair, since it was removed.

I suggest making a copy of the array list to search on. If you fail to find two pairs, simply return the original array. If you find tow pairs, return the modified array.

Texas Hold 'em recognizing one pair

3 Answers3