Custom sorting for ArrayList

Question

I'd like to sort an ArrayList according to my logic:

        ArrayList<String> cards = new ArrayList<>(Arrays.asList("K","A","7","Q","6","J","T"));
// desired result: [6, 7, T, J, Q, K, A]

So like poker card this is the ascending order: 2,3,4,5,6,7,8,9,T,J,Q,K,A

How could I achieve it?

Hint: don't use strings. You can create your own type to encapsulate this information. — Makoto, Oct 14 '18 at 04:14
Please see https://stackoverflow.com/questions/5245093/using-comparator-to-make-custom-sort — Sualeh Fatehi, Oct 14 '18 at 04:23

score 1 · Accepted Answer · answered Oct 14 '18 at 04:47

Please try if this code helps you.

import java.util.*;

class CustomComparator implements Comparator<String> {
    final String ORDER= "23456789TJQKA";
    public int compare(String a, String b) {
        return ORDER.indexOf(a) -  ORDER.indexOf(b) ;
    }
}

public class SortIt {

    public static void main(String[] args) {
        List cards = new ArrayList<>(Arrays.asList("K", "A", "7", "Q", "6", "J", "T"));
        Collections.sort(cards, new CustomComparator());
        System.out.println(cards);

    }
}

Output:

[6, 7, T, J, Q, K, A]

score 1 · Answer 2 · answered Oct 14 '18 at 05:11

@Niklas has answered with a clean code, and if I were you, I'd use that. This is just another answer and if the complexity is not important for you, you can use it. Maybe you get an idea for your other projects.

public List<String> sort(String[] cards) {
    for (int i = 0; i < cards.length; i++) {
        switch (cards[i]) {
            case "T":
                cards[i] = "91";
                break;
            case "J":
                cards[i] = "92";
                break;
            case "Q":
                cards[i] = "93";
                break;
            case "K":
                cards[i] = "94";
                break;
            case "A":
                cards[i] = "95";
                break;
        }
    }
    Arrays.sort(cards);
    for (int i = 0; i < cards.length; i++) {
        switch (cards[i]) {
            case "91":
                cards[i] = "T";
                break;
            case "92":
                cards[i] = "J";
                break;
            case "93":
                cards[i] = "Q";
                break;
            case "94":
                cards[i] = "K";
                break;
            case "95":
                cards[i] = "A";
                break;
        }
    }
    return Arrays.asList(cards);
}

Custom sorting for ArrayList

2 Answers2