CODEWITHSUNDEEP
javaarraysstringsorting
MadcapClover
MadcapClover

Reputation: 29

Selection Sorting String Arrays (Java)

I need to know how to sort an array of Strings, I know how to do a selection sort, however I have BOTH numbers and letters in the array. The idea is to sort a hand of cards. This is what I have ... 

clubsArry[0] = 7C

clubsArry[1] = AC

clubsArry[2] = TC

clubsArry[3] = KC

The second character represents the suit of the card, in this case clubs, and the first character is the card value (the T represents Ten, K is king, A is ace, etc.), so for the clubsArry[0] , the card is a 7 of clubs. When I sort it and print, the output I get is ....

7C

AC

KC

TC

So all the cards that that have a letter in the first position get sorted properly but I still have the 7 of clubs that is at the top of the output. The output that I want is ...

AC

KC

TC

7C

The way I tried to sort it was by doing this:

public void sortClubs() // A selection sort, that will sort out the clubs 
{
    for (int i = 1; i < clubsArry.length; i++)
    {
        int s = i-1;
        for (int j = i; j < clubsArry.length; j++)
        {
            if (clubsArry[j].compareTo(clubsArry[s]) < 0)
            {
                 s = j;
            }
        }
         String temp = clubsArry[i-1];
         clubsArry[i-1] = clubsArry[s];
         clubsArry[s] = temp;
    }
}

I just cant seem to figure it out, I was going to convert it into a char array and then cast into an int and the sort and convert it all back, but I figure there must be a simpler way to do this, If there is a way at all.

Thanks for all the help :)

MadcapClover

Upvotes: 2

Views: 6623

Answers (4)

wolfcastle
wolfcastle

Reputation: 5930

Use a Comparator, then the Arrays.sort() method. This should help with your coding as it lets you focus on a single thing: how do I order 2 different cards? You will have to hard-code in the ordering somehow, here is one way to do it. I haven't tested it; and it only sorts based on the first character. If the first characters are the same, then you should look at the second charater.

import java.util.Comparator;

public class CardComparator implements Comparator<String> {

    private static final List<Character> CARD_ORDER = Arrays.asList( 
    'A', 'K', 'Q', 'J', '1', '9', '8', '7', '6', '5', '4', '3', '2');

    @Override
    public int compare(String card1, String card2) {
        if( card1.equals(card2)) {
            return 0;
        }

        int firstIndex = CARD_ORDER.indexOf(card1.charAt(0));
        int secondIndex = CARD_ORDER.indexOf(card2.charAt(0));

        return firstIndex - secondIndex;
    }
}

Upvotes: 3

BillThor
BillThor

Reputation: 7576

Use Collections to do this for you. A sorted collection like a TreeMap will sort as you fill it. Collections with a sort method can be sorted after loading.

If you need a custom sort order, you can provide your own Comparator. Arrays allow you to provide your own Comparator. TreeMaps can be created with a Comparator.

If you create your a class you wish to be sortable you should implement the Comparable interface.

Upvotes: 1

rsp
rsp

Reputation: 23373

You can use String::charAt(int) to retrieve the characters at positions 0 and 1 and use those to compare.

Upvotes: 1

javing
javing

Reputation: 12423

Have a look at this great link related to array sorting: http://www.leepoint.net/notes-java/data/arrays/70sorting.html Arrays class has few static methods very useful maybe some of them suit your needs.

Upvotes: 1

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