Repeat Values in array and shuffle it

Question

I'm having trouble shuffling a two dimensional array in Java. There are 10 base cards.

This is the array:

String[][] Cards = new String[][] {
        {"CardType1","CardName1","CardProperties"},
        {"CardType1","CardName2","CardProperties"},
        {"CardType1","CardName3","CardProperties"},
        {"CardType2","CardName4","CardProperties"},
        {"CardType2","CardName5","CardProperties"},
        {"CardType2","CardName6","CardProperties"},
        {"CardType2","CardName7","CardProperties"},
        {"CardType3","CardName8","CardProperties"},
        {"CardType3","CardName9","CardProperties"},
        {"CardType3","CardName10","CardProperties"}
        };

Each card must replicate itself 4 times to complete a deck with 40 cards and then shuffle it. How can I use Java to do this?

This is the wrong approach. Use an `Object` like `Card` to store the properties. Then use a `List` rather than an array. Use a loop to populate the `List` and then `Collections.shuffle` to shuffle the `List`. — Boris the Spider, Aug 24 '14 at 13:22

score 2 · Accepted Answer · edited May 23 '17 at 12:13

2

First, you have a little object phobia. Lets start with an enum for CardType:

public enum CardType {
    TYPE_1,
    TYPE_2,
    TYPE_3,
    //etc...
    ;
}

Not sure what card name is, but lets leave it as a String. Not sure what card properties is either - lets call this a Map<String, String>. So our Card class would be something like:

public class Card {
    private final CardType cardType;
    private final String cardName;
    private final Map<String, String> properties = new HashMap<>();

    Card(final CardType cardType, final String cardName) {
        this.cardType = cardType;
        this.cardName = cardName;
    }

    public Card setProperty(final String name, final String value) {
        properties.put(name, value);
        return this;
    }

    public String getProperty(final String name) {
        return properties.get(name);
    }
}

Add getters and setters, also toString, equals and hashCode methods. Possibly make Card implement Comparable<Card>.

So to create a Card you would call:

final Card card = new Card(CardType.TYPE_1, "CardName1");

And to set properties, because the method is chainable you can do:

final Card card = new Card(CardType.TYPE_1, "CardName1").
        setProperty("prop1", "thing").
        setProperty("prop2", "stuff");

Now, to create your deck, you need 4 cards of each type, this is simple. With Java 8:

final List<Card> deck = Stream.of(CardType.values()).
        flatMap(type -> IntStream.rangeClosed(1, 4).mapToObj(num -> new Card(type, "CardName" + num))).
        collect(toList());

Pre Java 8 to create the List you can use explicit loops:

final List<Card> deck = new LinkedList<>();
for (final CardType cardType : CardType.values()) {
    for (int i = 1; i <= 4; ++i) {
        final Card card = new Card(cardType, "CardName" + i);
        deck.add(card);
    }
}

In order to shuffle a Collection simply use Collections.shuffle like so:

Collections.shuffle(deck);

edited May 23 '17 at 12:13

Community

1
1

answered Aug 24 '14 at 13:47

Boris the Spider

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Thank you @Boris! One more thing, where do I put `Collections.shuffle(deck);` – user3326060 Aug 24 '14 at 14:35
What do you mean? Where are you putting the rest of the code? You put it where you want to shuffle the deck... – Boris the Spider Aug 24 '14 at 14:39
Forget that one,. how to get the card and it's properties from `deck` and `System.out.print` it? – user3326060 Aug 24 '14 at 14:55
In what sense get a card. Draw the top card from the deck? Get some particular card? You need to be more specific with your questions... – Boris the Spider Aug 24 '14 at 14:57
*How to get a card from top of the deck and `System.out.print` it's name and properties? – user3326060 Aug 24 '14 at 15:00
1

I would suggest that you first read [this](http://docs.oracle.com/javase/tutorial/collections/interfaces/list.html) - it will explain what a `List` is. And what it can do. If you just want to see the top card you can use `List.get(0)`. If you want to _remove_ the top card the `List.remove(0)` which will also give you the card removed. – Boris the Spider Aug 24 '14 at 15:05
So if I want to get a card's name and property from another class, I would use `Card.deck.get(0)`? – user3326060 Aug 24 '14 at 15:30
Why is `deck` a `static` member of `Card`? I don't really understand where you are getting this from. – Boris the Spider Aug 24 '14 at 15:31
This is your code that I combined together, I don't know if it's correct but here it is [link](http://pastebin.com/qkG55hiH) – user3326060 Aug 24 '14 at 15:39
I don't believe that that code will compile. You need to read some basic Java tutorials. – Boris the Spider Aug 24 '14 at 15:41
I'd go with that suggestion, but can you correct the code on that link? – user3326060 Aug 24 '14 at 15:45

Repeat Values in array and shuffle it

1 Answers1