Collections

Java has a class called java.util.Collections that defines all of the built in data types, but also provides some helper methods.

Helper Methods

public static void main() {
    Card[] cardArray = new Card[13];
    Card aceOfHearts = Card.getFaceCard(Card.Suit.HEART, 'A');
    Arrays.fill(cardArray, aceOfHearts);
    Card.printDeck(Arrays.asList(cardArray), "Aces of Hearts", 1);

    List<Card> cards = new ArrayList<>(52);
    // doesn't add any cards because capacity is 52 but size is 0
    Collections.fill(cards, aceOfHearts);
    System.out.println(cards);
    System.out.println("cards.size() = " + cards.size());

    // Returns a list with n copies
    List<Card> acesOfHearts = Collections.nCopies(13, aceOfHearts);
    Card.printDeck(acesOfHearts, "Aces of Hearts", 1);

    Card kingOfClubs = Card.getFaceCard(Card.Suit.CLUB, 'K');
    List<Card> kingsOfClubs = Collections.nCopies(13, kingOfClubs);
    Card.printDeck(kingsOfClubs, "Kings of Clubs", 1);

    // adds elements to empty lists
    Collections.addAll(cards, cardArray);
    Collections.addAll(cards, cardArray);
    Card.printDeck(cards, "Card Collection with Aces added", 2);

    // copyies over elements at the same index
    // in this example we have 26 cards already, so only the first 13 get overwritten
    Collections.copy(cards, kingsOfClubs);
    Card.printDeck(cards, "Card Collection with Kings copied", 2);

    Collections.shuffle(cards);
    Collections.reverse(cards);

    var sortingAlgorithm = Comparator.comparing(Card::rank)
        .thenComparing(Card::suit);
    Collections.sort(cards, sortingAlgorithm);

    List<Card> subList = new ArrayList<>(cards.subList(0,4));
    int subListIndex = Collections.indexOfSubList(cards, subList);

    // Returns true if no elements in second list are found in first list
    boolean disjoint = Collections.disjoint(cards, subList);
}