Question

How do you create a constructor that takes and array of cards and adds them to a hand which is an arrayList? Below are my 3 constructors so far…

“The class should provide a default constructor(creates an empty hand), a constructor that takes an array of cards and adds them to the hand and a constructor that takes a different hand and add the cards to this hand”

Updated:

  public class Hand {

    private List<Hand> hand = new ArrayList<Hand>();

    public Hand(){
        hand = new ArrayList<Hand>();
    }

    public Hand(Card[] cards){
        //this.hand.addAll(Arrays.asList(cards));
        //this.hand = new ArrayList<Hand>(Arrays.asList(cards));]
    }

    public Hand(Hand cards){
         this.hand = Arrays.asList(cards);
    }   
  }

Answer 1

You should have the list as the instance variable in the Hand class:

public class Hand {
    private List<Card> cards;

    public Hand(Card[] cards) {
        this.cards = Arrays.asList(cards);
    }
}

Currently you are declaring a local variable which goes out-of-scope immediately after the constructor returns.

Update

It doesn’t make sense to have a list of Hands within the Hand class itself. IMO, it would be better to let each Player keep their own Hand.

As far as understand, you want to have a constructor that initializes the list of cards, and a method to add cards to that list. Something as follows:

public class Hand {
    private List<Card> cards;

    public Hand() {
        this.cards = new ArrayList<Card>();
    }

    public void addCards(Card... cards) {
        this.cards.addAll(Arrays.asList(cards));
    }
}

Following are the constructors:

public class Hand {
    private List<Card> cards;

    //constructor to create an empty hand
    public Hand() { 
        this.cards = new ArrayList<Card>();
    }

    //constructor to create an empty hand and add all provided cards to it
    public Hand(Card[] cards) {
        this();
        this.cards.addAll(Arrays.asList(cards));
    }

    //constructor to create an empty hand and add all cards in the provided hand
    public Hand(Hand hand) {
        this();
        this.cards.addAll(hand.getCards());
    }
}