doubts in enum and generalized code

[AshutoshP Patil]

hi i am not unable to understand the below code which uses enum with generalized code
can anybody please make me understand the below code?

List<Card> prototypeDeck = new ArrayList<Card>(52);
what is the significance of 52 here and where it is passed ?


kindly explain, thanks

Card.java

    
import java.util.*;
    public class Card implements Comparable<Card>, java.io.Serializable {
        public enum Rank { DEUCE, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE, TEN,JACK, 
    QUEEN, KING, ACE }
        public enum Suit { CLUBS, DIAMONDS, HEARTS, SPADES }
        private final Rank rank;
        private final Suit suit;
        private Card(Rank rank, Suit suit) {
            if (rank == null || suit == null)
                throw new NullPointerException(rank + ", " + suit);
            this.rank = rank;
            this.suit = suit;
        }
        public Rank rank() { return rank; }
        public Suit suit() { return suit; }
        public String toString() { return rank + " of " + suit; }
        
        public int compareTo(Card c) {
            int suitCompare = suit.compareTo(c.suit);
            return (suitCompare != 0 ? suitCompare : rank.compareTo(c.rank));
        }
        private static final List<Card> prototypeDeck = new ArrayList<Card>(52);
        static {
            for (Suit suit : Suit.values())
                for (Rank rank : Rank.values())
                    prototypeDeck.add(new Card(rank, suit));
        }
        
        public static List<Card> newDeck() {
            return new ArrayList<Card>(prototypeDeck);
        }
    }

Deal.java

    import java.util.*;
    class Deal {
        public static void main(String args[]) {
    		int numHands     = Integer.parseInt(args[0]);
    		int cardsPerHand = Integer.parseInt(args[1]);
    		List<Card> deck  = Card.newDeck();
    		Collections.shuffle(deck);
    		for (int i=0; i < numHands; i++)
                System.out.println(dealHand(deck, cardsPerHand));
        	}
       
        public static <E extends Comparable<E>> ArrayList<E>
                dealHand(List<E> deck, int n) {
            int deckSize = deck.size();
            List<E> handView = deck.subList(deckSize - n, deckSize);
            ArrayList<E> hand = new ArrayList<E>(handView);
            handView.clear();
            Collections.sort(hand);
            return hand;
        }
    }
   

[Ganesh Gowtham]

HI

This 52 is initialCapacity sent to ArrayList(int initialCapacity) .

  /**
     * Constructs an empty list with the specified initial capacity.
     *
     * @param   initialCapacity   the initial capacity of the list.
     * @exception IllegalArgumentException if the specified initial capacity
     *            is negative
     */
    public ArrayList(int initialCapacity) {
	super();
        if (initialCapacity < 0)
            throw new IllegalArgumentException("Illegal Capacity: "+
                                               initialCapacity);
	this.elementData = (E[])new Object[initialCapacity];
    }  

[AshutoshP Patil]

@ganesh thanks
i got it is one more constructor which takes int argument

can you explain me the flow of this code when we run the class Deal
by java Deal 4 5

[David Newton]

Have you traced the program through by hand? Where did you get stuck?

[AshutoshP Patil]

hi
@david
i am explaining what i have understood . Please rectify me where i am wrong.

1) when there is a call to Card.newDeck() the Card class is initialized in the following order

static initializations
(a) each enum constants are constructed by default constructor of Rank,Suit respectively
(b)Then prototypeDeck is constructed from ArrayList of 52
(c)then the static block is run which adds card object to prototypeDeck in add() by getting the enum values from Rank,Suit

2)after the call to Card.newDeck(), deck gets a list of card objects then it randomizes the list by shuffle()

3)After that dealHand(deck,cardsPerHand) is evaluated for each iteration before passing it to System.out.println()
inside the body of dealHand, it returns the sorted array list (hand) which is made out using the sublist got out of deck ,
the sorting is defined in the compareTo() of Card class which first prioritizes suit then based on rank
(if they are not same suit type )

4)since the card class uses toString() , the output is printed in the manner " rank of suit "


but i am some where missing the call to

public Rank rank() { return rank;}
and
public Suit suit() { return suit;}


thanks in advance for reading patiently.

[David Newton]

Just because a method is defined doesn't mean it's called.

[AshutoshP Patil]

thanks david.
i thought i am missing the call to these two methods.ok