使用equals和hashCode方法，toString方法创建Card类

public class Card2 {
/*
时 代 J a v a 公 众 号 - nowjava.com 提 供
*/

    private int rank;

    private int suit;


    public final static int DIAMONDS = 1;

    public final static int CLUBS = 2;

    public final static int HEARTS = 3;

    public final static int SPADES = 4;


    public final static int ACE = 1;

    public final static int DEUCE = 2;

    public final static int THREE = 3;

    public final static int FOUR = 4;
    /**
    N o w J a v a . c o m - 时代Java
    **/

    public final static int FIVE = 5;

    public final static int SIX = 6;

    public final static int SEVEN = 7;

    public final static int EIGHT = 8;

    public final static int NINE = 9;

    public final static int TEN = 10;

    public final static int JACK = 11;

    public final static int QUEEN = 12;

    public final static int KING = 13;


    public Card2(int rank, int suit) {

        this.rank = rank;

        this.suit = suit;

    }


    public int getSuit() {

        return suit;

    }


    public int getRank() {

        return rank;

    }


    public static boolean isValidRank(int rank) {

        return ACE <= rank && rank <= KING;

    }


    public static boolean isValidSuit(int suit) {

        return DIAMONDS <= suit && suit <= SPADES;

    }


    public boolean equals(Object obj) {

        if (obj instanceof Card2) {

            if (((Card2) obj).getRank() == this.rank

                    && ((Card2) obj).getSuit() == this.suit) {

                return true;

            } else {

                return false;

            }

        } else {

            return false;

        }

    }


    public int hashCode() {

        return ((suit - 1) * 13) + rank;

    }


    public String toString() {

        return rankToString(this.rank) + " of " + suitToString(this.suit);

    }


    public static String rankToString(int rank) {

        switch (rank) {

        case ACE:

            return "Ace";

        case DEUCE:

            return "Deuce";

        case THREE:

            return "Three";

        case FOUR:

            return "Four";

        case FIVE:

            return "Five";

        case SIX:

            return "Six";

        case SEVEN:

            return "Seven";

        case EIGHT:

            return "Eight";

        case NINE:

            return "Nine";

        case TEN:

            return "Ten";

        case JACK:

            return "Jack";

        case QUEEN:

            return "Queen";

        case KING:

            return "King";

        default:

            //Handle an illegal argument.  There are generally two ways

            //to handle invalid arguments, throwing an exception (see

            //the section on Handling Exceptions):

            throw new IllegalArgumentException("Invalid rank " + rank);

            //or

            //return null;

        }

    }


    public static String suitToString(int suit) {

        String result = "";

        switch (suit) {

        case DIAMONDS:

            return "Diamonds";

        case CLUBS:

            return "Clubs";

        case HEARTS:

            return "Hearts";

        case SPADES:

            return "Spades";

        default:

            throw new IllegalArgumentException("Invalid suit " + suit);

        }

    }


    public static void main(String... args) {

        new Card2(ACE, DIAMONDS);

        new Card2(KING, SPADES);

    }

}