How to operate the poker game by Java?

Question

I’ve learned Java for 1 month. This time, I’d like to create a poker game. There are two questions about my program. I hope somebody can help me to fix it.

1. Each card has it value, for A as 1, king as 10, but I find out that this is a String array. How could I give each “String value “as “int value” so that I can do the operation?

   String[] suits = { "hearts", "spades", "diamonds", "clubs" };
   String[] number = {"A","2","3"......};
   

2. I hope this system can use random number to chose cards at first, and second time when it run, it can void previous number (There have 52 card). Does there has something that I can do to figure out this problem?

Answer 1

I don't think you want a String array for cards, what you really need is an enum. Here's a nice tutorial on enum types: http://docs.oracle.com/javase/tutorial/java/javaOO/enum.html

Also, here's how you generate random numbers in Java: http://javamex.com/tutorials/random_numbers/

Answer 2

For your first question, you could map a card name to its value:

Map<String, Integer> values = new HashMap<String, Integer>();
values.put("A", 11);
values.put("2", 2);
// ...
values.put("King", 10);

// lookup a value:
int kingValue = values.get("King");

For the second, I'd rely on java shuffle function. Create a list of all cards

ArrayList<Card> deck = someMagicMethodToPopulateTheList();

and then simply shuffle the deck

Collections.shuffle(deck);

Now you can iterate through the deck and you will see the cards in a random order:

for (Card card:deck) {
  System.out.println(card);
}

Note: the Card class does not extist (yet). I simply invented the name to keep it simple)

Answer 3

this is probably more than you need, but you can do a lot with enums:

package sample;
import java.util.*;
enum Rank { 
    joker(new Character('*'),"Joker"),aceLow(new Character('a'),"Ace(low)"),deuce(new Character('2'),"Deuce"),trey(new Character('3'),"Trey"),four(new Character('4'),"Four"),five(new Character('5'),"Five"),six(new Character('6'),"Six"),seven(new Character('7'),"Seven"),eight(new Character('8'),"Eight"),nine(new Character('9'),"Nine"),ten(new Character('T'),"Ten"),jack(new Character('J'),"Jack"),queen(new Character('Q'),"Queen"),king(new Character('K'),"King"),aceHigh(new Character('A'),"Ace");
    Rank(final Character c,final String s) {
        this.c=c;
        this.s=s;
    }
    public static Rank fromInt(int n) {
        for(Rank r:Rank.values())
            if(r.ordinal()==n)
                return r;
        return null;
    }
    public static Rank fromCharacter(char c) {
        for(Rank r:Rank.values())
            if(r.c==c)
                return r;
        return null;
    }
    public static Rank[] fromCharacters(final String cards) {
        final Rank[] rank=new Rank[5];
        for(int i=0;i<5;i++)
            rank[i]=Rank.fromCharacter(cards.charAt(i));
        return rank;
    }
    public Character toCharacter() {
        return c;
    }
    public String toString() {
        return s;
    }
    public static String toString(final Rank[] rank) {
        String s="";
        for(Rank r:rank)
            s+=r.toCharacter();
        return s;
    }
    final Character c;
    final String s;
}
enum Suit {
    joker(new Character('*'),"Joker"),clubs(new Character('c'/* try character for a real dimond? */),"Club"),diamonds(new Character('d'),"Diamond"),hearts(new Character('h'),"Heart"),spades(new Character('s'),"Spade");
    Suit(final Character c,final String s) {
        this.c=c;
        this.s=s;
    }
    public static Suit fromCharacter(char c) {
        for(Suit s:Suit.values())
            if(s.c==c)
                return s;
        return null;
    }
    public Character toCharacter() {
        return c;
    }

    public String toString() {
        return s;
    }
    public static String toString(final Suit[] suit) {
        String s_="";
        for(Suit s:suit)
            s_+=s.toCharacter();
        return s_;
    }
    public static boolean areSuited(final Suit[] suit) {
        final int n=suit.length;
        for(int i=0;i<n-1;i++)
            if(suit[i]!=suit[i+1])
                return false;
        return true;
    }
    final Character c;
    final String s;
}
enum Card {
    joker(Rank.joker,Suit.joker),
    aceLowOfClubs(Rank.aceLow,Suit.clubs),
    aceLowOfDiamonds(Rank.aceLow,Suit.diamonds),
    aceLowOfHearts(Rank.aceLow,Suit.hearts),
    aceLowOfSpades(Rank.aceLow,Suit.spades),
    dueceOfClubs(Rank.deuce,Suit.clubs),
    dueceOfDiamonds(Rank.deuce,Suit.diamonds),
    dueceOfHearts(Rank.deuce,Suit.hearts),
    dueceOfSpades(Rank.deuce,Suit.spades),
    treyOfClubs(Rank.trey,Suit.clubs),
    treyOfDiamonds(Rank.trey,Suit.diamonds),
    treyOfHearts(Rank.trey,Suit.hearts),
    treyOfSpades(Rank.trey,Suit.spades),
    fourOfClubs(Rank.four,Suit.clubs),
    fourOfDiamonds(Rank.four,Suit.diamonds),
    fourOfHearts(Rank.four,Suit.hearts),
    fourOfSpades(Rank.four,Suit.spades),
    fiveOfClubs(Rank.five,Suit.clubs),
    fiveOfDiamonds(Rank.five,Suit.diamonds),
    fiveOfHearts(Rank.five,Suit.hearts),
    fiveOfSpades(Rank.five,Suit.spades),
    sixOfClubs(Rank.six,Suit.clubs),
    sixOfDiamonds(Rank.six,Suit.diamonds),
    sixOfHearts(Rank.six,Suit.hearts),
    sixOfSpades(Rank.six,Suit.spades),
    sevenOfClubs(Rank.seven,Suit.clubs),
    sevenOfDiamonds(Rank.seven,Suit.diamonds),
    sevenOfHearts(Rank.seven,Suit.hearts),
    sevenOfSpades(Rank.seven,Suit.spades),
    eightOfClubs(Rank.eight,Suit.clubs),
    eightOfDiamonds(Rank.eight,Suit.diamonds),
    eightOfHearts(Rank.eight,Suit.hearts),
    eightOfSpades(Rank.eight,Suit.spades),
    nineOfClubs(Rank.nine,Suit.clubs),
    nineOfDiamonds(Rank.nine,Suit.diamonds),
    nineOfHearts(Rank.nine,Suit.hearts),
    nineOfSpades(Rank.nine,Suit.spades),
    tenOfClubs(Rank.ten,Suit.clubs),
    tenOfDiamonds(Rank.ten,Suit.diamonds),
    tenOfHearts(Rank.ten,Suit.hearts),
    tenOfSpades(Rank.ten,Suit.spades),
    jackOfClubs(Rank.jack,Suit.clubs),
    jackOfDiamonds(Rank.jack,Suit.diamonds),
    jackOfHearts(Rank.jack,Suit.hearts),
    jackOfSpades(Rank.jack,Suit.spades),
    queenOfClubs(Rank.queen,Suit.clubs),
    queenOfDiamonds(Rank.queen,Suit.diamonds),
    queenOfHearts(Rank.queen,Suit.hearts),
    queenOfSpades(Rank.queen,Suit.spades),
    kingOfClubs(Rank.king,Suit.clubs),
    kingOfDiamonds(Rank.king,Suit.diamonds),
    kingOfHearts(Rank.king,Suit.hearts),
    kingOfSpades(Rank.king,Suit.spades),
    aceOfClubs(Rank.aceHigh,Suit.clubs),
    aceOfDiamonds(Rank.aceHigh,Suit.diamonds),
    aceOfHearts(Rank.aceHigh,Suit.hearts),
    aceOfSpades(Rank.aceHigh,Suit.spades);
    private Card(Rank rank,Suit suit) {
        this.rank=rank;
        this.suit=suit;
    }

    public Rank rank() {
        return rank;
    }
    public Suit suit() {
        return suit;
    }
    public String toString() {
        if(rank.equals(Rank.joker)||suit.equals(Suit.joker))
            return "Joker";
        else return rank+" of "+suit+'s';
    }
    public static String toString(final Card[] card) {
        String s=new String();
        for(int i=0;i<card.length;i++) {
            if(i>0)
                s+=", ";
            s+=card[i].toCharacters();
        }
        return s;
    }
    public String toCharacters() {
        return ""+rank().toCharacter()+suit().toCharacter();
    }
    public static Card instance(Rank rank,Suit suit) { // some hack for speed
        final int n=4*rank.ordinal()+suit.ordinal();
        //System.out.println(rank+" "+suit+" "+n);
        return element[4*rank.ordinal()+suit.ordinal()];
    }
    static Card[] create(int standards,int jokers) {
        int cards=0;
        Card card[]=new Card[standards*52+jokers];
        for(int i=0;i<standards;i++)
            for(Suit suit:EnumSet.range(Suit.clubs,Suit.spades))
                for(Rank rank:EnumSet.range(Rank.deuce,Rank.aceHigh))
                    card[cards++]=instance(rank,suit);
        for(int i=0;i<jokers;i++)
            card[cards++]=instance(Rank.joker,Suit.joker);
        return card;
    }
    private final Rank rank;
    private final Suit suit;
    private static final Card element[]={joker,joker,joker,joker,joker,aceLowOfClubs,aceLowOfDiamonds,aceLowOfHearts,aceLowOfSpades,dueceOfClubs,dueceOfDiamonds,dueceOfHearts,dueceOfSpades,treyOfClubs,treyOfDiamonds,treyOfHearts,treyOfSpades,fourOfClubs,fourOfDiamonds,fourOfHearts,fourOfSpades,fiveOfClubs,fiveOfDiamonds,fiveOfHearts,fiveOfSpades,sixOfClubs,sixOfDiamonds,sixOfHearts,sixOfSpades,sevenOfClubs,sevenOfDiamonds,sevenOfHearts,sevenOfSpades,eightOfClubs,eightOfDiamonds,eightOfHearts,eightOfSpades,nineOfClubs,nineOfDiamonds,nineOfHearts,nineOfSpades,tenOfClubs,tenOfDiamonds,tenOfHearts,tenOfSpades,jackOfClubs,jackOfDiamonds,jackOfHearts,jackOfSpades,queenOfClubs,queenOfDiamonds,queenOfHearts,queenOfSpades,kingOfClubs,kingOfDiamonds,kingOfHearts,kingOfSpades,aceOfClubs,
        aceOfDiamonds,aceOfHearts,aceOfSpades};
}

Answer 4

What you should be considering for this sort of classification is Enums:

public enum Suit {
  Hearts, Spades, Diamonds, Clubs;
}
public enum Card {
  A, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, J, Q, K;
}

This benefits your situation since enums can be assigned value easily, to whatever you like, and then they can be compared based on this value. In fact, the Java documentation provides a card game for the introduction to enums.