将数组值列表分配为字符串

Question

I have a program that generates a deck of playing cards and displays seven random cards. I tried to pass the seven cards that were selected into a string, however I only know how to set the entire array to a string, not just the selected 7 cards.

public class PlayedCards{        
      public static void main(String[] args){     
        int[] deck = new int[52];     
        String[] suits = {"Spades", "Clubs", "Diamonds", "Hearts"};    
        String[] ranks = {"Ace", "2", "3", "4", "5", "6", "7", "8", "9", "10", "Jack", "Queen", "King"};    
        for (int a = 0; a < deck.length; a++){
                deck[a]= a;
        }

        for (int a = 0; a <deck.length; a++){
            int order = (int)(Math.random() * deck.length);
            int temp = deck[a];
            deck[a] = deck[order];
            deck[order] = temp;
        }

        for (int a = 0; a < 7; a++){
            String suit = suits[deck[a] / 13];
            String rank = ranks[deck[a] % 13];
            System.out.println(rank + " of " + suit);
        }

        System.out.println(rank + " of " + suit);
     }
}

My questions are:

Are the cards that are displayed the values of 0-6 in my array?

If so, how would I set those values for the array to a separate string that i could then recall for the user as being played?

Answer 1

If you just want to create a String that represents what was played for the player, either directly concatenate each card type and number to a resulting String (implicitly creating a new String on each concatenation) or, better yet, use a StringBuilder to do that and convert to a String at the end. So like this:

StringBuilder sb = new StringBuilder();
for (int a = 0; a < 7; a++) {
...
sb.append(a+1).append(": ").append(rank).append(" of ").append(suit).append("\n");
...
String playedCards = sb.toString();
System.out.println(playedCards);

Answer 2

Better create a immutable card class

class Card
{
     private final int m_suit;
     private final int m_rank;

     public Card( int suit, int rank )
     {
         m_suit = suit;
         m_rank = rank;
     }

     public int getSuit()
     {
          return m_suit;
     }

     public int getRank()
     {
          return m_rank;
     }

}

Now you can create the card instance and pass it around or store it in a ArrayList. For eg

Card card1 = new Card( deck[a] / 13, deck[a] % 13);
System.out.println( rank[card1.getRank()] + " of " + suit[card1.getSuit()]);

Answer 3

public class PlayCards {
public static void main(String[] args) {
    int[] deck = new int[52];
    String[] suits = { "Spades", "Clubs", "Diamonds", "Hearts" };
    String[] ranks = { "Ace", "2", "3", "4", "5", "6", "7", "8", "9", "10",
            "Jack", "Queen", "King" };
    for (int a = 0; a < deck.length; a++) {
        deck[a] = a;
    }

    for (int a = 0; a < deck.length; a++) {
        int order = (int) (Math.random() * deck.length);
        int temp = deck[a];
        deck[a] = deck[order];
        deck[order] = temp;
    }

    Card card = null;
    Card[] cards = new Card[7];
    for (int a = 0; a < 7; a++) {
        card = new Card(suits[deck[a] / 13], ranks[deck[a] % 13]);
        cards[a] = card;
    }

    Player player = new Player();
    player.showCards(cards);
}
}

class Card {
private String suit;
private String rank;

public Card(String suit, String rank) {
    this.suit = suit;
    this.rank = rank;
}

public String toString() {
    StringBuilder card = new StringBuilder();
    card.append(this.rank);
    card.append(',');
    card.append(this.suit);
    return card.toString();
}
}

class Player {
public void showCards(Card[] cards) {
    for (int a = 0; a < 7; a++) {
        System.out.println(cards[a].toString());
    }
}
}