Java随机播放卡座

Question

I am having problem getting my code to shuffle the deck. I think i have the syntax for collections.shuffle wrong. The code I currently have is not shuffling the deck. Below please find the deck class and the card class. The deck class holds the collections.shuffle method.

Deck class

public class Deck {

    private Card[] deck = new Card[52];
    private int topCard;

    Deck() {

        topCard = 0;

        for (int i = 0; i < deck.length; i++)
            deck[i] = new Card(i);

    }

    public void shuffle() {

        topCard = 0;

        Collections.shuffle(Arrays.asList(deck));
    }

    public Card dealCard() {
        Card theCard;
        if (topCard < deck.length) {
            theCard = deck[topCard];
            topCard++;
        }
        else
            theCard = null;

        return theCard;
    }
}

Card Class

public class Card {

    private int cardNum;
    final static String[] suits = {"Spades", "Hearts", "Diamonds", "Clubs"};
    final static String[] ranks = {"Ace", "2", "3","4","5","6","7","8", "9","10", "Jack", "Queen", "King"};

    Card (int theCard) {
        setCardNum (theCard);
    }

    public void setCardNum (int theCard) {
        cardNum = (theCard >= 0 && theCard <= 52)? theCard: 0;
    }

    public int getCardNum() {
        return cardNum;
    }

    public String toString() {
        return ranks[cardNum%13] + " of " + suits[cardNum/13];
    }

    public String getSuit() {
        return suits[cardNum/13];
    }

    public String getRank() {
        return ranks[cardNum%13];
    }

    public int getValue() {
        return cardNum%13;
    } 
}

Answer 1

Here is a sample code for a similar question where we were asked not to use any built-in function to shuffle the deck but was allowed to use Math.random().

import java.util.*;

class Card {
    private String rank;
    private String suit;

    public Card(String r,String s) {
        rank=r;
        suit=s;
    }

    public String getRank() {
        return rank;    
    }

    public String getSuit() {
        return suit;
    }

    public String toString() {
        return rank+" of "+suit;
    }   
}

class Deck {
    private ArrayList<Card> deck;
    private String[] ranks ={"ACE","2","3","4","5","6","7","8","9","10","JACK","QUEEN","KING"};
    private String[] suits ={"SPADE","HEART","CLUB","DIAMOND"};

    public Deck() {
        deck = new ArrayList<Card>();
        for(int i=0;i<suits.length;i++) {
            for(int j=0;j<ranks.length;j++) {
                deck.add(new Card(ranks[j],suits[i]));
            }
        }
    }

    public void showCards() {
        System.out.println("\n\n Showing Cards !!!");
        int i=1;
        for(Card c:deck) {
            System.out.println("Card "+(i++)+" : "+c);
        }
    }

    public  void shuffle() {
        ArrayList<Card> temp = new ArrayList<Card>();
        while(!deck.isEmpty()) {
            int loc=(int)(Math.random()*deck.size());
            temp.add(deck.get(loc));
            deck.remove(loc);   
        }
        deck=temp;
    }       

}

public class Game {
    public static void main(String[] args) {
        Deck myDeck = new Deck();
        myDeck.showCards();
        myDeck.shuffle();
        myDeck.showCards();
    }

}