1. 准备一张牌

一张扑克牌里面有点数和花色，

class Card {
    public int rank;//点数
    public String suit;//花色

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

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

2. 拿一副牌出来

先搞一个数组存放牌的花色

    public static final String [] suits = {"♥", "♠", "♣", "♦"};

再循环一副牌出来

    public List<Card> buyDeskCard() {
        List<Card> cards = new ArrayList<>();
        for (int i = 1; i <= 13; i++) {
            for (int j = 0; j < 4; j++) {
                Card card = new Card(i,suits[j]);
                cards.add(card);
            }
        }
        return cards;
    }

试着打印看一下

    public static void main(String[] args) {
        CardDemo cardDemo = new CardDemo();
        List<Card> ret = cardDemo.buyDeskCard();
        System.out.println(ret);
    }

3.洗牌（打乱牌的顺序）

循环让 i 存这个牌的数组从后到前开始循环，让 i 从 0 到 i-1 的某一个数组下标的牌交换，交换完成后i– ，一直循环完成后，洗牌也就完成了、

洗牌

    public void shuffle(List<Card> cards) {

        for (int i = cards.size()-1; i > 0; i--) {
            //产生随机数
            Random random = new Random();
            int index = random.nextInt(i);
            //交换
            swap(cards,index,i);
        }
    }

交换

    private void swap(List<Card> cards, int i, int j) {
        Card tmp = cards.get(i);
        cards.set(i,cards.get(j));
        cards.set(j,tmp);
    }

洗牌的方法写好了，我们试着调用一下

    public static void main(String[] args) {
        CardDemo cardDemo = new CardDemo();
        List<Card> ret = cardDemo.buyDeskCard();
        cardDemo.shuffle(ret);
        System.out.println(ret);
    }

4.开始发牌

如果是三个人每个人拿五张牌，这样发牌的话

发牌也就是将洗好的牌从数组中删除

而且发牌也要考虑，这张牌发给了谁，要能对应上

    public List<List<Card>> test(List<Card> cards) {
        //new三个人出来
        List<Card> hand1 = new ArrayList<>();
        List<Card> hand2 = new ArrayList<>();
        List<Card> hand3 = new ArrayList<>();

        List<List<Card>> hands = new ArrayList<>();
        hands.add(hand1);
        hands.add(hand2);
        hands.add(hand3);
        //轮流拿五张牌
        for (int i = 0; i < 5; i++) {
            for (int j = 0; j < 3; j++) {
                Card card = cards.remove(0);
                hands.get(j).add(card);
            }
        }
        return hands;
    }

写好发牌的方法，试着调用一下

    public static void main(String[] args) {
        CardDemo cardDemo = new CardDemo();
        List<Card> ret = cardDemo.buyDeskCard();
        System.out.println(ret);
        System.out.println("洗牌：");
        cardDemo.shuffle(ret);
        System.out.println(ret);
        System.out.println("发牌：");
        List<List<Card>> ret2 = cardDemo.test(ret);
        for (int i = 0; i < ret2.size(); i++) {
            System.out.println("第"+i+"个人的牌："+ ret2.get(i));
        }
        System.out.println("剩余的牌：");
        System.out.println(ret);
    }