对学习的Java集合做一个小练习。现将学习到的知识总结如下：

• 一副标准的Poker有 $13\times 4 + 2 = 54$ 张牌。
• 斗地主游戏下，牌的顺序为：大王、小王、2、A ... 、3。
• 模运算的实际应用场景就类似于这样的发牌的场景。
• java.util.Collections类中的静态方法static void shuffle(List<?> list)的作用:使用默认随机源对指定列表进行置换。在本案例中实现了洗牌的作用。

案例代码如下：

package day0306;

/*
 * 斗地主案例：实现发牌与对每个玩家的牌进行排序
 *
 * */

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;

public class DemoFightTheLandlord {
    public static void main(String[] args) {

        //准备存储牌的Map
        HashMap<Integer, String> poker = new HashMap<>();
        //存储牌的index
        ArrayList<Integer> pokerIndex = new ArrayList<>();
        //4种花色
        String[] colors = {"♠", "♥", "♣", "♦"};
        //13种数字
        String[] numbers = {"2", "A", "K", "Q", "J", "10", "9", "8", "7", "6", "5", "4", "3"};

        int index = 0;
        poker.put(index, "大王");
        pokerIndex.add(index++);
        poker.put(index, "小王");
        pokerIndex.add(index++);

        //1.准备牌
        for (String number : numbers) {
            for (String color : colors) {
                poker.put(index, color + number);
                pokerIndex.add(index++);
            }
        }

        //2.洗牌
        Collections.shuffle(pokerIndex);

        //3.准备玩家和底牌的存储牌的集合
        ArrayList<Integer> player01 = new ArrayList<>();
        ArrayList<Integer> player02 = new ArrayList<>();
        ArrayList<Integer> player03 = new ArrayList<>();
        ArrayList<Integer> diPai = new ArrayList<>();

        //4.发牌
        for (int i = 0; i < pokerIndex.size(); i++) {
            if (i >= 51) {
                diPai.add(pokerIndex.get(i));
            } else {
                if (i % 3 == 0) {
                    player01.add(pokerIndex.get(i));
                }
                if (i % 3 == 1) {
                    player02.add(pokerIndex.get(i));
                }
                if (i % 3 == 2) {
                    player03.add(pokerIndex.get(i));
                }
            }
        }

        //5.对牌进行排序
        Collections.sort(player01);
        Collections.sort(player02);
        Collections.sort(player03);
        Collections.sort(diPai);

        //6.看牌
        lookPoker("张三", player01, poker);
        lookPoker("李四", player02, poker);
        lookPoker("王五", player03, poker);
        lookPoker("底牌", diPai, poker);

    }

    public static void lookPoker(String name, ArrayList<Integer> player, HashMap<Integer, String> poker) {
        System.out.print(name + "： ");
        for (Integer idx : player) {
            System.out.print(poker.get(idx) + " ");
        }
        System.out.println();
    }
}