需求： 使用LinkedList存储一副扑克牌，然后实现洗牌功能。

import java.util.LinkedList;
import java.util.Random;

/*
需求： 使用LinkedList存储一副扑克牌，然后实现洗牌功能。

*/
//扑克类
class Poker{

    String  color; //花色

    String num;    //点数

    public Poker(String color, String num) {
        super();
        this.color = color;
        this.num = num;
    }

    @Override
    public String toString() {
        return "{"+color+num+"}";
    }
}

public class Demo2 {

    public static void main(String[] args) {
        LinkedList pokers = createPoker();
        shufflePoker(pokers);
        showPoker(pokers);
    }

    //洗牌的功能
    public static void shufflePoker(LinkedList pokers){
        //创建随机数对象
        Random random = new Random();
        for(int i = 0 ; i <100; i++){
            //随机产生两个索引值
            int index1 = random.nextInt(pokers.size());
            int index2 = random.nextInt(pokers.size());
            //根据索引值取出两张牌，然后交换两张牌的顺序
            Poker poker1 = (Poker) pokers.get(index1);
            Poker poker2 = (Poker) pokers.get(index2);
            pokers.set(index1, poker2);
            pokers.set(index2, poker1);
        }

    }

    //显示扑克牌
    public static void showPoker(LinkedList pokers){
        for(int i = 0 ; i<pokers.size() ; i++){
            System.out.print(pokers.get(i));
            //换行
            if(i%10==9){
                System.out.println();
            }
        }

    }

    //生成扑克牌的方法
    public static LinkedList createPoker(){
        //该集合用于存储扑克对象。
        LinkedList list = new LinkedList();
        //定义数组存储所有的花色与点数
        String[] colors = {"黑桃","红桃","梅花","方块"};
        String[] nums = {"A","2","3","4","5","6","7","8","9","10","J","Q","K"};
        for(int i = 0 ; i < nums.length ; i++){
            for(int j = 0 ; j<colors.length ; j++){
                list.add(new Poker(colors[j], nums[i]));
            }
        }
        return list;
    }

}