怎么用ArrayList，随机数，实现一个随机抽奖：

一：用ArrayList实现随机抽奖：

/**
 * @ClassName Award
 * @Author 
 * @description : 随机抽奖
 * @Version V1.0
 **/
public class Award {
          
   
    //商品编号
    private String id;
    //概率（0.1代表10%，最多3位小数，即千分之一）
    private float probability;
    //数量（该商品剩余的数量）
    private int count;

    public Award(String id, float probability, int count) {
          
   
        super();
        this.id = id;
        this.probability = probability;
        this.count = count;
    }

    public Award(){
          
   

    }
    //核心逻辑   分配区间   并随机抽取
    public static Award lottery(List<Award> awards){
          
   
        //总的概率区间  可以复习一下floaty与double的区别
        float totalPro = 0f;
        //存储每个奖品新的概率区间
        List<Float> proSection = new ArrayList<Float>();
        proSection.add(0f);
        //遍历每个奖品，设置概率区间，总的概率区间为每个概率区间的总和
        for (Award award : awards) {
          
   
            //每个概率区间为奖品概率乘以1000（把三位小数转换为整）再乘以剩余奖品数量
            totalPro += award.probability * 1000 * award.count;
            proSection.add(totalPro);
        }
        //获取总的概率区间中的随机数
        Random random = new Random();
        float randomPro = (float)random.nextInt((int)totalPro);
        //判断取到的随机数在哪个奖品的概率区间中
        for (int i = 0,size = proSection.size(); i < size; i++) {
          
   
            if(randomPro >= proSection.get(i)
                    && randomPro < proSection.get(i + 1)){
          
   
                return awards.get(i);
            }
        }
        return null;
    }
    public static void main(String[] args) {
          
   
        List<Award> awards = new ArrayList<>();
        awards.add(new Award("a1",0.1f,100));
        awards.add(new Award("a2",0.2f,100));
        awards.add(new Award("a3",0.3f,100));
        awards.add(new Award("a4",0.05f,100));
        awards.add(new Award("a5",0.2f,100));
        for (int i = 0; i < 10; i++) {
          
   
            System.out.println("恭喜您，抽到了：" + lottery(awards).id);
        }
    }
}