1 package Demo_1.Test_1;
 2 
 3 import java.math.BigDecimal;
 4 import java.util.Random;
 5 
 6 /**
 7  * @描述：微信红包算法TEST
 8  * @author BrokenColor
 9  * @date 2017年3月2日上午11:27:36
10  */
11 public class WeixinHB {
12 
13     double TOTAL = 10;//红包总金额
14     int NUM = 8;//抢红包人数
15     double MIN = 0.01;//每人最少分的金额
16     double safe_total ;
17     double money ;
18     Random rand = new Random();
19     public void calculation(){
20         for (int i = 1; i < NUM; i++) {
21             
22             safe_total = (TOTAL-(NUM-i)*MIN)/(NUM-i);//计算安全上限
23             
24             money = rand.nextDouble()*(safe_total-MIN)+MIN;
25             
26             money =(double)Math.round(money*100)/100;//保留两位小数
27             
28             //直接相减会有double数据类型相减的问题
29             TOTAL = this.sub(TOTAL, money);
30             
31             System.out.println("第"+i+"次红包："+money+"元,剩余："+TOTAL+"元");
32         }
33         System.out.println("第"+NUM+"次红包："+TOTAL+"元,剩余：0元");
34     }
35     //double 数相减
36      public double sub(double d1,double d2){ 
37          BigDecimal bd1 = new BigDecimal(Double.toString(d1)); 
38          BigDecimal bd2 = new BigDecimal(Double.toString(d2)); 
39          return bd1.subtract(bd2).doubleValue(); 
40      } 
41     
42     public static void main(String[] args) {
43         // TODO Auto-generated method stub
44         WeixinHB hb = new WeixinHB();
45         hb.calculation();
46     }
47 
48 }