java根据概率生成数字

 /**
  * JAVA 返回随机数，并根据概率、比率
  * @author zhanglei
  *
  */
 public class MathRandom
 {
  /**
      * 0出现的概率为%50
      */
  public static double rate0 = 0.50;
  /**
      * 1出现的概率为%20
      */
  public static double rate1 = 0.20;
  /**
      * 2出现的概率为%15
      */
  public static double rate2 = 0.15;
  /**
      * 3出现的概率为%10
      */
  public static double rate3 = 0.10;
  /**
      * 4出现的概率为%4
      */
  public static double rate4 = 0.04;
  /**
      * 5出现的概率为%1
      */
  public static double rate5 = 0.01;

  /**
   * Math.random()产生一个double型的随机数，判断一下
   * 例如0出现的概率为%50，则介于0到0.50中间的返回0
      * @return int
      *
      */
  private int PercentageRandom()
  {
   double randomNumber;
   randomNumber = Math.random();
   if (randomNumber >= 0 && randomNumber <= rate0)
   {
    return 0;
   }
   else if (randomNumber > rate0  && randomNumber <= rate0 + rate1)
   {
    return 1;
   }
   else if (randomNumber >= rate0 + rate1
     && randomNumber <= rate0 + rate1 + rate2)
   {
    return 2;
   }
   else if (randomNumber >= rate0 + rate1 + rate2
     && randomNumber <= rate0 + rate1 + rate2 + rate3)
   {
    return 3;
   }
   else if (randomNumber >= rate0 + rate1 + rate2 + rate3
     && randomNumber <= rate0 + rate1 + rate2 + rate3 + rate4)
   {
    return 4;
   }
   else if (randomNumber >= rate0 + rate1 + rate2 + rate3 + rate4
     && randomNumber <= rate0 + rate1 + rate2 + rate3 + rate4
       + rate5)
   {
    return 5;
   }
   return -1;
  }

  /**
   * 测试主程序
      * @param agrs
      */
  public static void main(String[] agrs)
  {
   int i = 0;
   MathRandom a = new MathRandom();
   for (i = 0; i <= 100; i++)//打印100个测试概率的准确性
   {
    System.out.println(a.PercentageRandom());
   }
  }
 }

转载于:https://www.cnblogs.com/muyuge/p/6152336.html