编写程序计算三门课的平均成绩，要求应用程序分别用Java语言三种不同的循环语句实现，每门课的成绩用Math类的random()方法

随机产生（random()产生的数值在0和1之间），成绩范围为40~100。 -Write a program grade point average calculation of three lessons to require the application were used Java language in three different loop realization of the achievements of each course with the Math class, random () method of randomly generated (random () produces values between 0 and between 1), results range from 40 ~ 100.