output not needed but please the code first

Create a three different java classes Student, Marks and Grade with necessary attributes and methods. Write a Test main class which gets the following i given expected output conditions. Get student name, regno, noofsubjects and its marks. Functional requirements of the classes: 1. Student class should hold name, regno. 2. If the student class have null values in name or regno, it should through a NullPointerException 3. Marks class should store all the subject marks and if any mark is negative values or more than 100, it should through a user defined exception messag 4. If the number of subject is less than 1, grade class should through an ArithmeticException 5. Grade class should find the grade based on the following conditions If average of mark is >= 90 - A grade If average of mark is >= 80 and = 70 and