1) Change array to ArrayList to store students in public class Course and change public class TestCourse accordingly.
2) Implement the dropStudent method (for option 2, see below).
3) Add a new method named clear() that removes all students from the course (for option 3, see below).
4) Modify your test program that creates two courses, adds three students and two students to each course respectively, removes one student from a course, and displays the students in each of the courses. Test it also to remove all students from a course and show number of students afterwards. (for option 1, 2, 3, see below).