Students

Create class Student which includes fields for name, course, weeks and
personal "counting" number that increases in order (1,2,3,…).
Methods for class Student:
- Constructor, which gets the name and course of student
- Accessors, which returns the values of fields
- Method, which sets personal number. Method will not set new number, if number is already given.
- Method, which is used to change the course of student.
- Method, which is used to increase amount of credit units.
- Method, which returns given information(s) of chosen student(s)

To handle all the students, class called Course has to be created. This database (java.util.Vector or java.util.Hashtable) stores all the information of students.
This class includes following methods:
- void addPupil( Student student ) :
  adds new student into database and gives it counting number.
- Student[] allPupils() :
  returns all the students who belongs to course.
- Student getPupil( Object oNumber ) :
  returns the information of given number/student or shows proper warning,
  if nothing is found.
- void HasGraduated( Object oNumber ) :
  removes graduated student from database
- printing method,
  which lists all the students and their numbers
Furthermore, you need to create a code for testing these classes/methods.