Application of Programming in Java Project

Please make some change with my code(see attachment) to follow these question below.
**MOST PART OF THESE PROJECT ARE SAME, JUST DO SOME MODIFY**
Task 1, Value: 8 marks
In this task, you are required to provide the definition of a class called Student, which represents a typical (but limited) university student.Each student has a name (which consists of a string of characters – for example: Janet May or Neil Kirby), a unique student identification (ID) number (consisting of a string of exactly seven numerical digits – for example: 1167895 or 8880123) and a course they are enrolled in (consisting of exactly three uppercase alphabetic characters – for example: MIT or BIT).
You are also required to define a class called TestStudent, which will be used to perform a number of test used to among other things, verify the correctness of the Student class.
In order to maintain the uniqueness of the student ID, your program will need to check that any new IDs supplied by the user is not the same as any of the existing student IDs. The program should also ensure that the student IDs and course names conform to the format specified above.
Following area list of specifications of the Student class:
Two fields name,id and course representing the student name, student ID and course respectively as described above
Get and set methods for each field (getName(), getId(),getCourse(),setName(), setId(), setCourse())
A toString() method that returns a string description of a given student object
An isValidId() method which accepts a string representing a possible new student ID as an argument and returns a boolean value (true or false) indicating whether the new ID satisfies the structural requirements of the student ID or not
A idExists() which accepts a string argument representing a possible new student ID and returns a boolean value indicating whether the new ID is already being used by another student or not
An isValidCourse() method which accepts a string representing a possible new course as an argument and returns a boolean value (true or false) indicating whether the new course name satisfies the structural requirements of the course or not
Your TestStudent class should be able to perform the following functions:
Create an ArrayList object of Student objects called studentList, using the student data stored in a text file named students.txt (you should create this file such that it stores the student name, ID and course of several students initially – one line per student)
Allow the user to add as many new Student objects as the user requests to the ArrayList ensuring that each student has a unique student ID
When the user has finished adding new students to the list, the program will override the students.txt file such that it includes the data relating to the new students as well as the original ones
Ability to display a full list of students as well as just the existing student IDs when necessary
Ensure that the program is appropriately documented throughout and thoroughly tested to demonstrate its correct operation.
Task 2, Value: 12 marks
In this task, you are required to provide complete class definitions and then create instances of various classes and use methods to perform various tests.
(a) Define an abstract class called Staff with the following fields and methods:
Fields: name, id, status representing the name, staff id and the status (full, part or casual) of a staff member in an organisation. Encapsulation should be used to protect these fields against intentional or accidental, direct modification
Constructors: a no-args/default constructor, and an overloaded constructor to initialise the fields to appropriate values when the instances of the class are created
Methods: a toString() method to print a string representation of the objects, get and set methods to provide access to each of the three fields
(b) Define a subclass of the Staff class called FullTimeStaff with the following additional field and methods:
Field: researchArea,a string variable representing the research are of the staff member. Again, encapsulation should be used to protect this field against intentional or accidental, direct modification
Constructors: a no-args/default constructor, and an overloaded constructor to initialise the fields to appropriate values when the instances of the class are created
Methods: a toString() method to print a string representation of the objects, additional get and set methods as required to provide access to the field
(c) Define a subclass of the Staff class called PartTimeStaff with the following additional field and methods:
Field: timeFraction representing the time fraction of a part-time staff member. This would be a number between 0.1 and 1.0. Again, encapsulation should be used to protect this field against intentional or accidental, direct modification
Constructors: a no-args/default constructor, and an overloaded construct