Hello there, please help me in Java. Please explain if possible with comments. Thank you very much.

You are given two .txt files. Employee.txt and Departments.txt.

Suppose you have already created the constructor and the files are read and all arrays are created. I need to create only methods.

1. Add a method named employeeNumber that accepts an integer index and returns the number of employees in that department.

2. Add a method named employeeRetrieval that accepts a String employee id and returns the first department index with that String employee id.

3. Add a method named employeesTotal that returns the number of all employees in all departments

4. Add a method named employeeAtDepartment that accepts an integer department index and an integer employee index and returns the employee at the specified department and employee index.

5. Add a method named departmentNumber that accepts a String department name and returns the number of employees in that department

6. Add a method named departmentTotal that accept an integer index and returns the department name.

Please only use Arrays, no bufferedReader, no ArrayList. Thank you very much