Hello, help me understand how to write those methods in JAVA. (Please don't use bufferedreader)

Write a patient management program. You have two .txt files:

- Patient.txt with id, names and the doctor they are seeing (e.g. 123, John Doe, Jason Smith)

- Doctors.txt with the doctors name and the Doctor's id (e.g. Jason Smith, JS1) , (Linda Hernandez, LH1)

Write the following methods:

1) Get the count of the Doctors.

+getDoctorCount() :Integer

2) Get the number of patients with the same Doctor by index

+getPatientCount(doctorIndex: Integer) : Integer

3) Get the number of the patients from all Doctors.

+getPatientCount() : Integer

4) Get the number of patients with the specified Doctor.

+getPatientCount(doctorName: String) : Integer

5) Get the Doctors Name at a specific index.

+getDoctorsName(doctorIndex: Integer) : String

6) Get the patient name with a specific Doctor and the patient id

+getPatient(doctorIndex: Integer, patientIndex: Integer) : Patient

7) Get a copy of a patient array for the Doctor at the specified index

+getPatients(doctorIndex: Integer) : Patient[ ]

8) Get the first Doctor index thats matches the specified patient id.

+findPatientDoctor(id: String) : Integer

Thank you.