StudentManager.java

import java.util.ArrayList;
import java.io.*;

public class StudentManager{

    private ArrayList<Student> students = new ArrayList<>();

    public void addStudent(Student student){
        students.add(student);
        System.out.println("Student added successfully: " + student);
    }


    public void viewStudents(){
        if(students.isEmpty()){
            System.out.println("No students found.");
            return;
        }

        for(Student s : students){
            System.out.println(s);
        }
    }

    public void searchStudent(int id){

        for (Student s: students){

            if(s.getId()== id){
                System.out.println("Student found: " + s);
                return;
            }
        }

        System.out.println("Student with ID " + id + " not found.");
    }

    public void deleteStudent(int id){
        students.removeIf(s -> s.getId() == id);
        System.out.println("Student with ID " + id + " deleted successfully.");
    }


    // Save all students to file 
public void saveToFile() {

    try {
        // FileWriter writes text into file
        BufferedWriter writer =
            new BufferedWriter(new FileWriter("students.txt"));

        // write each student line by line
        for (Student s : students) {
            writer.write(s.toFileString());
            writer.newLine();
        }

        writer.close();

    } catch (IOException e) {
        System.out.println("Error saving file.");
    }


}


// Load students from file when program starts
public void loadFromFile() {

    try {
        BufferedReader reader =
            new BufferedReader(new FileReader("students.txt"));

        String line;

        // read file line by line
        while ((line = reader.readLine()) != null) {

            // split text using comma
            String[] data = line.split(",");

            int id = Integer.parseInt(data[0]);
            String name = data[1];
            int age = Integer.parseInt(data[2]);
            String course = data[3];

            // recreate Student object
            students.add(new Student(id, name, age, course));
        }

        reader.close();

    } catch (IOException e) {
        System.out.println("No previous data found.");
    }
}
}