FileManager.java

import java.io.*;
import java.time.LocalDate;
import java.util.*;

public class FileManager {

    public static void saveSessions(List<StudySession> sessions) {
        try (BufferedWriter writer = new BufferedWriter(new FileWriter("sessions.txt"))) {
            for (StudySession s : sessions) {
                writer.write(s.getId() + "," + s.getSubject() + "," + s.getDurationSeconds() + "," + s.getDate());
                writer.newLine();
            }
        } catch (IOException e) {
            System.out.println("Error saving data.");
        }
    }

    public static List<StudySession> loadSessions() {
        List<StudySession> sessions = new ArrayList<>();

        try (BufferedReader reader = new BufferedReader(new FileReader("sessions.txt"))) {
            String line;
            while ((line = reader.readLine()) != null) {
                String[] parts = line.split(",");
                sessions.add(new StudySession(
                        Integer.parseInt(parts[0]),
                        parts[1],
                        Integer.parseInt(parts[2]), // seconds
                        LocalDate.parse(parts[3])
                ));
            }
        } catch (IOException e) {
            System.out.println("No previous data found.");
        }

        return sessions;
    }
}