NoteManager.java

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

public class NoteManager {
    private static final String NOTES_DIR = "notes";

    public NoteManager() {
        File dir = new File(NOTES_DIR);
        if (!dir.exists()) {
            dir.mkdir();
        }
    }

    public void saveNote(String title, String content) throws IOException {
        if (title == null || title.trim().isEmpty()) return;
        File file = new File(NOTES_DIR, title + ".txt");
        try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
            writer.write(content);
        }
    }

    public String loadNote(String title) throws IOException {
        File file = new File(NOTES_DIR, title + ".txt");
        if (!file.exists()) return "";
        StringBuilder sb = new StringBuilder();
        try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
            String line;
            while ((line = reader.readLine()) != null) {
                sb.append(line).append("\n");
            }
        }
        return sb.toString();
    }

    public List<String> listNotes() {
        File dir = new File(NOTES_DIR);
        String[] files = dir.list((d, name) -> name.endsWith(".txt"));
        List<String> titles = new ArrayList<>();
        if (files != null) {
            for (String f : files) {
                titles.add(f.substring(0, f.length() - 4));
            }
        }
        return titles;
    }
}