NotesApp.java

package JavaNotesApp;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;

public class NotesApp {
    private static final String FILE_NAME = "JavaNotesApp/notes.txt";

    private static Scanner sc = new Scanner(System.in);

    private static void addNote() {
        System.out.println("Enter your note (type 'END' on a new line to finish): ");
        StringBuilder note = new StringBuilder();
        String line;
        while (!(line = sc.nextLine()).trim().equals("END")) {
            note.append(line).append(System.lineSeparator());
        }

        try (FileWriter writer = new FileWriter(FILE_NAME, true)) {
            writer.write(note.toString());
            System.out.println("Note added successfully.");
        } catch (IOException e) {
            System.out.println("An error occurred while writing to file!");
            e.printStackTrace();
        }
    }

    private static void viewNotes() {
        try (BufferedReader reader = new BufferedReader(new FileReader(FILE_NAME))) {
            String line;
            System.out.println("--- Your Notes ---");
            while ((line = reader.readLine()) != null) {
                System.out.println(" - " + line);
                
            }
        } catch (FileNotFoundException e) {
            System.out.println("No notes found. add some first!");
        } catch (IOException e) {
            System.out.println("An error occurred while reading the file!");
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        boolean exit = false;
        System.out.println("<--- Java File I/O - Notes App --->");

        while (!exit) {
            System.out.println("Select an option to perform task.");
            System.out.println("1. Add Note");
            System.out.println("2. View Notes");
            System.out.println("3. Exit");

            System.out.print("Enter your choice---: ");

            if (sc.hasNextInt()) {
                int choice = sc.nextInt();
                sc.nextLine();

                switch (choice) {
                    case 1:
                        addNote();
                        break;
                    case 2:
                        viewNotes();
                        break;
                    case 3:
                        System.out.println("Exiting from the app.");
                        exit =  true;
                        break;                
                    default:
                        System.out.println("Invalid choice, Please select a valid option!");
                        break;
                }
                System.out.println("-----------------------------------------");
            } else {
                System.out.println("Invalid input, Please enter a number!");
                sc.nextLine();
            }

        }
    }

}