Getting AM/PM information from LocalDateTime instance

Nick :

I am taking time input from user as a String in Java and then converting it to LocalDateTime object and saving it in a text file.

Problem

hh:mm a is the format in which i am taking input form user. If i enter 12:30 PM, it is saved in text file with current date as 2019-03-20T12:30 without indication of AM or PM.

Consequently, when i read it from text file, i get the date-time information without AM or PM.

Question

Why is AM or PM not saved in the text file and how can i get it from LocalDateTime instance?

Code

Following method takes input from user, converts the user input in to LocalDateTime instance and returns it which is then saved to text file as a String

private static LocalDateTime getTimeInput(String question) {        
    System.out.print(question);
    String userInput = scanner.nextLine();

    userInput = AppointmentManager.validateTimeString(userInput, question);

    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd h:m a");
    String todaysDateString = LocalDate.now().toString();
    userInput = todaysDateString + " " + userInput;

    return LocalDateTime.parse(userInput, formatter);       
}

validateTimeString function is used to verify that user input is in correct format

Following method saves the data to text file

private static final File file = new File("appointments_data.txt");

public static void saveAppointmentInfo(Appointment appointment, boolean appendToFile) {     
    try (FileWriter fw = new FileWriter(file, appendToFile);
        BufferedWriter bfw = new BufferedWriter(fw)) {

        String str = AppointmentDataManager.getAppointmentInfoAsString(appointment);

        bfw.write(str);
        bfw.newLine();

    } catch (IOException ex) {
        ex.printStackTrace();
    }
}

getAppointmentInfoAsString method

private static String getAppointmentInfoAsString(Appointment appointment) {
    StringBuilder sb = new StringBuilder();

    sb.append(appointment.getPatientId())
       .append(";")
       .append(appointment.getStartTime())
       .append(";")
       .append(appointment.getEndTime())
       .append(";")
       .append(appointment.getDoctor().getName());

    return sb.toString();
}

Karol Dowbecki :

When you are using StringBuilder you are calling LocalDateTime.toString() when the String segment is appended. As per LocalDateTime.toString() method javadoc:

The output will be one of the following ISO-8601 formats:

• uuuu-MM-dd'T'HH:mm
• uuuu-MM-dd'T'HH:mm:ss
• uuuu-MM-dd'T'HH:mm:ss.SSS
• uuuu-MM-dd'T'HH:mm:ss.SSSSSS
• uuuu-MM-dd'T'HH:mm:ss.SSSSSSSSS

You need to save LocalDateTime with custom format to get AM/PM:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd h:m a");

sb.append(appointment.getPatientId())
   .append(";")
   .append(appointment.getStartTime().format(formatter))
   .append(";")
   .append(appointment.getEndTime().format(formatter))
   .append(";")
   .append(appointment.getDoctor().getName());