public void showNote(int noteNumber)
    {
        Note variable = notes.get(noteNumber);
        if(noteNumber < 0) {
            // This is not a valid note number, so do nothing.
        }
        else if(noteNumber < numberOfNotes()) {
            // This is a valid note number, so we can print it.
            System.out.println(notes.get(noteNumber));
            System.out.println(notes.getTitle());
            System.out.println(notes.getMessage());
        }
        else {
            // This is not a valid note number, so do nothing.
        }
    }