Interpretor Pattern: Need Help

[Deepak Lal]

Hi,
I'm writing a Java sample program for demonstrating interpretor design Pattern.

-------------------------------------------------------------------------------------------
MusicalNotes
# Musical Notes Properties file
# This denotes the frequencies of musical notes in Hz
Sa=256
Re=288
Ga=320
--------------------------------------------------------------------------------------------

NotesInterpreter.java 
public class NotesInterpreter {
     private Note note; //-----> Note class

/**
* This method gets the note from the keys pressed.
* Them, this sets it at a global level.
*/
public void getNoteFromKeys(Note note) {
Frequency freq = getFrequency(note);
sendNote(freq);
}

/**
* This method gets the frequency for the note.
* Say, if the note is “Sa”, it will return 256.
*/
private Frequency getFrequency(Note note) {
// Get the frequency from properties
// file using ResourceBundle
// and return it.
return freq;
}

/**
* This method forwards the frequency to the
* sound producer which is some electronic instrument which
* plays the sound.
*/
private void sendNote(Frequency freq) {
NotesProducer producer = new NotesProducer();
producer.playSound(freq);
}
 
}// End of class 
---------------------------------------------------------------------------------------------
NotesProducer.java
public class NotesProducer {
   private Frequency freq; //----> Frequency class

public NotesProducer() {
this.freq = freq;
}

/**
* This method produces the sound wave of the
* frequency it gets.
*/
public void playSound(Frequency freq) {
      System.out.println("Playing the note of desired frequency ::"+freq);
} 
}// End of class 
--------------------------------------------------------------------------------------------

Can you please tell me how should i go about writing the "Note class and the Frequency class" for the above example.

How should i invoke the above class from my main method.I'm finding it difficult to proceed.
Need your help ??

Help provided will be appreciated.

--
Deepak Lal

[Ilja Preuss]

Where do you see the Interpreter design pattern in this example?

[Deepak Lal]

This is an example of Interpretor design pattern.
The musical notes along with their frequencies is stored in the properties file.
By passing a Note,a corresponding frequency is retrieved and based on the frequency a corresponding sound is produced.

Please see the below link for reference.
http://www.allapplabs.com/java_design_patterns/interpreter_pattern.htm.

Can you tell me how should my Note class and Frequency class Look like and how should i write a main method such that it invokes the class. ?

--
Deepak Lal