Things are progressing well with AudioMan but I'm going slowly making sure I don't miss any tests. I've also cleaned up a lot of the APIs for the repository and file packages that had gathered cruft.

I'm starting on the controller part of the program now. If you remember the diagram from a few days ago, the controller is told by the GUI what to put in the models, which are in turn displayed by the GUI. So the controller controls what goes in the models and that's what the GUI displays (the view).

Remember when I was talking about updating the models from the mutators? Well this didn't make much sense. The controller updates the model, so the mutator should tell the controller something happened and then the controller will respond to that.

So far in the controller I've invented an object called TrackFilter based on the FilenameFilter interface in the Java libraries. As an aside, it's useful to read about these libraries because they can give you good ideas for your own programs. Anyway, the TrackFilter constructor takes three parameters: playlist, artist and album. It also has a method named boolean accept(AudioData), which takes a track as input and decides whether or not it matches the criteria given in the constructor.

So for example, if the GUI wants to display all of the Ricky Martin *cough* songs I have in my entire collection, I'll make this object:

TrackFilter tfRicky = new TrackFilter(IRepository.COLLECTION, "Ricky Martin", null);

and pass it to the controller. The first parameter is the playlist, in this case the whole collection (as a constant). The second parameter is the artist and the third is the album (where null is "all").

The first thing the controller will do is clear the artist, album and track models. Then it will ask the repository for all of the Ricky Martin tracks in the collection and add them one by one to the models.

So let's say I want to add another Ricky Martin track while the view is already displaying Ricky Martin tracks. The view needs to be updated by the models which are updated by the controller to show this new track. The mutator, which does additions and removals from the collection, will tell the controller that a new track has been added. The controller then uses the boolean accept(AudioData) method that was passed to it to determine whether or not the models should be notified about that new track being added. If so, it adds the track to the models.

So while a view it being displayed it doesn't have to be completely reloaded if an addition or removal occurs. If the track passes the controller's filter it will be added to the models and appear in the user interface.