Some fields in MediaTracker and its supporting classes can be marked as final: these fields never change after being initialised in the constructor for the class.

MediaTracker.target is the component associated with this instance of media tracker. The value is initialised in the MediaTracker constructor and is never changed.

MediaTracker.head can be private, it's not used outside of the class.

The fields `tracker` and `ID` in the MediaEntry class are never changed after being set in the constructor.

The fields in ImageMediaEntry—image, width and height—can also be final.