Although the behavior of the IPreferenceStore provided by AbstractUIPlugin#getPreferenceStore()
hasn't changed we have updated the specification of IPreferenceStore
to explicitly define the behavior that we have provided.
Typing of PropertyChangeEvents
Any property change event from an IPreferenceStore must have an old and new value of the same type that is consistent with the setValue call that generated it.
For instance if you call IPreferenceStore#setValue(String name, long
value) the values in the PropertyChangeEvent generated from this method
will both be of type java.lang.Long.
putValue
Calls to #putValue will not generate a PropertyChangedEvent.
Calls to the various #setValue methods will.
Relationship between the OSGI Preference and an IPreferenceStore
The IPreferenceStore provided by AbstractUIPlugin#getPreferenceStore()is
an instance of ScopedPreferenceStore which uses org.osgi.service.prefs.Preferences
as a back end. org.osgi.service.prefs.Preferences propagates change
events as Strings only.
The ScopedPreferenceStore wrappers those OSGI events generated
by IPreferenceStore#setValue(String name, String value) and one
of it's own PropertyChangeEvents and forwards that event to it's
listeners. For the other implementations of IPreferenceStore#setValue
the ScopedPreferenceStore will create it's own events of the correct
type and not propagate the events from the OSGI preferences.
Listeners to a ScopedPreferenceStore should be prepared for both typed
and String values in thier change events as it is still possible to get an event
via the OSGI preferences (during a preference import for instance). OSGI events
are always of type java.lang.String.