When to deregister a java/android object from another -
in oo think not uncommon object register object (perhaps singleton) callbacks.
in c++ think not uncommon registration in constructor or super class constructor of object being registered , deregistration destructor. gives assurances right timing.
i have 2 questions. best strategy achieve in java in general, given lack of destructor? in android, if object member of activity or fragment, guess object should registered , deregistered within 2 of on... methods in activity or fragment. think may hard know when object destroyed. 2 on... methods in activity or in fragment best use this?
additionally, perhaps less common, if object referenced number of other objects can 1 decide deregister on basis going out of scope , how or can 1 deregister based on other state implies on balance happy no longer receive call backs?