It seems like we're discussing this in the abstract, as common
functionality can mean a lot of different things.
Given that Java doesn't have multiple inheritance (which in my opinion
is a good thing), the basic options I can think of are:
- A common base class;
- Delegation.
Having a common base class gets in the way of using Android-defined
Activity subclasses, however.... I can see MapActivity and
PreferenceActivity being useful, but not being able to use e.g.
{Expandable}ListActivity doesn't seem like a big loss.
Still, I prefer delegation in most cases. This lets you use multiple
helper objects if needed, whereas a common base class can provide only
one customization. Delegating a handful of most important lifecycle
methods isn't hard either.
Taking the base class approach with more than one base class
(MyActivity, MyMapActivity, MyPrefrenceActivity) raises the question of
how these classes would implement their common functionality and avoid
code duplication. The answer is most likely delegation, again.
A third option is code injection.
There are libraries for Android that use the common base class approach
(GreenDroid, IIRC), and code injection (can't remember the name right now).
-- Kostya
12.05.2011 23:03, Adam Ratana пишет:
It's not really pretty though and I'm curious what other approaches
have been used in the wild, to share some common functionality across
different Activity classes of different types; I feel this design can
be re-factored into something better and more scalable/maintainable.
For my purposes right now, it's fine, and I'm sure I will re-factor it
soon enough, when time and priorities allow. But curious what other
developers have done to share common code across different Activities
which are all derived from different parent classes. I'm making an
assumption that we're talking about common code that we want to
execute during activity lifecycle methods and activity related
methods?
--
Kostya Vasilyev -- http://kmansoft.wordpress.com
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