问题
There are few similar questions on stackoverlow, but I haven't find clear explanation at any of the answers how to implement Action Bar pattern for more complex/multiple activities apps.
As I understand, there are two options to do this:
1.) implement multiple activities and in each of them implement/include action bar --> problem with this is that when ever you lunch new activity, although it has the same looking action bar, it has that transition, and jumps through the screen, so it's obvious it's a new "window",new separate screen, and it kills that feeling of single app navigation frame.
2.) Use single FragmentActivity, with action bar within, and with multiple fragments that inflate content frame. --> this is pretty nice implementation of action bar pattern, but problem is that it goes against google's recommendation that one fragment should be in one activity in the case of phone. Or it doesn't? From the "look and feel" I would say that Gmail app is done mostly this way.
3.) TabActivity - which is deprecated.
For the second solution (single activity, multiple fragments) I'm concerned if there would be any performance issue in the future? How does android handle memory in that case? will it kill inactive fragments to free space just like it does with the activities? Or it will kill the whole app, or user phone will be overloaded?
Maybe I'm missing something there, but I found implementing android navigation patterns and usage of fragments very confusing :/
Is there any reason against having one activity with multiple fragments on the phone? (there would be cca 5-6 fragments, with nested fragments in some of them)
回答1:
First of all, you might think this question and this answer to be useful.
Though you are talking about the actionbar, the real question is about the pattern of ONE activity with multiple fragments or MULTIPLE activities. As the former link states, though the "oversimplified tutorial" suggests of starting another activity to display item's content in Phone situation, this will probably cause some duplicated logic or codes.
Finally, using "FragmentActivity with multiple fragments" is recommended. As it is against the the google's recommendation, Stephen Asherson says and I quote: " do not think of it as being forced to use many activities. Think of it as having the opportunity to split your code into many fragments, and saving memory when using them".
PS. just for your information, if you change the activity's actionbar in switching fragments, you might want to do something to correctly handle the UI change when "back" key is pressed and backstack is changed. Commonly, override the onbackstackchanged() function to handle the UI.
来源：https://stackoverflow.com/questions/18820173/android-actionbar-pattern-multiple-activities-or-fragments