I have an activity with 3 fragments. Every fragment has a question.
When i create the activity I'm calling .add(...) method for the first fragment. For the others i call .replace(...) method with addToBackStack(...) method.
So i have this situation in the backstack:
.add(Frag1)
--> Frag 1
.replace(..., Frag2, ...)
-->Frag2
-->Frag1
.replace(..., Frag3, ...)
--> Frag3
--> Frag2
--> Frag1
Now, when I'm at the third fragment and then go back I'm popping it from the stack. I want to preserve the third fragment so if i go back to the second and then go next to the third i want to have the question answered and not to call again another onCreate().
I want to create a sort of switch of the fragments. Is it possible? Can someone help me?
You can create a fragment once and Show/Hide it depending on your needs.
See hide & show from FragmentTransaction docs
Also see this question
How about you use viewpager instead, you will need to:
Disable paging by swipe, so you can change the page programmatically
Load all pages at once (set setOffscreenPageLimit your pages count), so that each page keeps its state
Related
I have a Navigation panel activity. With 5 fragments (Will name it as Fragment1, Fragment2, ...) in menu sections.
Now by Default, activity will display Fragment1.
If user navigate to Fragmentxtz from Fragment1. We will add the fragment on top of Fragment1.
Now user goes to background by pressing home button and open the app from tasks.
Now i know Fragmentxtz onStart will be called. But i see that Fragment1 onStart is also called.
Is this expected behavior ?
As you can see on Android Developers, your fragment will be called at onViewCreated().
https://developer.android.com/guide/components/fragments#Creating
The View has to be updated in case you changed the system language or something like that.
Providing a bit more context to what might be happening here.
If both of your fragments are added e.g. via FragmentTransaction.add() both of them will have onCreateView() called when the layout is restored for the user as Robert pointed out. From the system's point of view all of those fragments are relevant to the user and would be shown simultaneously.
If on the other hand you add fragments via FragmentTransaction.replace() only the topmost fragment on the back stack will receive the onCreateView() call. This can also be achieved by doing an add and remove of the old fragment. If you make this transaction reversible by the back stack after pressing the back button your previous fragment would receive the appropriate lifecycle callbacks.
Scenario: I have three fragments in ViewPager in activity.
Fragment One
FragmentTwo
FragmentThree
I noticed that switching from fragment one to three onPause() method is called
but when I switched from fragment one to two onPause is not called
Problem: I want to show some data in FragmentOne's TextView with a webservice on button click.I clicked that button and data is shown But I noticed when I switch from one to two and then come back to fragment one data is shown. I want to hide that data when I come back to one. Is there any callback . ?
You need to understand Viewpager first. viewpager creates fragment in advance before and keeps so that there is smooth flow when you switch, like if you are on Fragment 2. viewpager creates 1 and 3 and keeps.
and when you are on Fragment 3 it retains Fragment 1.
Anyways you can increase the limit of viewpager with this
viewPager.setOffscreenPageLimit(int num)
you can understand all the lifecylce of fragment in Viewpager by putting Logs in onPause and onResume in viewpager fragments.
Anyways coming back to your prob. you need to have custom interface like this . answer helped me too
Its happening because Fragment One is in backstack. Dont keep FragmentOne in backstack while switching to FragmentTwo and on Back press of FrgamentTwo call switchContent for FragmentOne again .
I have developed project using Fragments and Tabs at Bottom,
I use just one activity and all fragemnts and tab click is managed by tabHost and stack of fragment
I use this code github link fragment_tab_study for setting tabs and maintaining stack of fragment
Now the issue is that we just push fragment(i.e replace fragment) so every time it call its onCreateView and all other method, I think this is a very big issue in this demo, as we click second time on tab1 it should only call its onResume method as happen in activity
is any solution for this ?
If you use replace of then in any case you have to start with onCreateView. If you dont want to recycle you can choose add method of transaction. But to replace is better in fragment terminology. You can even save transaction between fragment in back stack.
Please let me know if you have some other concern regarding fragment.
Thanks
Ankur
I asked this question before getChildFragmentManager() and viewpager without any responses, probably because the explanation was too long.
Simply put I have a viewpager inside a fragment. The pages inside that viewpager need to be replaced through a series of screens. Pressing back on those screens will not exit the application. How do I do this?
challenges:
viewpager xml does not use framelayout. when I use the replace method, what container
id do I use?
when replacing the fragments why would I use getChildFragmentManager each time if that is private to the current fragment?
#goonedroid: that's not the case I'm looking for here. The only similarity is that the fragment has a viewpager. My viewpager's pages need to be replaced when clicked:
I have a navdrawer. Clicking item 2 shows FragmentA. Clicking FragmentA replaces it with FragmentB. Clicking FragmentB replaces it with FragmentC. Clicking FragmentC takes you back to FragmentB. Fragments are added to the backstack for proper back navigation.
Clicking item 1 in the navdrawer shows FragmentZ with a viewpager. The viewpagers pages are just FragmentA and all the aforementioned behavior. But going from A to B here, then pressing back shows no pages in the viewpager.
I finally figured out a solution, not sure why this works because I thought an Activity's getSupportFragmentManager() returns the same fragment manager as its fragment's getFragmentManager().
Anyway, instead of getFragmentManager() in the fragments, use getActivity().getFragmentManager()
Scenario:
I have a fragment which has a ViewPager which contains 5 instances(different) of a single Fragment with different values, each having a listivew that contains some sort of items.
Problem:
The flow goes smooth when I click an item of listView(say on page1) but the moment I come back from there on pressing back (overridden OnBackPressed in the main_activity (will discuss later)), the viewPager fails to load the subFragments.
But when I switch to the 2nd or 3rd page, it gets displayed, and on going back to 1st page, it now gets displayed.
OnBackPressed():
I am maintaining a manual stack here. When I click on an item of ListView, the current Fragment Instance (of the parent Fragment ofcourse) goes into stack. And when user comes back , that instance gets popped off the stack and I replaces it on the activities FrameLayout container.
References:
Fragments not getting recreated by FragmentStatePagerAdapter after coming back to the main Fragment instance
Guys, I am really pissed off here, please help me out.
Frankly, I haven't worked much with fragments.
But it seems like the page is being thrown off the memory every time you switch to other pages. I am not sure but if there is a way for android to manage this and keep the page in its memory persistently, it might solve the problem
Finally I am able to get a workaround for this issue, which included two things:
while replacing the fragment make a call to
ft.replace(R.id.content_frame, frag).addToBackStack(null);
while initiating the ViewPager, the fragment manager to be used is :
mAdapter = new myAdapter(getChildFragmentManager());
Actually the problem is that, android fails to recognise and load the older instance of the fragment unless you explicitly add that instance to the backstack. So after adding it to BackStack, there is practically no need to maintain your own manual Stack, but you still can do that.