Android Fragment not showing after coming back after a while? - android

I have a sherlock activity(A) that contains a fragment(B) which again contains a tab and FragmentViewPager(C) which contains a Fragment (D).
I have a weird issue here.
Initially everything shows up fine.
If I close the app by pressing the home button, then come back immediately to the app, then everything is fine (A containing B containing C containing D)
However, if I close the app by pressing the home button, then work on other apps for a long time, then come back to my app, then I see A containing B containing C containing an empty screen.
Here are two questions.
1. Why doesn't the fragment D show up?
2. It seems like something is wrong with onResume() or something in D? Or is it related to process issue? Lifecycle? How can I fix that?
3. In order to recreate the issue, I have to close the app, then spend a lot of time playing other apps. Is there a way to recreate this issue quickly without having to waste time?
Thanks a lot...

Related

Activity is destroyed when hit home button (only on Pixel3)

I have one big and long question
I have one activity with 4 fragments using viewPager.
the first fragment also has 4 fragments using viewPager
the second fragment has 6 fragments using general fragment way (replace or add on framelayout)
Here are my question and problem
For example, I am in the first tab and in the second fragments, then hit homebutton and then bring my app upfront. after that suddenly all functionalities are not working. the back button is not working. the button in the fragment is not working. (error log said the fragment is not attatched)
it happens only on pixel3.
I have 5 different android phones but working fine on those phones.
I thought it could be the memory issue, so I turned on "profiler" from Android Studio, and I saw the weird thing. only pixel3 when I pressed the home button the activity is destroyed. I tested all other phones with "Profiler" the activity's state is saved not destroyed.
Does anyone have the idea of why it happened and fixed the problem?
Are the embedded fragments problem? or is it OS10 problem?
I found the issue. there is one option in developer mode named "Don't keep activities". that was on, that is why my app is working differently on pixel3.

How to switch between different activities like tabs in android?

I need to develop an application which contain these tabs shown in the image. Each tab contain a form which will be filled by the user.User can switch to any tab.
User click Activity1, Activity 1 gets displayed and user enters some data; then user press Activity 2, activity 2 gets displayed, user press Activity1 again, Activity 1 gets displayed with the data entered by the user(not the blank activity).
At the end when user click "Save" I need to get all the data from these activities and save it somewhere.
I have worked a lot in java but new to android, I am stuck in developing the UI for this scenario. However I have done this many times in iOS.
Anybody please share your experience of developing such UI.
Thanks,
Fragments will be more suitable for this scenario, the benefit are
They are light weight and faster
Managed automatically by the FragmentManager.
Data Sharing between Fragments is smoother and simpler than it is for Activities
They don't complicate the Architecture of the Application
You can have as many Fragments as you want in you Activity. Following two links can be useful for you.
A similar Thread
A Good Tutorial
Another good tutorial
If even after that you decide to use Activities, You need to think

Android Ghost Layout on Activity Transition

I noticed something strange today and i'm not sure the best way to describe it.
I have two activities (A and B). I'm on A and start a new intent for B. I override the pending transition to be a slow slide up. This part is fine.
When B is sliding up I noticed that I can still tap on the screen where B's buttons would be and use their actions. (example, there is a close button to close B. When I tap on it's destination area it will close B even though it hasn't completely gone up).
My current solution is to disable all of the buttons until the animation is done. This is working fine, however I'd be interested to know if there is a better (more standard) solution. If anyone can explain (and confirm my suspicions) then that'd be a nice plus!
This is the expected behavior. Android is simply animating a transition and not actually moving the views from one physical location to another.

FragmentActivity with ViewPager managing multiple fragments taking 2 back presses to exit

I have tried searching across to find a solution for it, but none of them seemed to work.
My use case is: I have a FragmentActivity which contains a ViewPager to manager couple of fragments whose that if coming from different data sources - thus things like Service,Content Proviers,Loaders etc are involved.
While the onCreateView of my Fragments is only called once, but when I try to exit the application by pressing the back key, the view pager first removes the fragment set and display the blank activity, and the consequent press on the back actually exits the application.
I have tried couple of things like:
calling finish() in onKey... onBackPressed within the activity
calling getActivity().finish() from withing the Fragment and its
main layout view
but none of them worked.
**closing application by using its PID - thats something I dont want to try.
Its surely not the standard behaviour becuase I have seen people on SO asking the opposite of my query with their apps getting exited.
So, I would really like the activity to be closed on the first press of the back button.

How to manage multiple Activity stacks in an Android app, like you would on iOS with multiple UINavigationControllers within a UITabBarController?

A fairly common model for iOS apps seems to have a single UITabBarController, where each tab essentially holds a UINavigationController, i.e. a stack of controllers, and pressing a tab switches to the top of the corresponding stack. Can I get the same behavior on Android without a lot of custom code? (Note: I am using menus instead of tabs on Android).
After reading http://developer.android.com/guide/topics/fundamentals/tasks-and-back-stack.html the closest I can see is to have multiple tasks, each one representing a stack (akin to UINavigationController), and to use FLAG_ACTIVITY_NEW_TASK to switch to another task/stack. When I switch, is there a way to go straight to the top of the stack, or do I need to keep that piece of state myself?
One problem with keeping that state myself: I've noticed that if my app launches an Intent that starts a new process, sometimes my original app's process is killed (I think), and all of my global state is destroyed.
The only other solution I can imagine is to have a dummy Activity per stack, to push DummyActivityN essentially right before I switch away from the Nth stack, and, when switching to the Mth stack, to start activity DummyActivityM with FLAG_ACTIVITY_NEW_TASK, and then have DummyActivityM immediately finish() itself.
One last problem: as I navigate to the bottom of one of the stacks, with the back button, I would like to hit the back button once more and NOT go to another stack/task. But this seems easy to overcome by launching an Intent to go to the home screen; is there anything better?
If I understood your problem correctly, if you add this parameter to your Activity declarations in AndroidManifest.xml, the Activities that are launched by your custom menu will be only created once - keeping their state while you move around the tabs.
android:launchMode="singleTask"
I hope this helps,
Best,
-sekran

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