OnActivityResult not called when nested fragment is using replace instead of add with Don't Keep Activity

Question

I created a simple App below with

MainActivity -> ContainerFragment -> MainFragment

The ContainerFragment uses replace to commit the MainFragment.

I turn ON doesn't keep Activity`

When MainFragment call startActivityForResult, and return from the activity, the onActivityResult is not called.

This doesn't happen when

• It is a single Fragment. (not nested)
• Don't Keep Activity is OFF
• When ContainerFragment uses add to commit the MainFragment.

To replicate the problem, download the code in the following github and run it. (Remember to turn on Don't Keep Activity). Click Start Activity.., and then click End Activity and expect a Toast (no Toast, shows that the onActivityResult in the fragment is not called)

https://github.com/elye/issue_android_onactivityresult_not_called

Apparently there was previously a reported nested Fragment can't get onActivityResult in the past as posted in https://stackoverflow.com/a/36239436/3286489, but stated has been resolved in Android Support Library 23.2.1. But for my case, I tried on Android Support Library 28 (Android Pie). So this is still a valid issue I believe.

Share it here in case I am wrong, and there's some explanation to this out there.

In case workaround, there's one recommended in https://inthecheesefactory.com/blog/how-to-fix-nested-fragment-onactivityresult-issue/en.

Another workaround as reported in https://stackoverflow.com/a/20543245/3286489

Answer 1

Based on the answer from https://issuetracker.google.com/issues/36926548, it solved the problem.

The reason is before the Fragment is created, we should check that savedStateInstace is null first.

In this case in the project of https://github.com/elye/issue_android_onactivityresult_not_called,

the ContainerFragment it should be

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    if (savedInstanceState == null)
        childFragmentManager.beginTransaction().replace(R.id.fragment_container, MainFragment()).commit()
}

And in MainActivity, it should be

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    if (savedInstanceState == null)
        supportFragmentManager.beginTransaction().add(R.id.container, ContainerFragment()).commit()
}