CODEWITHSUNDEEP
androidandroid-fragments
Neeraja Gandla
Neeraja Gandla

Reputation: 117

Will a fragment be destroyed if setRetainInstance(true) is not called?

I'm following Advanced android development training by Google. Here is the link. I came across this: Added a static fragment in xml

And on rotating the device, the selected radio button's state is retained as shown here:landscape mode

How is the fragment's state retained without using setRetainInstance(true)? Is the fragment not supposed to be destroyed along with the activity's onDestroy() method? If it is retained without explicitly calling setRetainInstance(true), what's the point of using the method? I'm confused with these two concepts. Can someone shed some light on this?

Upvotes: 2

Views: 94

Answers (1)

CommonsWare
CommonsWare

Reputation: 1006744

How is the fragment's state retained without using setRetainInstance(true)?

Obvious user-mutable state of widgets is usually put into the saved instance state Bundle automatically. This includes things like the text in an EditText widget and the checked state of CompoundButton implementations, such as a RadioButton.

Is the fragment not supposed to be destroyed along with the activity's onDestroy() method?

Yes.

If it is retained without explicitly calling setRetainInstance(true), what's the point of using the method?

In modern Android app development, you would not use it, preferring to use the ViewModel system instead. It, under the covers, uses setRetainInstance(true).

More generally, the point of retaining a fragment is for retaining state other than the obviously user-mutable state of widgets. For example, you might have some properties referencing business objects (e.g., an invoice, a customer) that you wanted to hold onto across the configuration change.

Upvotes: 2

Related Questions