Problem to get Context in FragmentView Kotlin

Question

I need to get a Context from my activity. When i do that using:

   override fun getContext(): Context {

    return activity.applicationContext
}

i got:

safe ( .) or non-null asserted ( .) calls are allowed on a nullable receiver of type FragmentACtivity

activity is calling your fragment's getActivity() which isn't guaranteed to not be null. So you'll have to do activity!!.applicationContext!! — em_
– em_, Commented Jan 21, 2019 at 19:58
im calling this method from my Fragment... i think when that fragment are created, my activity is not null. Right? — Flávio Costa
– Flávio Costa, Commented Jan 21, 2019 at 20:01
There are scenarios in the life cycle of Android where the activity will be null during the instance of your Fragment. More often than not, activity will exist, but in this case Kotlin is forcing you to be smart about accessing it. A simple (but helpful) nuance of Kotlin — em_
– em_, Commented Jan 21, 2019 at 20:08
You are right man. Im newbie on Kotlin, i started on a few days ago. Thx dude. — Flávio Costa
– Flávio Costa, Commented Jan 21, 2019 at 20:19
No problem, a helpful approach to learning Kotlin in Android Studio is to click red errors (red squigglies under code) and use ALT+ENTER to get a solution to fix your problem - more often than not, it's Kotlin telling you to be hyper-conscious about nullability — em_
– em_, Commented Jan 21, 2019 at 20:23

em_ · Accepted Answer · 2019-01-21 20:21:49Z

2

For formality purposes, posting answer here

activity is calling your fragment's getActivity() which isn't guaranteed to not be null. So you'll have to do activity!!.applicationContext!!

There are scenarios in the life cycle of Android where the activity will be null during the instance of your Fragment. More often than not, activity will exist, but in this case Kotlin is forcing you to be smart about accessing it. A simple (but helpful) nuance of Kotlin

answered Jan 21, 2019 at 20:21

em_

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3 Comments

Ali Kazi Over a year ago

Is this the best we can do? Is there any other way to return a non null activity context? In my case I store the reference to a val in onCreate using activity!! then use that variable as my context reference.

Anton Kogan Over a year ago

Do like that and when activity will be null, you will have exception, as you said "There are scenarios in the life cycle of Android where the activity will be null during the instance of your Fragment" and then you call !! and get crash. Better way is use injection of context, or view context if available.

em_ Over a year ago

@AntonKogan injecting context is generally bad context. The nullability of context has been a part of the platform since it's existence and it's on the developer to use it correctly. Hence why requireActivity() requireApplication() requireContext() was brought in.

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