CODEWITHSUNDEEP
androidkotlin
dodododo97
dodododo97

Reputation: 165

KotlinNullPointerException when rotating the screen on Fragment with map and localization

I have a kotlin.KotlinNullPointerException at line:

val locationmanager=context!!.getSystemService(Context.LOCATION_SERVICE) as LocationManager

When I rotate my screen. This line is in function in:

class MyMapFragment: Fragment(),OnMapReadyCallback

Upvotes: 0

Views: 176

Answers (2)

Quinn
Quinn

Reputation: 9434

The activity is destroyed and re-created when you rotate the phone. This means while the activity is being re-created the context will be null, and you must be trying to access it at some point during this.

I'm not sure where you have the line of code you posted, but if you want to guarantee a non-null context you should wait till the activity is created.

var locationmanager: LocationManager? = null   

override fun onActivityCreated(savedInstanceState: Bundle?) {
    val context = context ?: return // this line gets a non-null context and is safer than !!

    locationmanager = context.getSystemService(Context.LOCATION_SERVICE) as LocationManager

    ...

In general, when accessing things that are nullable in Kotlin, it is much preferred to use ? instead of !! to avoid any null pointer exceptions

Upvotes: 1

Yrii Borodkin
Yrii Borodkin

Reputation: 782

Fragment can access context only after onAttach lifecycle method called, because it get attached to it's host activity in this lifecycle method. So, to avoid NPE you need in fragment 

lateinit var locationmanager: LocationManager

override fun onCreateView(inflater: LayoutInflater,
                          container: ViewGroup?,
                          savedInstanceState: Bundle?): View? {
    locationmanager = context!!.getSystemService(Context.LOCATION_SERVICE) as LocationManager
    return inflater.inflate(R.layout.your_fragment_layout, container, false)
}

Upvotes: 1

Related Questions