android mapFragment nullpointer exception-CodePudding

I am implementing an app which uses GPS Location data , with a mapFragment integration. Inside the fragment, i am instantiating the mapFragment as this:

val mapFragment =
    childFragmentManager.findFragmentById(com.example.sensorsapp.R.id.map_fragment) as com.google.android.gms.maps.MapFragment?
mapFragment!!.getMapAsync(this)

I am getting the exception mentioned bellow:

java.lang.NullPointerException
        at com.example.sensorsapp.Fragments.MapFragment.fetchLocation$lambda-1

For some reason it fails to initialize the map object. What is the reason for this?

CodePudding user response：

Cast the map fragment to SupportMapFragment instead of MapFragment and make sure you retrieve the mapFragment in onCreateView or onViewCreated()

val mapFragment =
    childFragmentManager.findFragmentById(com.example.sensorsapp.R.id.map_fragment) as SupportMapFragment?
mapFragment?.let{it.getMapAsync(this)}

CodePudding user response：

More code from the application:

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    fetchLocation()
}

fetchLocation() is the function where the mapFragment is instantiated.

Within the activity layout, the framelayout that contains the fragment:

<FrameLayout
    android:id="@ id/fragmentFrameLayout"
    android:layout_width="0dp"
    android:layout_height="0dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@ id/buttonActionRelLayout">

    <fragment
        android:id="@ id/map_fragment"
        android:name="com.google.android.gms.maps.MapFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</FrameLayout>