Android kotlin.TypeCastException: null cannot be cast to non-null type com.google.android.gms.maps.SupportMapFragment

Question

I'm trying to code my current app in Kotlin, but I get null cannot be casted to non-null type. I've tried a lot of different stuff, but I keep getting the same problem. Not sure what to do. Any help would be appreciated!

Code:

class MapsActivity : AppCompatActivity(), OnMapReadyCallback {

private lateinit var mMap: GoogleMap
private lateinit var button: Button

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_maps)

    val mapFragment = supportFragmentManager
            .findFragmentById(R.id.mapFragment) as SupportMapFragment
    mapFragment.getMapAsync(this)
}

override fun onMapReady(googleMap: GoogleMap) {
    mMap = googleMap;
    setUpMap();
}

fun setUpMap() {

    val et = findViewById<EditText>(R.id.editText);
    val et2 = findViewById<EditText>(R.id.editText2);
    val lat = et.getText().toString().toDouble();
    val lng = et2.getText().toString().toDouble();
    //val ll = LatLng(lat, lng)

    button = findViewById(R.id.button) as Button
    button.setOnClickListener {
        goToLocation(lat, lng, 11.0f);
    }
}

fun goToLocation(lat:Double, lng:Double, zoom:Float) {
    val ll = LatLng(lat, lng);
    val update = CameraUpdateFactory.newLatLngZoom(ll, zoom);
    mMap.addMarker(MarkerOptions().position(ll).title("Marquette, Michigan"))
    mMap.moveCamera(update);
}

XML:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="16dp"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:paddingTop="16dp"
tools:layout="@layout/activity_maps">

<EditText
    android:id="@+id/editText"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPersonName" />

<EditText
    android:id="@+id/editText2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPersonName" />

<Button
    android:id="@+id/button"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Submit"/>
    <!-- android:onClick="locate"/> -->

<fragment
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:name="com.google.android.gms.maps.SupportMapFragment"
    android:id="@+id/mapFragment"
    />

Logs:

Caused by: kotlin.TypeCastException: null cannot be cast to non-null type com.google.android.gms.maps.SupportMapFragment at com.example.nrice.mapsproject.MapsActivity.onCreate(MapsActivity.kt:38)

Answer 1

if you are using SupportMapFragment in a Fragment you have to write "childFragmentManager.findFragmentById(R.id.myMap)" statement in

override fun onViewCreated(view: View, savedInstanceState: Bundle?)

not in

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View?