我正在尝试使用Google Maps API的信息框。尝试运行该应用程序并添加带有自定义信息框的标记时,它会崩溃。 这是我的代码:
MainMapsActivity类:AppCompatActivity(),OnMapReadyCallback {
private lateinit var mMap: GoogleMap
private val test: ArrayList<String> = arrayListOf()
private var mLocationPermissionGranted: Boolean = false
private val PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION: Int = 1234
// ^Number isnt definitive, as long as its unique inside the application
private val DEFAULT_ZOOM: Float = 15.0F
private var mLastKnownLocation: Location? = null
private val mDefaultLocation = LatLng(60.312491, 24.484248)
private lateinit var mFusedLocationProviderClient: FusedLocationProviderClient
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main_maps)
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
val mapFragment = supportFragmentManager
.findFragmentById(R.id.map) as SupportMapFragment
mapFragment.getMapAsync(this)
mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this)
}
override fun onMapReady(googleMap: GoogleMap) {
mMap = googleMap
getDeviceLocation()
//PRESSING WILL ADD MARKER
mMap.setOnMapClickListener(GoogleMap.OnMapClickListener { point ->
val builder: AlertDialog.Builder
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
builder = AlertDialog.Builder(this, android.R.style.Theme_Material_Dialog_Alert)
} else {
builder = AlertDialog.Builder(this)
}
val marker = MarkerOptions().position(point)
builder.setTitle("Are you sure you want to add a map location here?")
.setMessage("Are you sure you want to add a map location here?")
.setPositiveButton(android.R.string.yes, DialogInterface.OnClickListener { dialog, which ->
mMap.addMarker(marker)
//CUSTOM MARKER
.setIcon(BitmapDescriptorFactory.fromResource(R.mipmap.pinetree_foreground))
})
.setNegativeButton(android.R.string.no, DialogInterface.OnClickListener { dialog, which ->
// do nothing
})
.show()
true
val mapInfoWindowFragment = supportFragmentManager.findFragmentById(R.id.infoWindowMap) as MapInfoWindowFragment
//Set Custom InfoWindow
val infoWindow = InfoWindow(point, InfoWindow.MarkerSpecification(0, 0), mapInfoWindowFragment)
// Shows the InfoWindow or hides it if it is already opened.
mapInfoWindowFragment.infoWindowManager()?.toggle(infoWindow, true);
})
这是Logcat给我的错误:
kotlin.TypeCastException: null cannot be cast to non-null type com.example.sampo.luontoalueet.MapInfoWindowFragment
at com.example.sampo.luontoalueet.MainMapsActivity$onMapReady$1.onMapClick(MainMapsActivity.kt:123)
我的问题是如何将该语句更改为非null类型?
val mapInfoWindowFragment = supportFragmentManager.findFragmentById(R.id.infoWindowMap) as MapInfoWindowFragment
答案 0 :(得分:3)
您的findfragmentById
返回null
(表明您的片段不存在)。
如果您现在完全确定片段不能为null
,则需要检查代码。也许您的片段未附加到supportFragmentManager
?
如果要处理此片段可能不存在的情况,则可以使用可为空的强制转换as?
:
val mapInfoWindowFragment = supportFragmentManager.findFragmentById(R.id.infoWindowMap) as? MapInfoWindowFragment
然后,您可以有条件地检查if(mapInfoWindowFragment == null)
并处理空值情况。