如何从Android中的地图获取当前位置

Question

在我的应用程序中，我想使用mapBox在我的应用程序中使用地图，并且我希望在加载应用程序时显示当前位置。我写下面的代码，但是当运行应用程序时，在logcat（不强制关闭）和not load map中显示错误！我的活动代码：

class AddressMapPage : BaseActivity(), LocationEngineListener {

    override var layoutId: Int = R.layout.activity_address_map_page
    override var context: Context = this
    private lateinit var mapirMap: MapirMap
    private lateinit var latLng: LatLng

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        //Hide status bar
        window.setFlags(
            WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN
        )

        (supportFragmentManager.findFragmentById(R.id.myMapView) as SupportMapFragment)
            .getMapAsync { mapirMap ->

                [email protected] = mapirMap

                imageView2.setOnClickListener {
                    latLng = mapirMap.cameraPosition.target
                    toast(latLng.toString())
                    Log.e("TalAndLog", latLng.toString())
                }

                getLocationPermission()
            }
    }

    private fun getLocationPermission() {
        KotlinPermissions.with(this)
            .permissions(Manifest.permission.ACCESS_FINE_LOCATION)
            .onAccepted {
                currentLocation()
            }
            .onDenied {
                toast("Not allowed error message")
            }
            .onForeverDenied {
                toast("Not allowed error message")
            }
            .ask()
    }

    private fun currentLocation() {
        val component = mapirMap.locationComponent
        component.activateLocationComponent(context)
        component.isLocationComponentEnabled = true
        if (component.locationEngine != null) {
            component.locationEngine!!.addLocationEngineListener(this)
        }
        mapirMap.animateCamera(
            CameraUpdateFactory
                .newLatLngZoom(
                    LatLng(
                        component.lastKnownLocation!!.latitude,
                        component.lastKnownLocation!!.longitude
                    ), 14.0
                )
        )
    }

    override fun onLocationChanged(location: Location?) {
        if (location != null)
            mapirMap.animateCamera(
                CameraUpdateFactory.newLatLngZoom(
                    LatLng(
                        location.latitude,
                        location.longitude
                    ), 14.0
                )
            )
    }

    override fun onConnected() {
    }
}

Logcat错误：

kotlin.KotlinNullPointerException
        at com.app.ui.address.map.AddressMapPage.currentLocation(AddressMapPage.kt:77)
        at com.app.ui.address.map.AddressMapPage.access$currentLocation(AddressMapPage.kt:20)
        at com.app.ui.address.map.AddressMapPage$getLocationPermission$1.invoke(AddressMapPage.kt:55)
        at com.app.ui.address.map.AddressMapPage$getLocationPermission$1.invoke(AddressMapPage.kt:20)
        at com.kotlinpermissions.KotlinPermissions$PermissionCore$onAccepted$1.onResult(KotlinPermissions.kt:56)
        at com.kotlinpermissions.KotlinPermissions$PermissionCore.onReceivedPermissionResult$kotlin_permissions_release(KotlinPermissions.kt:36)
        at com.kotlinpermissions.KotlinPermissions$PermissionCore.onAcceptedPermission(KotlinPermissions.kt:132)
        at com.kotlinpermissions.KotlinPermissions$PermissionCore.ask(KotlinPermissions.kt:107)
        at com.app.ui.address.map.AddressMapPage.getLocationPermission(AddressMapPage.kt:63)
        at com.app.ui.address.map.AddressMapPage.access$getLocationPermission(AddressMapPage.kt:20)
        at com.app.ui.address.map.AddressMapPage$onCreate$1.onMapReady(AddressMapPage.kt:47)
        at ir.map.sdk_map.maps.SupportMapFragment.onMapReady(SupportMapFragment.java:124)
        at ir.map.sdk_map.maps.MapView$MapCallback.onMapReady(MapView.java:1663)
        at ir.map.sdk_map.maps.MapView$MapCallback.onDidFinishLoadingStyle(MapView.java:1701)
        at ir.map.sdk_map.maps.MapChangeReceiver.onDidFinishLoadingStyle(MapChangeReceiver.java:195)
        at ir.map.sdk_map.maps.NativeMapView.onDidFinishLoadingStyle(NativeMapView.java:995)
        at android.os.MessageQueue.nativePollOnce(Native Method)

为此错误向我显示line：component.lastKnownLocation!!.latitude,

我该如何解决？

Answer 1

Mapbox文档中的[This example显示了用于在地图上显示用户位置的推荐方法。

由于您正在使用Kotlin的not-null assertion operator（!!），因此由于kotlin.KotlinNullPointerException为空的事实而抛出了component.lastKnownLocation。在链接的示例中不会发生此问题，因为在enableLocationComponent回调中调用了onMapReady方法。 enableLocationComponent方法执行必要的设置，以将LocationComponent实例与Mapbox映射一起使用。