无法在 android 工作室获取位置

Question

它给了我这个错误（空对象引用上的双 android.location.Location.getLatitude()'）

我尝试了很多不同的解决方案，但都是一样的，我知道 fusedLocationClient.lastLocation 它只是给出了来自其他应用程序的最后位置，但我不想那样，我想获取当前位置没有它，因为它给空？那么如何解决这个问题并获取当前位置？？？

import android.Manifest
import android.content.ContentValues.TAG
import android.content.Context
import android.content.pm.PackageManager
import android.location.LocationManager
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import androidx.fragment.app.Fragment
import com.firebase.geofire.GeoFire
import com.firebase.geofire.GeoLocation
import com.firebase.geofire.GeoQueryEventListener
import com.google.android.gms.location.FusedLocationProviderClient
import com.google.android.gms.location.LocationServices
import com.google.android.gms.maps.CameraUpdateFactory
import com.google.android.gms.maps.GoogleMap
import com.google.android.gms.maps.OnMapReadyCallback
import com.google.android.gms.maps.SupportMapFragment
import com.google.android.gms.maps.model.LatLng
import com.google.android.gms.maps.model.MarkerOptions
import com.google.firebase.database.DatabaseError
import com.google.firebase.database.FirebaseDatabase
import com.moapp.guardaroundd.R
import com.moapp.guardaroundd.databinding.FragmentMapBinding
import com.moapp.guardaroundd.utils.Constants.DEFAULT_ZOOM
import com.moapp.guardaroundd.utils.Constants.LOCATION_PERMISSION_REQUEST_CODE
import com.moapp.guardaroundd.utils.createAlertEnableLocation


class MapFragment : Fragment(), OnMapReadyCallback {

   private lateinit var mMap: GoogleMap
   private lateinit var binding: FragmentMapBinding
   private lateinit var fusedLocationClient: FusedLocationProviderClient
   private var mLocationPermissionsGranted = false


   override fun onCreateView(
       inflater: LayoutInflater, container: ViewGroup?,
       savedInstanceState: Bundle?
   ): View {
       // Inflate the layout for this fragment
       binding = FragmentMapBinding.inflate(layoutInflater)

       val mapFragment = childFragmentManager.findFragmentById(R.id.map) as SupportMapFragment
       mapFragment.getMapAsync(this)

       fusedLocationClient = LocationServices.getFusedLocationProviderClient(requireActivity())


       return binding.root
   }

   override fun onMapReady(googleMap: GoogleMap) {
       mMap = googleMap

       getLocationPermission()

   }

   private fun isLocationEnabled(): Boolean {
       val locationManager =
           activity?.getSystemService(Context.LOCATION_SERVICE) as LocationManager?
       return locationManager!!.isProviderEnabled(LocationManager.GPS_PROVIDER) || locationManager.isProviderEnabled(
           LocationManager.NETWORK_PROVIDER
       )
   }

   private fun moveCamera(latLng: LatLng) {
       mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, DEFAULT_ZOOM))
   }

      private fun getLocation() {

       if (isLocationEnabled()) {
           try {
               fusedLocationClient.lastLocation.addOnSuccessListener {
                   moveCamera(LatLng(it.latitude, it.longitude))
                   mMap.isMyLocationEnabled = true
               }
           } catch (ex: SecurityException) {

           }
       } else {
           //Custom alert
           createAlertEnableLocation(requireContext())
       }

   }

   private fun getLocationPermission() {
       if (ContextCompat.checkSelfPermission(
               requireContext(),
               Manifest.permission.ACCESS_FINE_LOCATION
           )
           == PackageManager.PERMISSION_GRANTED
       ) {
           mLocationPermissionsGranted = true
           getLocation()

       } else {
           ActivityCompat.requestPermissions(
               requireActivity(), arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
               LOCATION_PERMISSION_REQUEST_CODE
           )
       }
   }


   override fun onRequestPermissionsResult(
       requestCode: Int,
       permissions: Array<String>,
       grantResults: IntArray
   ) {
       mLocationPermissionsGranted = false
       when (requestCode) {
           LOCATION_PERMISSION_REQUEST_CODE -> {

               // If request is cancelled, the result arrays are empty.
               if (grantResults.isNotEmpty() &&
                   grantResults[0] == PackageManager.PERMISSION_GRANTED
               ) {
                   mLocationPermissionsGranted = true
               }
           }
       }
   }

Answer 1

避免 null location 的最简单方法是启动 Google 地图应用程序 并按我的位置按钮。然后您返回您的应用，fusedLocationClient.lastLocation 这次将为您提供非空设备的最后位置。

既然您显然不喜欢这个，那么您需要使用 Location Updates。

为此，我会稍微调整一下您的 getLocation() 代码。

private fun getLocation() {
        // last known location from fusedLocationProviderClient returned as a task
        fusedLocationProviderClient.lastLocation
                //check if the last location is null
            .addOnSuccessListener { lastLoc ->
                if (lastLoc != null) {

                    // initialize lastKnownLocation from fusedLocationProviderClient
                    lastKnownLocation = lastLoc
                    moveCamera(LatLng(lastLoc.latitude, lastLoc.longitude))
                } else {
                    //if null trigger location update to get location
                    fusedLocationProviderClient.requestLocationUpdates(
                        locationRequest, locationCallback, Looper.getMainLooper()
                    )
                }
                // in case of error Toast the error in a short Toast message
            }
            .addOnFailureListener {

                Toast.makeText(requireActivity(), "${it.message}", Toast.LENGTH_SHORT).show()
            }
    }

我还需要将 LocationRequest 和 Location Callback 引入游戏中。

class MapFragment : Fragment(), OnMapReadyCallback { .......

    // LOCATION COMPONENTS
    private lateinit var lastKnownLocation: Location
    private lateinit var fusedLocationProviderClient: FusedLocationProviderClient

    private val locationRequest =
        LocationRequest().apply {
            priority = LocationRequest.PRIORITY_HIGH_ACCURACY
            interval = TimeUnit.SECONDS.toMillis(10)
            fastestInterval = TimeUnit.SECONDS.toMillis(1)
        }


    private val locationCallback =
        object : LocationCallback() {

            override fun onLocationResult(locationResult: LocationResult?) {
                super.onLocationResult(locationResult)

                if (locationResult != null) {

                    lastKnownLocation = locationResult.lastLocation
                      //call the above getLocation() again to move camera
                   getLocation()
                }
            }
        }

因此，只要来自 fusedClient 的最后一个已知位置为空，就会触发更新并移动相机位置。

无法在 android 工作室获取位置

can't get location in android studio

android

google-maps

google-maps-android-api-2

android-studio