Android Studio无法获取定位，调用getLatitude空指针异常如何解决

错误原因 #

你遇到的空指针异常是调用fusedLocationClient.lastLocation时触发，该接口仅返回系统缓存的历史位置，无有效缓存时就会返回null，直接调用getLatitude()方法就会触发空引用异常，且该接口本身就不满足实时定位的需求。

修复步骤 #

你需要改用requestLocationUpdates主动发起实时定位请求，具体修改如下：

1. 新增位置相关API导入
2. 初始化定位请求配置与定位结果回调
3. 替换原有缓存定位逻辑为主动实时定位
4. 补全权限回调逻辑，新增生命周期资源释放避免内存泄漏

完整修改后代码 #

import android.Manifest
import android.content.Context
import android.content.pm.PackageManager
import android.location.LocationManager
import android.os.Bundle
import android.os.Looper
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.google.android.gms.location.FusedLocationProviderClient
import com.google.android.gms.location.LocationCallback
import com.google.android.gms.location.LocationRequest
import com.google.android.gms.location.LocationResult
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.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
    // 新增：定位请求配置
    private lateinit var locationRequest: LocationRequest
    // 新增：定位结果回调
    private lateinit var locationCallback: LocationCallback


    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        binding = FragmentMapBinding.inflate(layoutInflater)

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

        fusedLocationClient = LocationServices.getFusedLocationProviderClient(requireActivity())
        // 初始化定位配置
        initLocationConfig()

        return binding.root
    }

    // 新增：初始化定位请求和回调逻辑
    private fun initLocationConfig() {
        locationRequest = LocationRequest.create().apply {
            // 定位间隔，单位毫秒，可按需调整
            interval = 5000
            // 最快定位间隔
            fastestInterval = 2000
            // 高精度定位模式，优先使用GPS
            priority = LocationRequest.PRIORITY_HIGH_ACCURACY
        }
        // 定位结果回调
        locationCallback = object : LocationCallback() {
            override fun onLocationResult(locationResult: LocationResult) {
                super.onLocationResult(locationResult)
                val location = locationResult.lastLocation ?: return
                // 拿到实时定位后执行逻辑
                moveCamera(LatLng(location.latitude, location.longitude))
                mMap.isMyLocationEnabled = true
                // 如果只需要一次定位，拿到结果后就停止定位，降低功耗
                stopLocationUpdate()
            }
        }
    }

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

    private fun isLocationEnabled(): Boolean {
        val locationManager = activity?.getSystemService(Context.LOCATION_SERVICE) as LocationManager?
        // 避免空指针强转崩溃
        return locationManager?.let {
            it.isProviderEnabled(LocationManager.GPS_PROVIDER) || it.isProviderEnabled(LocationManager.NETWORK_PROVIDER)
        } ?: false
    }

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

    // 修改：替换原有缓存定位逻辑为实时定位请求
    private fun getLocation() {
        if (isLocationEnabled()) {
            if (ActivityCompat.checkSelfPermission(
                    requireContext(),
                    Manifest.permission.ACCESS_FINE_LOCATION
                ) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
                    requireContext(),
                    Manifest.permission.ACCESS_COARSE_LOCATION
                ) != PackageManager.PERMISSION_GRANTED
            ) {
                return
            }
            fusedLocationClient.requestLocationUpdates(
                locationRequest,
                locationCallback,
                Looper.getMainLooper()
            )
        } else {
            createAlertEnableLocation(requireContext())
        }
    }

    // 新增：停止定位请求
    private fun stopLocationUpdate() {
        fusedLocationClient.removeLocationUpdates(locationCallback)
    }

    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
            )
        }
    }

    // 修复：权限授权后主动调用定位
    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<String>,
        grantResults: IntArray
    ) {
        mLocationPermissionsGranted = false
        when (requestCode) {
            LOCATION_PERMISSION_REQUEST_CODE -> {
                if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    mLocationPermissionsGranted = true
                    getLocation()
                }
            }
        }
    }

    // 新增：页面不可见时停止定位，避免内存泄漏和不必要的功耗
    override fun onStop() {
        super.onStop()
        stopLocationUpdate()
    }
}

注意事项 #

• 确保你module级的build.gradle文件中已经引入了定位依赖：

  implementation "com.google.android.gms:play-services-location:21.0.1"
  

  版本号可以替换为官方最新稳定版
• 如果你的App适配Android 12及以上系统（targetSdk >= 31），需要在AndroidManifest.xml中补充对应定位权限声明，后台定位还需要额外申请ACCESS_BACKGROUND_LOCATION权限
• 可根据业务需求调整定位间隔，不需要高频定位时尽量调大间隔减少功耗

内容的提问来源于stack exchange，提问作者user15608723