为什么在这种情况下 location 总是空的？

Question

谁能告诉我为什么当我在第一个 if 条件下调用函数 initPetrolStationList() 时 currentLocation 总是空的，但是当我调用函数时 addPetrolStation(v: View) 被初始化了？我希望当函数 initPetrolStationList() 被调用时 currentLocation 将不为空。

class PetrolStationListActivity : AppCompatActivity() {

    private lateinit var fusedLocationProviderClient: FusedLocationProviderClient
    private lateinit var listView: RecyclerView
    private var currentLocation: Location? = null

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
//some code
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.petrol_station_list_view)
        requestLocationPermission()
        fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this)
        getLastLocation()
        initPetrolStationList()
    }


    fun addPetrolStation(v: View) {
        if (currentLocation != null) {
            val googleMapController = GoogleMapsController()
            googleMapController.getPetrolStationFromGoogle(object : GoogleResponse {
                override fun getLocation(): Location = currentLocation!!
                override fun getResponse(body: GoogleMapResponse) {
                    if (body.status == "OK") {
                        val intent = Intent(applicationContext, PetrolStationActivity::class.java)
                        v.context.startActivity(intent)
                    } else {
                        Toast.makeText(applicationContext, "Petrol station not found", Toast.LENGTH_LONG).show()
                    }
                }
            })
        }
    }

    @SuppressLint("MissingPermission")
    private fun getLastLocation() {
        fusedLocationProviderClient.lastLocation.addOnCompleteListener {
            if (it.isSuccessful) {
                currentLocation = it.result!!
                Log.d("Current location: ", "Lat:${currentLocation!!.latitude}, Lng:${currentLocation!!.longitude}")
            } else {
                Log.d("Location exception: ", it.exception?.message)
                Toast.makeText(this, "Location not found :( ", Toast.LENGTH_LONG).show()
            }
        }
    }

    private fun initPetrolStationList() {
        if (currentLocation != null) {
            val petrolStationController = PetrolStationController()
           //some code
        } else Toast.makeText(this, "Location not found", Toast.LENGTH_LONG).show()
    }

}

Answer 1

如果您在 currentLocation = it.result!! 之后从 getLastLocation 内部调用 initPetrolStationList，那么 currentLocation 将不会为空。

Answer 2

尝试立即初始化 petrolStationController
在onCreate

fusedLocationProviderClient.lastLocation.addOnCompleteListener

并在此监听器中更新 petrolStationController 的数据

为什么在这种情况下 location 总是空的？

Why location is allways null in this case?

android

location

kotlin