get amount of lat and lon

Question

i got location and i have latitude and longitude in the method of getLocation and declared local variable lat and lon in the class and default 0.0 when i pass that in to the api focast showed lat and lon 0.0 just show lat and lon in the method out of method return 0.0

class MainActivity : AppCompatActivity() {

    val PERMISSION_ID = 42
    val CITY: String = "kalaleh"
    val API: String = "837f502858a52a78b98b5d7be51d0741"
    lateinit var mFusedLocationClient: FusedLocationProviderClient
       var lat :Double = 0.0
       var lon:Double= 0.0



    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this)

        getLastLocation()


    }

    override fun onStart() {
        super.onStart()
        weatherTask().execute()

    }



    private fun checkPermissions(): Boolean {
        if (ActivityCompat.checkSelfPermission(
                this,
                Manifest.permission.ACCESS_COARSE_LOCATION
            ) == PackageManager.PERMISSION_GRANTED &&
            ActivityCompat.checkSelfPermission(
                this,
                Manifest.permission.ACCESS_FINE_LOCATION
            ) == PackageManager.PERMISSION_GRANTED
        ) {
            return true
        }
        return false
    }

    private fun requestPermissions() {
        ActivityCompat.requestPermissions(
            this,
            arrayOf(
                Manifest.permission.ACCESS_COARSE_LOCATION,
                Manifest.permission.ACCESS_FINE_LOCATION
            ),
            PERMISSION_ID
        )
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<String>,
        grantResults: IntArray
    ) {
        if (requestCode == PERMISSION_ID) {
            if ((grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED)) {
                // Granted. Start getting the location information
            }
        }
    }

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

    @SuppressLint("MissingPermission")
    private fun getLastLocation() {
        if (checkPermissions()) {
            if (isLocationEnabled()) {

                mFusedLocationClient.lastLocation.addOnCompleteListener(this) { task ->
                    var location: Location? = task.result
                    if (location == null) {
                        requestNewLocationData()
                    } else {
                      lat=location.latitude
                      lon=location.longitude

                        Log.i("getLOc","lat is : $lat")
                        Log.i("getLOc","lat is : $lon")

                    }
                }
            } else {
                Toast.makeText(this, "Turn on location", Toast.LENGTH_LONG).show()
                val intent = Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS)
                startActivity(intent)
            }
        } else {
            requestPermissions()
        }

    }

    @SuppressLint("MissingPermission")
    private fun requestNewLocationData() {
        var mLocationRequest = LocationRequest()
        mLocationRequest.priority = LocationRequest.PRIORITY_HIGH_ACCURACY
        mLocationRequest.interval = 1000
        mLocationRequest.fastestInterval = 5000
        mLocationRequest.numUpdates = 1

        mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
        mFusedLocationClient!!.requestLocationUpdates(
            mLocationRequest, mLocationCallback,
            Looper.myLooper()
        )
    }

    private val mLocationCallback = object : LocationCallback() {
        override fun onLocationResult(locationResult: LocationResult) {
            var mLastLocation: Location = locationResult.lastLocation
            findViewById<TextView>(R.id.latTextView).text = mLastLocation.latitude.toString()
            findViewById<TextView>(R.id.lonTextView).text = mLastLocation.longitude.toString()
            lat=mLastLocation.latitude
            lon=mLastLocation.longitude




        }
    }

    inner class weatherTask() : AsyncTask<String, Void, String>() {
        override fun onPreExecute() {
            super.onPreExecute()
            /* Showing the ProgressBar, Making the main design GONE */
            findViewById<ProgressBar>(R.id.loader).visibility = View.VISIBLE
            findViewById<RelativeLayout>(R.id.mainContainer).visibility = View.GONE
            findViewById<TextView>(R.id.errorText).visibility = View.GONE
        }

        override fun doInBackground(vararg params: String?): String? {
            var response: String?
            try {
                Log.i("doINb","lat is : $lat")
                Log.i("doINb","lon is : $lon")


                response = URL("https://api.openweathermap.org/data/2.5/weather?lat=$lat&lon=$lon&units=metric&appid=$API").readText(
                    Charsets.UTF_8
                )
            } catch (e: Exception) {
                response = null
            }
            return response
        }

        override fun onPostExecute(result: String?) {
            super.onPostExecute(result)
            try {
                /* Extracting JSON returns from the API */
                val jsonObj = JSONObject(result)
                val main = jsonObj.getJSONObject("main")
                val sys = jsonObj.getJSONObject("sys")
                val wind = jsonObj.getJSONObject("wind")
                val weather = jsonObj.getJSONArray("weather").getJSONObject(0)

                val updatedAt: Long = jsonObj.getLong("dt")
                val updatedAtText =
                    "Updated at: " + SimpleDateFormat("dd/MM/yyyy hh:mm a", Locale.ENGLISH).format(
                        Date(updatedAt * 1000)
                    )
                val temp = main.getString("temp") + "°C"
                val tempMin = "Min Temp: " + main.getString("temp_min") + "°C"
                val tempMax = "Max Temp: " + main.getString("temp_max") + "°C"
                val pressure = main.getString("pressure")
                val humidity = main.getString("humidity")

                val sunrise: Long = sys.getLong("sunrise")
                val sunset: Long = sys.getLong("sunset")
                val windSpeed = wind.getString("speed")
                val weatherDescription = weather.getString("description")

                val address = jsonObj.getString("name") + ", " + sys.getString("country")

                /* Populating extracted data into our views */
                findViewById<TextView>(R.id.address).text = address
                findViewById<TextView>(R.id.updated_at).text = updatedAtText
                findViewById<TextView>(R.id.status).text = weatherDescription.capitalize()
                findViewById<TextView>(R.id.temp).text = temp
                findViewById<TextView>(R.id.temp_min).text = tempMin
                findViewById<TextView>(R.id.temp_max).text = tempMax
                findViewById<TextView>(R.id.sunrise).text =
                    SimpleDateFormat("hh:mm a", Locale.ENGLISH).format(Date(sunrise * 1000))
                findViewById<TextView>(R.id.sunset).text =
                    SimpleDateFormat("hh:mm a", Locale.ENGLISH).format(Date(sunset * 1000))
                findViewById<TextView>(R.id.wind).text = windSpeed
                findViewById<TextView>(R.id.pressure).text = pressure
                findViewById<TextView>(R.id.humidity).text = humidity

                /* Views populated, Hiding the loader, Showing the main design */
                findViewById<ProgressBar>(R.id.loader).visibility = View.GONE
                findViewById<RelativeLayout>(R.id.mainContainer).visibility = View.VISIBLE

            } catch (e: Exception) {
                findViewById<ProgressBar>(R.id.loader).visibility = View.GONE
                findViewById<TextView>(R.id.errorText).visibility = View.VISIBLE

            }

        }
    }
}

Answer 1

In getLastLocation(), you added an onCompleteListener to the last location. You try to get an initial value of lat lon through last location, then get continuous return as location updates.

You might assume task.result to be null at first, then requestNewLocationData() would be called. Instead you see the log output. That means it gives you a one-time output of 0.0, 0.0, which is the default value if there is no last known location.

You should call requestNewLocationData() no matter task.result is null or not.