Show current latitude & longitude in Kotlin

MainActivity.kt

package com.anta40.app.locationtest

import android.Manifest
import android.content.Context
import android.content.DialogInterface
import android.content.Intent
import android.content.pm.PackageManager
import android.location.Location
import android.location.LocationManager
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.provider.Settings
import android.support.v4.app.ActivityCompat
import android.support.v4.content.ContextCompat
import android.support.v7.app.AlertDialog
import android.widget.Toast
import com.google.android.gms.common.ConnectionResult
import com.google.android.gms.common.api.GoogleApiClient
import com.google.android.gms.location.FusedLocationProviderClient
import com.google.android.gms.location.LocationRequest
import com.google.android.gms.location.LocationServices
import com.google.android.gms.tasks.OnSuccessListener
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity(), GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener,
    com.google.android.gms.location.LocationListener {

    private val TAG = "MainActivity"
    private lateinit var mGoogleApiClient: GoogleApiClient
    private var mLocationManager: LocationManager? = null
    lateinit var mLocation: Location
    private var mLocationRequest: LocationRequest? = null
    private val listener: com.google.android.gms.location.LocationListener? = null
    private val UPDATE_INTERVAL = (2 * 1000).toLong()  /* 10 secs */
    private val FASTEST_INTERVAL: Long = 2000 /* 2 sec */
    private val MY_PERMISSIONS_REQUEST_ACCESS_LOCATION = 123
    lateinit var locationManager: LocationManager

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        mGoogleApiClient = GoogleApiClient.Builder(this)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .addApi(LocationServices.API)
            .build()

        mLocationManager = this.getSystemService(Context.LOCATION_SERVICE) as LocationManager

        checkLocation()
    }

    override fun onStart() {
        super.onStart()
        if (mGoogleApiClient != null) {
            mGoogleApiClient.connect();
        }
    }

    override fun onStop() {
        super.onStop()
        if (mGoogleApiClient.isConnected()) {
            mGoogleApiClient.disconnect();
        }
    }

    override fun onConnected(p0: Bundle?) {

        if (ContextCompat.checkSelfPermission(this@MainActivity,
                Manifest.permission.ACCESS_FINE_LOCATION)
            != PackageManager.PERMISSION_GRANTED) {

            // Permission is not granted
            // Should we show an explanation?
            if (ActivityCompat.shouldShowRequestPermissionRationale(this@MainActivity,
                    Manifest.permission.ACCESS_FINE_LOCATION)) {
                // Show an explanation to the user *asynchronously* -- don't block
                // this thread waiting for the user's response! After the user
                // sees the explanation, try again to request the permission.
            } else {
                // No explanation needed, we can request the permission.
             //   ActivityCompat.requestPermissions(this@MainActivity,
              //      arrayOf(Manifest.permission.READ_CONTACTS),
               //     MY_PERMISSIONS_REQUEST_ACCESS_LOCATION)
                    showPermissionRequest()

            }
        } else {
            // Permission has already been granted
            var fusedLocationProviderClient :
                    FusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
            fusedLocationProviderClient .getLastLocation()
                .addOnSuccessListener(this, OnSuccessListener<Location> { location ->
                    // Got last known location. In some rare situations this can be null.
                    if (location != null) {
                        // Logic to handle location object
                        mLocation = location;
                        txt_latitude.setText("" + mLocation.latitude)
                        txt_longitude.setText("" + mLocation.longitude)
                        Toast.makeText(
                            applicationContext, "Position: (" + mLocation.latitude.toString() + "," +
                                    mLocation.longitude.toString()+")",
                            Toast.LENGTH_SHORT
                        ).show()
                    }
                })
        }

       startLocationUpdates();

    }

    override fun onConnectionSuspended(p0: Int) {
        mGoogleApiClient.connect();
        Toast.makeText(applicationContext, "Connection suspended...", Toast.LENGTH_SHORT).show()
    }

    override fun onConnectionFailed(p0: ConnectionResult) {
        Toast.makeText(applicationContext, "Connection error: "+p0.errorMessage, Toast.LENGTH_SHORT).show()
    }

    override fun onLocationChanged(p0: Location?) {
        if (p0 != null) {
            Toast.makeText(
                applicationContext, "Position: (" + p0.latitude.toString() + "," + p0.longitude.toString()+")",
                Toast.LENGTH_SHORT
            ).show()

            txt_latitude.setText("" + mLocation.latitude)
            txt_longitude.setText("" + mLocation.longitude)
        }
    }

    private fun checkLocation(): Boolean {
        if(!isLocationEnabled())
            showAlert();
        return isLocationEnabled();
    }

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

    private fun showPermissionRequest(){
        val dialog = AlertDialog.Builder(this)
        dialog.setTitle("Enable Location")
            .setMessage("Your Locations Settings is set to 'Off'.\nPlease Enable Location to " + "use this app")
            .setPositiveButton("Location Settings", DialogInterface.OnClickListener { paramDialogInterface, paramInt ->
                ActivityCompat.requestPermissions(this@MainActivity,
                    arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
                    MY_PERMISSIONS_REQUEST_ACCESS_LOCATION);
            })
            .setNegativeButton("Cancel", DialogInterface.OnClickListener { paramDialogInterface, paramInt -> })
        dialog.show()
    }

    private fun showAlert() {
        val dialog = AlertDialog.Builder(this)
        dialog.setTitle("Enable Location")
            .setMessage("Your Locations Settings is set to 'Off'.\nPlease Enable Location to " + "use this app")
            .setPositiveButton("Location Settings", DialogInterface.OnClickListener { paramDialogInterface, paramInt ->
                val myIntent = Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS)
                startActivity(myIntent)
            })
            .setNegativeButton("Cancel", DialogInterface.OnClickListener { paramDialogInterface, paramInt -> })
        dialog.show()
    }

    protected fun startLocationUpdates() {

        // Create the location request
        mLocationRequest = LocationRequest.create()
            .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
            .setInterval(UPDATE_INTERVAL)
            .setFastestInterval(FASTEST_INTERVAL);
        // Request location updates
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            return;
        }
        LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,
            mLocationRequest, this);
    }

}