Improved version!
The following code shows how to ACCESS_FINE_LOCATION. While longer than my original code it is preferred because it stops GPS updates when the App is Paused or Stopped.
Due to issues with the Android Studio emulators it also includes a simple watchdog timer reporting the GPS Updates have stopped if no updates are received for approximately 10 seconds
const val PERMISSIONS_REQUEST_ACCESS_LOCATION = 99 // any positive value
class MainActivity : AppCompatActivity() {
private lateinit var tvCurrentTime : TextView
private lateinit var tvSpeed : TextView
private lateinit var tvBearing : TextView
private var myTimer: Timer = Timer()
private var sHourMinuteSecond : String = "00:00:00"
private lateinit var fusedLocationClient : FusedLocationProviderClient
private lateinit var locationCallback: LocationCallback
private var gpsWatchDog : Int = 0
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
tvCurrentTime = findViewById<View>(R.id.show_time_textview) as TextView
tvSpeed = findViewById<View>(R.id.speed_textview) as TextView
tvBearing = findViewById<View>(R.id.bearing_textview) as TextView
fusedLocationClient = LocationServices.getFusedLocationProviderClient(this@MainActivity) as FusedLocationProviderClient
locationCallback = object : LocationCallback() {
override fun onLocationResult(locationResult: LocationResult) {
super.onLocationResult(locationResult)
processNewLocation(locationResult.lastLocation) // only process the lastLocation (may be others)
}
}
}
private fun checkPermissionsForGPSUpdates() {
if ((ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) ||
(ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED)) {
// Android wants us to request both COARSE and FINE permissions
writeToLog("checkSelfPermission Permission Not Granted so requesting!")
ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION), PERMISSIONS_REQUEST_ACCESS_LOCATION)
// During requestPermission OnPause() is called
// When user grants permission OnResume() is called which once again calls checkPermissionsForGPSUpdates() when GPS updates should commence
return
}
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
// only run if we have FINE location
writeToLog("ACCESS_FINE_LOCATION Permission Granted start GPS updates !")
val locationRequest: LocationRequest = LocationRequest.create().apply {
interval = 1000
fastestInterval = 500
priority = LocationRequest.PRIORITY_HIGH_ACCURACY
}
try {
if (!fusedLocationClient.requestLocationUpdates(locationRequest, locationCallback, Looper.getMainLooper()).isSuccessful) {
writeToLog("requestLocationUpdates() was unsuccessful") // Stackoverflow indicates this may actually be a google error
}
} catch (unlikely: SecurityException) {
writeToLog("Lost location permission. Could not request updates. $unlikely")
}
} else {
writeToLog("Permissions Not Granted so exit")
Toast.makeText(this@MainActivity, "App will not run without GPS" , Toast.LENGTH_LONG).show()
finish()
}
}
private fun updateTimeString() {
// Called by the timer DO NOT put code affecting the UI in here!!!
val systemTime = GregorianCalendar()
sHourMinuteSecond = SimpleDateFormat("HH:mm:ss").format(systemTime.timeInMillis)
// Use the runOnUiThread method to update the display
this.runOnUiThread(updateDisplay)
}
private val updateDisplay = Runnable {
// This method runs in the same thread as the User Interface
// due to continuous crashing of the emulator has been written to be short
tvCurrentTime.text = sHourMinuteSecond
if (++gpsWatchDog > 10) {
tvBearing.text = "No GPS"
}
}
private fun processNewLocation(latestLocation : Location) {
// reset the watchdog since we have received a GPS update
gpsWatchDog = 0
// do something with the latest location
// for now just show the GPS time
val sSpeed = SimpleDateFormat("HH:mm:ss").format(latestLocation.time)
tvSpeed.text = sSpeed
val sBearing = latestLocation.bearing.roundToInt().toString() // no decimal places
tvBearing.text = sBearing
}
override fun onResume() {
super.onResume()
writeToLog("Called onResume()")
// start the GPS updates (after checking user permission)
checkPermissionsForGPSUpdates()
val currentSystemTime = System.currentTimeMillis()
// start a timer to update the time
myTimer = Timer()
val delayToNextWholeSecond = ((currentSystemTime / 1000) + 1) * 1000 - currentSystemTime // Synchronise to whole seconds
myTimer.scheduleAtFixedRate(object : TimerTask() {
override fun run() {
updateTimeString()
}
}, delayToNextWholeSecond, 1000)
}
override fun onPause() {
super.onPause()
writeToLog("onPause()")
myTimer.cancel() // stop the existing timer
myTimer.purge()
fusedLocationClient.removeLocationUpdates(locationCallback)
}
override fun onStop() {
super.onStop()
writeToLog("onStop()")
myTimer.cancel()
myTimer.purge()
fusedLocationClient.removeLocationUpdates(locationCallback)
}
private fun writeToLog(message : String) {
Log.d("SmallGPSDemo", message)
}
}
The original very short example is shown below only to show Android's new RequestPermission() to obtain permissions (and start updates)
class MainActivity : AppCompatActivity() {
private var debugTextView : TextView? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
debugTextView = findViewById<View>(R.id.debug_textview) as TextView
// this checks permission and starts the location updates
requestPermission.launch(Manifest.permission.ACCESS_FINE_LOCATION)
}
private fun processNewLocation(latestLocation : Location) {
// do something with the location
debugTextView!!.text = SimpleDateFormat("hh:mm:ss.SSS").format(System.currentTimeMillis())
}
@SuppressLint("MissingPermission")
private val requestPermission =
registerForActivityResult(ActivityResultContracts.RequestPermission()) { isGranted ->
if (isGranted) {
// Permissions granted so start GPS updates
val locationRequest: LocationRequest = LocationRequest.create().apply {
interval = 1000
fastestInterval = 500
priority = LocationRequest.PRIORITY_HIGH_ACCURACY
}
val locationCallback = object : LocationCallback() {
override fun onLocationResult(locationResult: LocationResult) {
super.onLocationResult(locationResult)
for (location in locationResult.locations) {
processNewLocation(location) // Settings should only give one location but ...
}
}
}
val fusedLocationClient = LocationServices.getFusedLocationProviderClient(this@MainActivity)
fusedLocationClient.requestLocationUpdates(locationRequest, locationCallback, Looper.getMainLooper())
} else {
Log.d("DEBUG", "permission denied ")
Toast.makeText(this@MainActivity, "This activity will not run unless you allow GPS", Toast.LENGTH_LONG).show()
finish()
}
}
}
Reminder add location permissions to the AndroidManifest file
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.reallysmallgpscode">
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.ReallySmallGPSCode">
<activity
android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Hopefully others find the code useful
