Strange error into code to get current location with android - java

I created my own Java Class to handle the location:
public class MyLocationHandler extends Service implements LocationListener {
......
public Location getLocation() {
try {
locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE);
// getting GPS status
isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPSEnabled && !isNetworkEnabled) {
// no network provider is enabled
} else {
this.canGetLocation = true;
// First get location from Network Provider
if (isNetworkEnabled) {
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
.......
}
And this is an extract from build.gradle:
android {
compileSdkVersion 23
buildToolsVersion "24.0.0"
defaultConfig {
applicationId "com.mobile.appoperator"
minSdkVersion 15
targetSdkVersion 23
versionCode 1
versionName "1.0"
}
PROBLEM:
The problem is that I need to add checkSelfPermission, but that isn't an activity and plus if I add it, I can't run my app on Android versions older than api lvl 23.
So how can I handle this problem?

I am doing mine inside a service and yes, I currently do not request permission because for some reason, you have to be inside an activity to do that;
Here is what I do instead:
private void updateUserLocation(){
if ( Build.VERSION.SDK_INT >= 23 &&
ContextCompat.checkSelfPermission( getApplicationContext(), android.Manifest.permission.ACCESS_FINE_LOCATION )
!= PackageManager.PERMISSION_GRANTED &&
ContextCompat.checkSelfPermission( getApplicationContext(), android.Manifest.permission.ACCESS_COARSE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
return;
}
locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
if (locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)){
LocationListener listener = new GpsListener();
Looper.prepare();
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, listener);
Looper.loop();
}else {
if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
LocationListener listener = new GpsListener();
Looper.prepare();
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, listener);
Looper.loop();
}
}
}
The best approach to actually request a user to grant you permission is to do this early perhaps in the first activity of the app like Login (then they will see some window explaining why you need GPS enabled or such permission in your app.
If the user rejects the request for permission, then you will have to reroute your app - basically feel sad and do what you would do without location features.
SUMMARY
In general, since you only ask the user to grant the permission perhaps once, you can do that when they login (since after they grant the permission, they will then not be asked again), then when actually getting location updates, you can simply check like I do below and move on!
I hope this helps you get somewhere.

Related

Unable to Get Coordinates from Location Service on Android Studio

I am new to Android Studio and am trying to retrieve the co-ordinates of an Android device using Location Service.
I have all the relevant permissions enabled in the manifest (the Coarse and Fine locations, and the Internet).
In my MainActivity.java, I have the following. However, when I run it in Android Studio, for the 3 test cases I have in the activity, the TextView ShowLocation always become "Something else", meaning that it went to the third case where location is null (no location detected?) but permission has been granted properly.
What am I doing wrong here? Is it because I could not test Location Service in Android Studio? How can I test and obtain co-ordinate values in an Android application using Android Studio?
A snippet of MainActivity.java
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_LOCATION);
}
Location loc = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (loc != null) {
latitude = String.valueOf(loc.getLatitude());
showLocation.setText("Latitude" + latitude);
}
else {
if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
showLocation.setText("No GPS Permission granted");
} else
showLocation.setText("Something else");
}

.isProviderEnabled(LocationManager.NETWORK_PROVIDER) returns always false when gps is off?

Is it possible to get the location from NETWORK if GPS is OFF ?
My Demo can get the current user-location from NETWORK and from GPS but only if GPS is ON.
If I try to get the location from LastKnownLocation, I get null too.
#Override
protected void onResume() {
super.onResume();
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
startActivity(new Intent(MainActivity.this, Permissions.class));
return;
}
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
isGPS = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetwork = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPS && !isNetwork) {
Log.d("TAG", "gps and network false");
}else {
if (isGPS) {
loc = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (loc != null) {
Log.i("TAG", "gps loc found");}
}
if (isNetwork) {
loc = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (loc != null) {
Log.i("TAG", "network loc found");
}
}
I have tested this code below. it returns the location null too, if I make the device-gps off :
GPSTracker.java
If you are trying to request the location from the network as a fallback to GPS, you will need to have ACCESS_COARSE_LOCATION enabled. Also, even with the permission enabled, you must request a location update, to refresh and update the last network position. Only after that, you'll have the last known location available, otherwise, you'll get null indeed.
To make your code work, you probably just need to call your GPSTracker.getLocation() before your line with
getSystemService(Context.LOCATION_SERVICE);
You can check the documentation for getLastKnownLocation here:
https://developer.android.com/reference/android/location/LocationManager#getLastKnownLocation(java.lang.String)
Gets the last known location from the given provider, or null if there
is no last known location. The returned location may be quite old in
some circumstances, so the age of the location should always be
checked.
👉   This will never activate sensors to compute a new location, and will
only ever return a cached location.

Getting the user's location in Android when the phone is locked

I am looking for a solution to get the user's location in a specific time-interval in Android API 17 (Android 4.2) and when the phone is locked.
I've already tried some different code, checked a lot tutorials and searched almost everywhere on the web. The solution might be there, but I think it's a combination of lack of experience with Android developing and interpreting the different right solutions and approaches.
At first I had some pretty basic code, which worked very well when the screen was turned on. Even in the background, the location got updated (as I could check via a Toast message with the longitude and latitude).
I used a Handler to do so:
public void locationRunnable() {
final Handler locationHandler = new Handler();
final int distanceDelay = 5000; // milliseconds
locationHandler.postDelayed(new Runnable(){
public void run() {
// code
mMap.clear();
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
mMap.setMyLocationEnabled(true);
mMap.setBuildingsEnabled(true);
mMap.getUiSettings().setMyLocationButtonEnabled(false);
LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
String provider = locationManager.getBestProvider(criteria, true);
myLocation = locationManager.getLastKnownLocation(provider);
if (myLocation != null) {
latitudeCurrentPosition = myLocation.getLatitude();
longitudeCurrentPosition = myLocation.getLongitude();
}
currentPattern = shortTest;
Notification.Builder notificationBuilderChecking = new Notification.Builder(this)
.setSmallIcon(R.mipmap.ic_launcher)
.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))
.setContentTitle("Test app")
.setAutoCancel(true)
.setOnlyAlertOnce(false)
.setContentText("Getting location!")
.setPriority(Notification.PRIORITY_MAX)
.setLights(0xffffffff, 200, 200)
.setVibrate(currentPattern);
Notification notification2 = notificationBuilderChecking.build();
NotificationManager notificationMngr2 = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
notificationMngr2.notify(NOTIFICATION_ID, notification2);
locationHandler.postDelayed(this, distanceDelay);
}
}, distanceDelay);
}
It's just a snippet and the purpose is that in the background, when the screen is locked, this will loop every 10 seconds. And it does. Even when the phone is locked, but only for about 3 times. After 3 times the timer goes up and the phone vibrates less frequent (Doze feature in the way?).
Also, the phone does vibrate, but the location isn't updated. When I unlock the phone with the app in the foreground, the location is still at the place when I locked the phone. After a while (10 seconds) it updates. I use a marker on the map to check.
Again: it works when the phone is unlocked.
Now I'm trying to use a Service, a Service (Intent Service), or a Broadcast Receiver, and start a new Thread, but I don't know how and nothing is working.
Some of the last code I have contains a not functioning Broadcast Receiver and the most recent code contains a AlarmManager:
public void getLocation(Context context) {
AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(context, AlarmIntent.class);
PendingIntent pi = PendingIntent.getBroadcast(context, 0, intent, 0);
//After after 30 seconds
am.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, System.currentTimeMillis(), 10000, pi);
context.getSystemService(Context.CONNECTIVITY_SERVICE);
mMap.clear();
mMap.setMyLocationEnabled(true);
mMap.getUiSettings().setMyLocationButtonEnabled(false);
LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
String provider = locationManager.getBestProvider(criteria, true);
myLocation = locationManager.getLastKnownLocation(provider);
latitudeCurrentPosition = myLocation.getLatitude();
longitudeCurrentPosition = myLocation.getLongitude();
LatLng latLngCurrent = new LatLng(latitudeCurrentPosition, longitudeCurrentPosition);
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLngCurrent));
mMap.animateCamera(CameraUpdateFactory.zoomTo(distZoom));
currentPattern = shortTest;
showNotification(context);
mHereIAm = mMap.addMarker(new MarkerOptions()
.position(new LatLng(latitudeCurrentPosition, longitudeCurrentPosition))
.title(weAreHere)
.draggable(false)
.icon(BitmapDescriptorFactory
.fromResource(R.drawable.marker_iconv3)));
mHereIAm.setTag(0);
mHereIAm.showInfoWindow();
}
AndroidManifest permissions:
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="com.android.alarm.permission.SET_ALARM" />
But at the long of 10000, Android Studio is telling me "Value will be forced up to 60000 as of Android 5.1; don't rely on this to be exact..." etc. So an AlarmManager isn't useful either.
With the last code, my app isn't even running anymore.
But still: vibrations and stuff still occur, but location updates don't.
In short:
I need some basic (at least, I think it just can't be so difficult, as the only problem is that it's not working when the screen is locked) code, that updates my location on a certain, variable interval.
Maybe I have to use a Handler/Runnable, start a new Thread, use a Service or a Broadcast Receiver. Maybe an AlarmManager may work as well, but I don't know how and which to use.
This is my first post. If anything misses or you guys need more information, please ask. I'm trying to be as precise as possible, without using to much overhead.
Edit 01
Can I use a Job Service to do so? - I've updated the API to 21, so I can make use of this service, but I don't know if that's the right solution I'm looking for? Got some great tutorials for the use of it.
Edit 02
Let me be more clear with less overhead: I am looking for a solution to get the user's current location when the device is locked: with an API, a Service, an IntentService, a BroadcastReceiver, ... - every tutorial tells me something different, even here at Stack Overflow I have troubles with finding the right solution.
I was able to use a Service as well as an Intent Service, but I cannot request any location updates, because of some errors, like:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.name.name/com.name.name.MapsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.setMyLocationEnabled(b‌​oolean)' on a null object reference - searching for a solution for this error, gives me another error later on, and on, and on... I got myself stuck in an error-loop and a lot of unnecessary code.
I hope there is a simple way to get the user's location and you guys could help me. Thanks again.
Edit 03
I've followed the instructions on this tutorial and the location is checking. See the following code:
public class LocationService extends Service implements LocationListener {
private final Context mContext;
// flag for GPS status
boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
// flag for GPS status
boolean canGetLocation = false;
Location location; // location
double latitude; // latitude
double longitude; // longitude
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute
// Declaring a Location Manager
protected LocationManager locationManager;
public LocationService(Context context) {
this.mContext = context;
getLocation();
}
public Location getLocation() {
try {
locationManager = (LocationManager) mContext
.getSystemService(LOCATION_SERVICE);
// getting GPS status
isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
//isNetworkEnabled = locationManager
// .isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPSEnabled && !isNetworkEnabled) {
// no network provider is enabled
} else {
this.canGetLocation = true;
// First get location from Network Provider
if (isNetworkEnabled) {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
/**
* Stop using GPS listener
* Calling this function will stop using GPS in your app
* */
public void stopUsingGPS(){
if(locationManager != null){
locationManager.removeUpdates(LocationService.this);
}
}
/**
* Function to get latitude
* */
public double getLatitude(){
if(location != null){
latitude = location.getLatitude();
}
// return latitude
return latitude;
}
/**
* Function to get longitude
* */
public double getLongitude(){
if(location != null){
longitude = location.getLongitude();
}
// return longitude
return longitude;
}
/**
* Function to check GPS/wifi enabled
* #return boolean
* */
public boolean canGetLocation() {
return this.canGetLocation;
}
/**
* Function to show settings alert dialog
* On pressing Settings button will lauch Settings Options
* */
public void showSettingsAlert(){
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// Setting Dialog Title
alertDialog.setTitle("GPS is settings");
// Setting Dialog Message
alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");
// On pressing Settings button
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
// on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
// Showing Alert Message
alertDialog.show();
}
#Override
public void onLocationChanged(Location location) {
}
#Override
public void onProviderDisabled(String provider) {
}
#Override
public void onProviderEnabled(String provider) {
}
#Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
#Override
public IBinder onBind(Intent arg0) {
return null;
}
}
I've disabled Network location and only allowed GPS location for testing - tested both.
And my MapsActivity:
public void getLocation(){
gps = new LocationService(MapsActivity.this);
if(gps.canGetLocation()) { // gps enabled} // return boolean true/false
latitudeCurrentPosition = gps.getLatitude(); // returns latitude
longitudeCurrentPosition = gps.getLongitude(); // returns longitude
latLngCurrent = new LatLng(latitudeCurrentPosition, longitudeCurrentPosition);
Toast toastLatCur = makeText(getApplicationContext(), "Lat Current: " + latitudeCurrentPosition + "" ,Toast.LENGTH_SHORT);
toastLatCur.show();
Toast toastLongCur = makeText(getApplicationContext(), "Long Current: " + longitudeCurrentPosition + "" ,Toast.LENGTH_SHORT);
toastLongCur.show();
}
else {
gps.showSettingsAlert();
}
if(goToLocation){
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLngCurrent));
goToLocation = false;
if(firstStart){
mMap.animateCamera(CameraUpdateFactory.zoomTo(distZoom));
firstStart = false;
}
}
vibrateNotification();
}
When the screen is locked, the phone vibrates as I told in vibrateNotificatoin() - works perfectly every 10 seconds. But the location doesn't get updated! So a Service is not the right way to solve this. Help!
You should use the service to perform tasks which are needed to be done even when the application is not running. Give a try.

Why is this double null?

I' m in a service, and I just need the latitude and longitude. Just two doubles. So, I did the following:
LocationManager lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
if (ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
double longitude = location.getLongitude();
double latitude = location.getLatitude();
}
For some reason, the latitude and latitude are null. The documentation says this is possible if the information for location is unavailable, but it should be available, since I first check if the permissions are there in the if statement, right? In the phone that I am testing on, I do have location enabled. Why is the latitude and longitude null?
If you try this instead, what is the output?
locationManager.getLastKnownLocation(LocationManager.PASSIVE_PROVIDER);
It's because, even if location is enabled, there is no "lastKnownLocation" available yet. If you go to (for example) google maps app and ask for current location, after location is successfully fetched, go to your app and it will work (lat and lon != null).
EDIT: I don't know the code for android location service API, but for google maps API is something like this (i'm sure is similar):
public void methodThatUseLocation() {
if (ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(getActivity(), PERMISSIONS, MainActivity.REQUEST_LOCATION);
} else {
Location lastLocation = LocationServices.FusedLocationApi.getLastLocation(googleApiClient);
if (lastLocation != null) {
Double latitude = lastLocation.getLatitude();
Double longitude = lastLocation.getLongitude();
// do something with latitude and longitude
} else {
requestLocationUpdate();
}
}
}
private void requestLocationUpdate() {
if (ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(getActivity(), PERMISSIONS, MainActivity.REQUEST_LOCATION);
} else {
LocationServices.FusedLocationApi.requestLocationUpdates(googleApiClient, locationRequest, this);
}
}
The reason is, you are checking last known location, and if there were no locations previously fetched by this provider, all corresponding parameters will be null. Method getLastKnownLocation reuses information fetched by other apps/services, and it can happen that there were no information saved.
You can try to make single location update using method requestSingleUpdate, so you won't depend on your device state.

Android GPS incorrect location data on query

I am not using mock locations for this... In fact the code was working fine just last week.
I have an app that gathers GPS data and spits out a google maps link using X,Y coordinates generated by the application itself. I am not 100% sure why its not working the way it should be but when I request the app to make a google maps link based on the GPS location provided by the phone it tells me I am 5 - 6 blocks away from my point of origin (Where I actually am at the time) Not quite what I want it to do
Knowns:
I have the proper permissions set up
All of the code worked last week just fine
Here is the code to gather the GPS info:
Toast.makeText(context, "Gathering GPS Data...", Toast.LENGTH_SHORT).show();
gps = new gpsTracker(Settings.this);
if(gps.canGetLocation()){
try{
gps.getLocation();
lon = gps.getLongitude();
lat = gps.getLatitude();
Toast.makeText(getApplicationContext(), "Your location is - \nlat: " + lat + "\nlon: " + lon, Toast.LENGTH_LONG).show();
}
catch(Exception e){}
}
else{
gps.showSettingsAlert();
}
The class all of the above is pulling from:
import android.app.AlertDialog;
import android.app.Service;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.util.Log;
public class gpsTracker extends Service implements LocationListener {
private final Context mContext;
// flag for GPS status
boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
// flag for GPS status
boolean canGetLocation = false;
Location location; // location
double latitude; // latitude
double longitude; // longitude
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute
// Declaring a Location Manager
protected LocationManager locationManager;
public gpsTracker(Context context) {
this.mContext = context;
getLocation();
}
public Location getLocation() {
try {
locationManager = (LocationManager) mContext
.getSystemService(LOCATION_SERVICE);
// getting GPS status
isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPSEnabled && !isNetworkEnabled) {
// no network provider is enabled
} else {
this.canGetLocation = true;
// First get location from Network Provider
if (isNetworkEnabled) {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
/**
* Stop using GPS listener
* Calling this function will stop using GPS in your app
* */
public void stopUsingGPS(){
if(locationManager != null){
locationManager.removeUpdates(gpsTracker.this);
}
}
/**
* Function to get latitude
* */
public double getLatitude(){
if(location != null){
latitude = location.getLatitude();
}
// return latitude
return latitude;
}
/**
* Function to get longitude
* */
public double getLongitude(){
if(location != null){
longitude = location.getLongitude();
}
// return longitude
return longitude;
}
/**
* Function to check GPS/wifi enabled
* #return boolean
* */
public boolean canGetLocation() {
return this.canGetLocation;
}
/**
* Function to show settings alert dialog
* On pressing Settings button will lauch Settings Options
* */
public void showSettingsAlert(){
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// Setting Dialog Title
alertDialog.setTitle("GPS is settings");
// Setting Dialog Message
alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");
// On pressing Settings button
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
// on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
// Showing Alert Message
alertDialog.show();
}
#Override
public void onLocationChanged(Location location) {
}
#Override
public void onProviderDisabled(String provider) {
}
#Override
public void onProviderEnabled(String provider) {
}
#Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
#Override
public IBinder onBind(Intent arg0) {
return null;
}
From what is specified[difference of 4-5 blocks], you may be obtaining the location from networkProvider only.
With this gpsTracker code mentioned in the question,
there are a few modifications required, instead of using the code as it is:
1.
There are 2 if loops which verify the source of location is enabled or not and No 'else':
if (isNetworkEnabled) {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
This means the application is going to do twice the work when you can obtain the location from both sources. Further, the source of location obtained always remains ambiguous.
This is good when you just need approximate location which should not be null majorly.
If you want to use only this class to obtain location, try structuring the if-else according to requirement and ensuring that its not going to repeat if the location is obtained.
Eg. if GPS is on a higher preference, applies in your case, shift that if above and put the network condition with an else like:
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
} else if (isNetworkEnabled) {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
For your requirement, i suggest removing the network provider part and obtaining the location only from GPS, esp if line of sight is not a problem.
When your code was working fine, it must be fetching the location from GPS and setting it in the object. But because of the two "if" and no "else", you'l never know whether location obtained is from Network or GPS - you can check location.getProvider() inside the condition of canGetLocation()
2.
Also, you can log the message or prompt some action for one particular source...like:
In this part:
if (!isGPSEnabled && !isNetworkEnabled) {
// no network provider is enabled
}
just separate it into two different if(s) and code accordingly. As of now, nothing happens here so you wouldn't know if both are disabled unless you check it externally.
Suggestion: Try the LocationClient which uses GooglePlayServices for Retrieving Current Location . I have found it more reliable and useful. Check this Fused Location Provider example, setting LocationRequest object according to your requirement is the key.
Another update: just came across: useful ques on stack overflow - Good way of getting the users location
Update for anybody looking up this question/answer
Regarding the suggestion of LocationClient;
LocationClient is no longer found under com.google.android.gms.location, refer:
Android play services 6.5: LocationClient is missing
You should check out http://developer.android.com/guide/topics/location/strategies.html. There are some nice strategies to obtain accurate locations on this page. Here is some example code I've take from the site:
private static final int TWO_MINUTES = 1000 * 60 * 2;
/** Determines whether one Location reading is better than the current Location fix
* #param location The new Location that you want to evaluate
* #param currentBestLocation The current Location fix, to which you want to compare the new one
*/
protected boolean isBetterLocation(Location location, Location currentBestLocation) {
if (currentBestLocation == null) {
// A new location is always better than no location
return true;
}
// Check whether the new location fix is newer or older
long timeDelta = location.getTime() - currentBestLocation.getTime();
boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
boolean isNewer = timeDelta > 0;
// If it's been more than two minutes since the current location, use the new location
// because the user has likely moved
if (isSignificantlyNewer) {
return true;
// If the new location is more than two minutes older, it must be worse
} else if (isSignificantlyOlder) {
return false;
}
// Check whether the new location fix is more or less accurate
int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation.getAccuracy());
boolean isLessAccurate = accuracyDelta > 0;
boolean isMoreAccurate = accuracyDelta < 0;
boolean isSignificantlyLessAccurate = accuracyDelta > 200;
// Check if the old and new location are from the same provider
boolean isFromSameProvider = isSameProvider(location.getProvider(),
currentBestLocation.getProvider());
// Determine location quality using a combination of timeliness and accuracy
if (isMoreAccurate) {
return true;
} else if (isNewer && !isLessAccurate) {
return true;
} else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) {
return true;
}
return false;
}
/** Checks whether two providers are the same */
private boolean isSameProvider(String provider1, String provider2) {
if (provider1 == null) {
return provider2 == null;
}
return provider1.equals(provider2);
}

Categories