I have a problem related to the Location API.
I tried the following code:
LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
Location loc = getLastKnownLocation(LocationManager.GPS_PROVIDER);
loc is always null, when getLastKnownLocation() is called.
What is wrong?
Along with the permissions in your AndroidManifest.xml file, have you registered a location listener?
LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
Location loc = getLastKnownLocation(LocationManager.GPS_PROVIDER);
lm.requestLocationUpdates(LocationManager.GPS, 100, 1, locationListener);
Then have a method, in this case locationListener, to complete your task
private final LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
If you're running the code in the emulator, any calls to get the GPS location will return null until you explicitly update the location (via Eclipse or ADB).
I had the same problem as you, I always receive a null Location object, But finally it was solved in an easy way. You must have a valid GPS location, so, if the GPS is not enabled and you dont't have enough signal, the Location object will be ALWAYS null.
Have you set the permissions in your AndroidManifest.xml? You need these permissions in order to access the user's location with an application:
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION" />
Here's something you can use:
LocationManager lm = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
String bestProvider = lm.getBestProvider(criteria, false);
Location loc = lm.getLastKnownLocation(bestProvider);
last_lat = loc.getLatitude();
last_lng = loc.getLongitude();
You need the instance Of LocationManager like this:
First Instance:
LocationManager lm = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
Wrong:
Location loc = getLastKnownLocation(LocationManager.GPS_PROVIDER);
Correct:
Location loc = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
Related
I'm using the following code to get my last know location, but it is not working
LocationManager locationManager = (LocationManager)getSystemService(LOCATION_SERVICE);
Criteria criteria = new Criteia();
String provider = locationManager.getBestProvider(criteria, true);
Location location = locationManager.getLastKnownLocation(provider);
if(location!=null){
onLocationChanged(location);
}
locationManager.requestLocationUpdates(provider, 20000, 0, this);
Hard to say given the lack of error information. Just a guess ... do you have these in AndroidManifest.xml:
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
I have a simple location manager that normally works, however when the Android device has been turned off and then turned back on, the android location manager returns Null even when I have it requesting updates. I am aware that getLastKnownLocation can return null, however I believe I am handling that in my code. All suggestions Appreciated.
Apparently lon = location.getLongitude(); is crashing it.
LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location == null)
{
// request location update!!
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
lon = location.getLongitude();
lat = location.getLatitude();
}
mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
//Get last known location
location = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
//Update if not null
if (location != null)
{
lat = location.getLatitude();
lon = location.getLongitude();
}
//Request update as location manager can return null otherwise
else
{
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
lat = location.getLatitude();
lon = location.getLongitude();
}
}
the android location manager returns Null even when I have it requesting updates
Correct. Requesting updates requests that Android start trying to find out where the device is. That will take a while. In the meantime, getLastKnownLocation() can very well return null.
getLastKnownLocation() is generally only useful if you would like to know the location, but if that data is not ready, you can move on without it. If you need the location, and getLastKnownLocation() returns null, you will to wait to use the Location until onLocationChanged() is called. Note that onLocationChanged() may never be called, as there is no requirement that the user have any location providers enabled, and there is no requirement that the device be in a position to actually get location fixes.
I saw your reply on the airplane mode but you do however have bad practices in your code.
LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location == null)
{
// request location update!!
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
lon = location.getLongitude();
lat = location.getLatitude();
}
you already saw here that location in null, that means that you can't access the inner properties such as latitude and longitude. In any case, location requests are asynchronous and it takes a short amount of time for them to start.
mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
//Get last known location
location = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
//Update if not null
if (location != null)
{
lat = location.getLatitude();
lon = location.getLongitude();
}
//Request update as location manager can return null otherwise
else
{
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
lat = location.getLatitude();
lon = location.getLongitude();
}
}
Even here, in the "else" clouse, you can't access the location right away. that means that you can't immediately get the location (it will just hold the last value).
What you should do is implement the onLocationChanges method and hadle the location there in asynchronous way. like this:
LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null)
{
lat = location.getLatitude();
lon = location.getLongitude();
}
else
{
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
}
}
#Override
public void onLocationChanged(Location location) {
lat = location.getLatitude();
lon = location.getLongitude();
}
The only problem was that I had airplane mode enabled on the Android Phone. I'm a bit embarrassed now!
I'm trying to get the exact longitude and latitude of a android device. The problem is that when setting data in google maps, I realize that the position is not correct. I think the device is getting any previously saved position
LocationManager locationManager;
String svcName = Context.LOCATION_SERVICE;
locationManager = (LocationManager)getSystemService(svcName);
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setPowerRequirement(Criteria.POWER_HIGH);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setSpeedRequired(false);
criteria.setCostAllowed(true);
String provider = locationManager.getBestProvider(criteria, true);
Location location = locationManager.getLastKnownLocation(provider);
updateWithNewLocation(location);
locationManager.requestLocationUpdates(provider, 2000, 10, locationListener);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
Log.i("lon", longitude+"" );
Log.i("lat", latitude+"");
}else{
Log.i("Null", "Es nulo");
}
LocationListener
private final LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
updateWithNewLocation(location);
}
public void onProviderDisabled(String provider) {
updateWithNewLocation(null);
}
public void onProviderEnabled(String provider) {}
public void onStatusChanged(String provider,int status,Bundle extras){}
};
xml
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_GPS"/>
<uses-permission android:name="android.permission.ACCESS_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_ASSISTED_GPS"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
How can I fix it?? I need the current position of teh devices
The line:
Location location = locationManager.getLastKnownLocation(provider);
delivers the last know, even if that location is from yesterday.
Remove the line, cnage the code appropriate, and wait till you get an location event in onLocationChanged().
Further you may check: the timestamp of the location: caluclate the difference to current time and you know if it is a recent location.
Further check location getHoricontalAccuracy() (or named similar) if it is above 40m ignore the location.
i want to get current coordinates, i try next
GoogleMap gm=getMap();
gm.setMyLocationEnabled(true);
Location location=getMap().getMyLocation();
But getMap() returns null,
and i try :
Criteria criteria = new Criteria();
String provider = service.getBestProvider(criteria, false);
Location location = service.getLastKnownLocation(provider);
if (location.getLatitude()!=0){
LatLng userLocation = new LatLng(location.getLatitude(), location.getLongitude());
But this work's in Android 2.3, but in 4.2. it returns null.
I have pretty much the same code in my app and it works well on version 4 :
String provider;
LocationManager locManager = (LocationManager)
getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locManager.getBestProvider(criteria, false);
Location location = locManager.getLastKnownLocation(provider);
if (location != null) {
latitude = location.getLatitude();
mLongitude = location.getLongitude();
}
But your problem must be related to your getMap() error. What exactly is the error message ?
The location properties are reset when the phone is rebooted.
So if the device hasn't requested a new location by any means(Maps or any other apps that request a location), getMyLocation will return null.
What you should do, if getMyLocation returns null, is to request a new Location.
Here is a thread on how to get/request a location:
Good way of getting the user's location in Android
Look for the requestLocationUpdates() method.
Then when a location has been found(It can take some time...especially indoor), the callBack OnLocationChanged is called with the new location in parameter.
Hope this helps!
as the title i have a question about the gps api
follow is my code
LocationManager loctionManager;
String contextService=Context.LOCATION_SERVICE;
loctionManager=(LocationManager) getSystemService(contextService);
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(true);
criteria.setPowerRequirement(Criteria.POWER_LOW);
String provider = loctionManager.getBestProvider(criteria, true);
Location location = loctionManager.getLastKnownLocation(provider);
double a=location.getLatitude();
double b=location.getLongitude();
Log.d(""+a,""+b);
then the error is java.lang.NullPointerException
anyone can help me?thx
getLastKnownLocation() can return null you need to ensure it does not.
In order to get a Location you need at first to set permission in your Manifest.
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
Then in your code you need to listen for location avalability. You do that by registering a LocationListener. The activity will display, and when Android will have a location for you it will call you back.
private final LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
latitude = location.getLatitude();
longitude = location.getLongitude();
//Do what you want with your coordinates
}
loctionManager.requestLocationUpdates(LocationManager.GPS, 100, 1, locationListener);
If you are using the emulator and not a real device you need to force a location, you can use DDMS inside Eclipse to send a fake location: