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:
Related
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!
I am using the following code to determine the current location when a proximity alert fires:
Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location == null) {
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location == null) {
// We'll just write an empty location
location = new Location("");
}
}
When I look at the locations that I get back I get entering alerts in locations where I should't get them. I was under the impression since proximity alerts internally poll the GPS and network provider - thus updating the LastKnownLocation - that this code would yield the current location. Is this assumption correct?
I am using the following code to determine the current location and its working too. Check out dis code...
LocationManager locationManager;
String context = Context.LOCATION_SERVICE;
locationManager = (LocationManager) getSystemService(context);
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 = locationManager.getBestProvider(criteria, true);
if (null != provider)
{
Location location = locationManager.getLastKnownLocation(provider);
if (null != location) {
GpsFound=true;
currentLat = location.getLatitude();
currentLon = location.getLongitude();
System.out.println("Current Lat,Long :"+currentLat+" ,"+currentLon);
}
else
{
//GpsFound=false;
gpsMsg="Current Location can not be resolved!";
}
}
else
{
gpsMsg="Provider is not available!";
//GpsFound=false;
}
I would like to know how can I get location from the best provider
do I have to make two separate criteria 1 for the GPS and 1 for the network or is there a way to put them all together ?
this is my code when I add the COARSE criteria the GPS does not go on (no GPS flashing logo on the top of the screen) and when I use the FINE criteria I dont get any thing from the network.......so do I have to write criteria for both and switch between them for what ever is available or can they both be in the same criteria ?
because I have the "getBestProvider(criteria, true);" in my code so it should get the location from the best provider....right..??!
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
//// criteria.setAccuracy(Criteria.ACCURACY_COARSE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(true);
criteria.setPowerRequirement(Criteria.POWER_HIGH);
String provider = locationManager.getBestProvider(criteria, true);
Using a getBestProvider with Criteria.ACCURACY_FINE will never return the NETWORK_PROVIDER, even though wifi position is usually quite accurate.
In my application, I use getProviders to get all providers matching my criteria, then add the NETWORK_PROVIDER if it is activated and not yet in the list.
Then I launch a requestLocationUpdates for each of these providers, making sure to call removeUpdates when I get a location accurate enough.
This way, if the location provided by the network is accurate enough, the gps provider will be turned off
#nicopico getBestProvider with Criteria.ACCURACY_FINE can return the NETWORK_PROVIDER if gps is not enabled
i use the following code in my app
public void getLocation() {
// Getting Google Play availability status
int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(context);
// boolean network_enabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
// Showing status
if (status != ConnectionResult.SUCCESS) { // Google Play Services are not available
Log.e(TAG, "getLocation fired Google Play Services are not available");
mHandler.post(new UiToastCommunicaton(context.getApplicationContext(),
context.getResources().getString(R.string.gpserv_notfound)));
}
// Getting LocationManager object from System Service LOCATION_SERVICE
locationManager = (LocationManager) context.getSystemService(IntentService.LOCATION_SERVICE);
if (!locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {//check if network location provider context on
Log.e(TAG, "network location provider not enabled");
} else {
criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(true);
//criteria.setPowerRequirement(Criteria.POWER_LOW);
// Getting the name of the best provider
provider = locationManager.getBestProvider(criteria, true);
// Check provider exists then request for location
if (provider != null) {
requestLocation(locationManager, provider);
} else {
//start wifi, gps, or tell user to do so
}
}
}
public void requestLocation(LocationManager locationManager, String provider) {
Log.e(TAG, "requestLocation fired getting location now");
if (provider != null) {
locationManager.requestLocationUpdates(provider, 0, 0, this);
//locationManager.requestLocationUpdates(provider, 0, 0, this, Looper.getMainLooper());
} else {
//tell user what has happened
}
}
this code is in a class that implements locationListener
you can edit this line
locationManager.requestLocationUpdates(provider, 0, 0, this);
to reflect your implementation of locationListener
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);