I have a method which registers a listener and requests location updates. I would like to the location coordinates in the current method itself, not in the onLocationChanged method.
My code is:-
myclass {
onCreate {
location_Manager = (LocationManager) getSystemService (Context.LOCATION_SERVICE);
locLstnr = new myLocationlistener();
locMgr.requestLocationUpdates(LocationManager.GPS_PROVIDER, Loc_listener.MINIMUM_TIME_BETWEEN_UPDATES, Loc_listener.MINIMUM_DISTANCE_CHANGE_FOR_UPDATES, locLstnr);
}
class myLocationListener () {
onLocationChanged() { ... }
onProviderDisabled() { ... }
onProviderEnabled() { ... }
}
}
I know i can get getLastKnownLocation() , but incase it is not available, isn't it possible to get the location at all? This and this are a similar questions, but doesn't help me. I don't have problems with using onLocationChanged method, but i need to have the location in the onCreate method. Is that possible? One way might be to store the location onto a variable in the myLocationListener and access it, but is there an alternative or a better solution?
I think if getLastKnownLocation() gives null then you have to wait for call back....
just can do can make request for update
locationManager.requestLocationUpdates(locationProvider, 0, 0, locationListener);
http://devdiscoveries.wordpress.com/2010/02/04/android-use-location-services/
from link
getLastKnownLocation() is faster after a connection has been established with the GPS satellite. For the first time, it will return null, or no value till no connection is established. You can add a GpsListener to know when the location is obtained. Search about "how to get a gps fix" and you might get answer to your question
and refer link
Related
I have written this function for requesting location updates:
private void RequestLocations() {
locationListener = new LocationUpdater();
lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
if (!lm.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,0,
100, locationListener);
} else {
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 100,
locationListener);
lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,0,
100, locationListener);
}
}
I am calling this function in the onStart() of a service which I have made a foreground service.
In locationUpdater I have implemented locationListener. In on location changed I am toasting lat/lang.
It is working fine if I am at a walking speed.
But while I am driving it is not as accurate and fast as it was with walking speed. Even though it is not toasting any location if I am at a speed of more than 50 KM/h and as soon as I stop it again starts working and toast a new location.
I wanted to make something in which as soon as I move 100 meters away it should toast new location whatever the speed is.
Please guide me and if I am wrong at any place make me correct.
I'm trying to find a way to turn off the GPS immidietly in case a good enough location was found, while still having a time limit to "give up".
I tried to do this with the following strategy:
start checking for locations, as soon as a location that has an accuracy lower than the maximum tolerated, pass it to the next function for processing and stop looking for updates.
Also, to save battery life, if such location could not be found in 30 seconds, stop looking for location updates without passing a value (basically give up, and hope to better luck next time).
To count the 30 seconds, I'm using a handler. But as soon as I write the line locationManager.removeUpdates(locationListener); in the handler, the locationListener in the parenteses in both lines (the one in the handler and the one in the listener) turns red and reports an error: The local variable locationListener may not have been initialized
Here is my code:
private void checkProximity() {
final LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
//start tracking location
final LocationListener locationListener = new LocationListener() {
...
#Override
public void onLocationChanged(Location location) {
//if new accuracy is better than the best estimate - update the best estimate
if(location.getAccuracy() < MAXIMUM_TOLERATED_ACCURACY) {
//forward location to scanProximity and end the location search
scanProximity(location);
locationManager.removeUpdates(locationListener); //FIRST LINE (see below)
}
}
};
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,
500, 0, locationListener);
Handler h = new Handler();
int delay = 30 * SECOND;
Runnable removeListener = new Runnable() {
#Override
public void run() {
//if this code is reached - the maximum tolerated accuracy was not met in the period time
//extended to find a location
//TODO stop the location manager and return without forwarding a value
locationManager.removeUpdates(locationListener); //as soon as I write this line, the FIRST LINE and this line turns red.
}
};
h.postDelayed(removeListener, delay);
}
Is there anyway I can do this differently so I won't get an error?
I recommend you use Little Fluffy Location Library to work with GPS locations. Check out the examples codes and see which makes you more easy the solution to your problem , this is a beautiful way.
I am trying the 'LocationUpdates' sample from http://developer.android.com/training/location/receive-location-updates.html . This application gets and prints location notifications.
I am trying to change the interval of the location updates according to my latest location.
So - I had added mLocationRequest.setInterval() into onLocationChanged
The result is very wrong. My application is bombarded with many location updates (few a second!!!!)
My only change to the sample is this:
private int x=0;
#Override
public void onLocationChanged(Location location) {
// Report to the UI that the location was updated
mConnectionStatus.setText(R.string.location_updated);
// In the UI, set the latitude and longitude to the value received
mLatLng.setText(String.valueOf(x++));
mLocationRequest.setInterval(1000); // Change 1
mLocationClient.requestLocationUpdates(mLocationRequest, this); // Change 2
}
How can I change the interval inside onLocationChanged ?
I think that the problem is that requestLocationUpdates resets the last request, and then immediately sends another notification. so a loop is created. (faster than the fastest interval). so I need a reliable way to change the interval of a 'live' LocationRequest
You are not supposed to call mLocationClient.requestLocationUpdates(mLocationRequest, this); inside onLocationChanged(Location location)
since you are registering the listener again, and you will get the first call immediately.
so what i would do would be:
dont call mLocationClient.requestLocationUpdates(mLocationRequest, this); and see if anyways mLocationRequest.setInterval(1000); is taking effect
if this doesnt work, try to unregister the listener, and then use a trick to wait before registering it again with the new settings, something like:
Handler h = new Handler();
#Override
public void onLocationChanged(Location location) {
//... all your code
mLocationRequest.setInterval(1000);
mLocationClient.removeLocationUpdates(LocationListener listener)
h.postDelayed (new Runnable(){
public void run(){
mLocationClient.requestLocationUpdates(mLocationRequest, YOUROUTTERCLASS.this);
}
}, 1000);
}
So during one second there is not registered listener, so you wont get any updated, and after that, the listener is registerered with that interval.
Try using mLocationRequest.setFastestInterval(long millis)
As mentioned in developer.android.com :
This allows your application to passively acquire locations at a rate faster than it actively acquires locations, saving power. Unlike setInterval(long), this parameter is exact. Your application will never receive updates faster than this value.
Try to use :
mLocationRequest.requestLocationUpdates("gps", 1000, 0, this);
However I don't agree to do a requestLocationUpdates in onLocationChanged event; In my opinion should be setted outside onLocationChanged Event...
Can I use the same locationManager for requesting updates for the gps and network provider, or should I create two locationManagers and separate onLocation changed functions etc. I got really confused about this
You will want to check and see which one is available in the order you want to use them and then use the corresponding one:
if(mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, LOCATION_UPDATE_MIN_TIME, LOCATION_UPDATE_MIN_DISTANCE, locationListener);
}
else if(mLocationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)){
mLocationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, LOCATION_UPDATE_MIN_TIME, LOCATION_UPDATE_MIN_DISTANCE, locationListener);
}
You can use the same listener because all the listener's methods take as a parameter a Location object which is source agnostic:
#Override
public void onLocationChanged(Location location) {
// updateLocation();
}
My app checks at a specific time whether a user is at a given location. I use the alarm manager to start a service that makes this call:
locationManager.requestLocationUpdates(bestProvider, 0, 0, listener);
And also checks:
locationManager.getLastKnownLocation(bestProvider);
But I'm having problems when running on a real device. For one thing, getLastKnownLocation is most likely the last place the GPS was on, which could be anywhere (i.e., it could be miles from the user's current location). So I'll just wait for requestLocationUpdates callbacks, and if they aren't there within two minutes, remove the listener and give up, right?
Wrong, because if the user's location is already stable (i.e., they've used GPS recently and haven't moved) then my listener will never be called because the location doesn't change. But the GPS will run until my listener is removed, draining the battery...
What is the right way to get the current location without mistaking an old location for the current location? I don't mind waiting a few minutes.
EDIT: It's possible that I'm wrong about the listener not being called, it may just take a little longer than I thought... Hard to say. I'd appreciate a definitive answer still.
The code may be something like that:
public class MyLocation {
Timer timer1;
LocationManager lm;
public boolean getLocation(Context context)
{
lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListenerGps);
timer1=new Timer();
timer1.schedule(new GetLastLocation(), 20000);
return true;
}
LocationListener locationListenerGps = new LocationListener() {
public void onLocationChanged(Location location) {
timer1.cancel();
lm.removeUpdates(this);
//use location as it is the latest value
}
public void onProviderDisabled(String provider) {}
public void onProviderEnabled(String provider) {}
public void onStatusChanged(String provider, int status, Bundle extras) {}
};
class GetLastLocation extends TimerTask {
#Override
public void run() {
lm.removeUpdates(locationListenerGps);
Location location=lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
//use location as we have not received the new value from listener
}
}
}
We start the listener and wait for update for some time (20 seconds in my example). If we receive update during this time we use it. If we don't receive an update during this time we use getLastKnownLocation value and stop the listener.
You can see my complete code here What is the simplest and most robust way to get the user's current location on Android?
EDIT (by asker): This is most of the answer, but my final solution uses a Handler instead of a Timer.
If the user's location is already stable, then getLastKnownLocation will return the current location. I'd call getLastKnownLocation first, look at the timestamp (compare Location.getElapsedRealTimeNanos() with SystemClock.elapsedRealTimeNanos()) then register a listener if the fix is too old.