I just need to understand this clearly, getLastLocation() method will give me the last known location and requestLocationUpdates will give me the current location every period of time.
now, i am developing a simple app to track mobile phones, which will be in cars.
my Question are :
1- how exactly getLastLocation() works, will this last known location be updated when the location change
2- which is better, using getLastLocation() to have the initial location then update the current location by using the method onLocationChanged or using requestLocationUpdates to have an up to date location every n sec ?
getLastLocation gives you the last location which was there in LocationClient, it can be null sometimes, say if you don't have any other application installed which uses location services, that's a rare case as most phones have Google maps or some other location dependent apps installed.
getLastLocation is only helpful, when you want location for once and your done with it, but for location updates you should use requestLocationUpdates, and using a service, your application will always get notified, when the location changes.
I hope you are using the FusedLocation Provider from play services, so you can specify how fast location updates you need, to check cases of battery drain and performance.
Also to note here when you use requestLocationUpdates then only you will get any location change updates.
so according to android docs getLastLocation() :-
Returns the best most recent location currently available. If a
location is not available, which should happen very rarely, null will
be returned. The best accuracy available while respecting the location
permissions will be returned. This method provides a simplified way to
get location. It is particularly well suited for applications that do
not require an accurate location and that do not want to maintain
extra logic for location updates.
This is the problem with getLastLocation(),that it is not accurate and it may return null if it does not have any last known location in cache.I have faced this issue many times in my application.So for getting the accurate location you should use requestLocationUpdates() but define the interval according to your need at which time interval you want the updates as a very short time span may cause more power usage.
Related
I've read some questions about this, but I didn't quite find an answer that I needed. I want to understand how getLastLocation works internally. How last known location cached value is updated?
We have requirement where we need to get last known location of the device. Can anyone explain how getLastLocation works? I have seen that getLastLocation API returns null even if location-setting is ON. At the same time if I checked Google Map app and it is able to get the location (of-course it must be using requestLocationUpdates or any other API).
On my Nexus-5, I observed that getLastLocation returns null even after I launch Google Map app and then launch my app again. Even if location is detected correctly in Google Map app, getLastLocation API returns null.
How Android system updates the last known location? Does it update only when some app requests for location via requestLocationUpdates API?
If Android system updates the last known location automatically then why do getLastLocation API returns null?
getLastLocation API
Getting last known location
Points to be noted:
Location permission is granted.
Location Setting is ON
Same code works on few devices, but fails on few devices.
I am trying to get location from Google's FusedLocationProviderAPI and Android Framework LocationManager API.
I have checked all existing questions on Stackoverflow
It would be great if anyone can explain under what circumstances getLastLocation API can return null even if location setting is ON. Does anyone know how this works internally?
getLastLocation : This method will give you the last location available on your device.
In some cases if your device don't have any last location then it will return null.
You should use onLocationChanged method for current location.
Please see example here you will get it
https://developer.android.com/training/location/receive-location-updates.html
According to doc
public abstract Location getLastLocation (GoogleApiClient client)
Returns the best most recent location currently available.
If a location is not available, which should happen very rarely, null
will be returned. The best accuracy available while respecting the
location permissions will be returned.
This method provides a simplified way to get location. It is
particularly well suited for applications that do not require an
accurate location and that do not want to maintain extra logic for
location updates.
Hope these help you.
I'm new with the Google's Fused Location API and I would like to know if there is any way of requesting a location update in any given time?
I know about setInterval() and setFastestInterval() but For example: If the user presses a button, can I get THE current location and not the last known? I just don't want to have the app working at very short intervals to conserve battery.
Thanks
getLastKnownLocation() only returns the last fix. So if no location providers are being updated the return value of getLastKnownLocation() will not change. The location object will also provide you with accuracy and time of the fix.
I would look at this post for more information. You could use some version of the one shot location.
http://android-developers.blogspot.com/2011/06/deep-dive-into-location.html
I've been working on an app that needs to be location-aware, and I've noticed that there are two (or more) methods of receiving location: with Google Play services (as seen here developer.android.com/training/location/retrieve-current.html#GetLocation) and with Location Manager, Providers etc. (as seen here http://www.vogella.com/tutorials/AndroidLocationAPI/article.html#locationapi_criteria).
What is the difference between these methods (if there is any)? Which one is more accurate?
edit: ok, I see that I sent the wrong link on the first thing. Won't this code (http://developer.android.com/training/location/receive-location-updates.html) give me location updates? Generally, what's the most accurate way to get my location?
The one with the GPS is accurate and that which is based on Network is not. Google Play Service use FUSE api to get the GPS location first, if the location is found (that's great), otherwise it will try to get location fix from Network Tower. In Short the one with GPS is accurate
The first method provides the details of LastKnownLocation. ie. the last location received from GPS or network provider when you or other apps accessed the location services. After that there are chances you moved a lot and it need not be your current location. So if You are planning to create an application that requires accurate location tracing, You should fetch the location as in the "Vogella" method. If the current location is unavailable, you can try using the last known location (As a plan B :-)).
I am developing an android application wherein I need the user location updates pretty frequently. Say 2 times a minute.
Earlier I had been using Google Play Service's "Fused location service" but the location updates were not received as requested.
The location updates got stuck for sometime, the interval between updates jumped to 10min or so.Sometimes even if I put my priority to "PRIORITY_HIGH_ACCURACY" the same happened.
I then went back to the old "Location Manager" and when I used the "NETWORK_PROVIDER", I noticed that the location updates got stuck due to this provider. Also the GPS does not get activated immediately, it takes some time. I am trying to build my custom fused location provider. How can I efficiently switch between providers, without getting lags on location updates.
I want to know what are the best practices for getting location updates regularly, all the time, be it either NW, GPS or both. Like it should work for an application where location updates getting stuck cannot be afforded.
Battery drain is not an issue for me right now.I am aware of all the supporting docs that Google provides regarding location access.
Any help would be much appreciated.
Thankyou !
FusedLocationProvider really is the best option for obtaining locations at the moment, because it uses a lot more than just GPS or Network data to obtain location fixes. I have experienced issues regarding intervals being missed as well, but ultimately this is something down to luck depending on availability of GPS, Network, etc. etc.
My favourite usage of FusedLocationProvider so far is in conjunction with the AlarmManager class: Basically, the idea is to start location tracking at intervals specified by the Alarm Manager (this can be set to every 30 seconds such as in your case). Once the interval is hit, the location provider is to obtain a location fix as soon as possible (so in the setInterval method or whatever it's called, the parameter is a 0). This way, you can avoid having to wait another 30 seconds for a new location, instead having the location tracker attempt to provide a location as soon as possible after the interval specified by the Alarm Manager is hit.
By the way, when making custom location tracking wrappers, be careful of using the .getLastKnownLocation() method as it only uses cached locations - you could end up sending the same location to the user every 30 seconds.
Good luck!
I'm using
myLocation = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
to retrieve the current location at the start-up of my application.
As the Android documentation states, this location can be "out-of-date", since the method returns the location when the GPS was used the last time.
How can I actively request the current location from the GPS? I thought about using LocationListener, however that might be a bit of an overkill, since I only need the location once (at the start of my app).
Any ideas?
Your initial intuition is correct - you need to use a LocationListener to request updates. Given that you require only a single position, you can unregister the LocationListener after the first value returns.
In practice though, it's probably wise to listen for a little bit longer. Location Based Services (particularly GPS) have a tendency to 'jump around' a bit when they first get their fix. Your best bet is to listen for a set amount of time, or a set number of updates, or until a certain level of accuracy has been achieved (the Location Listener will return the accuracy of the position returned).