lastLocation is null
06 March, 2019 - 3 min read
There was a requirement to fetch nearby data by sending the devices latitude and longitude to a rest endpoint. The location itself wasn’t trivial so an approximate location of the city would be good enough for my use case.
tldr: Next time you lastLocation is null, check what permission you are asking for.
After looking around in the Android documentation I decided to use the new Fused Location Provider Google is promoting. That is for devices that have Play Services installed.
The API would get me a location which the OS has cached when any app has requested the location before which is usually the case with so many apps requiring location data.
Since I wasn’t looking for an exact location I thought to myself let’s just ask for the COARSE_LOCATION permission and not the FINE_LOCATION permission. So I added it to the manifest and setup the required checks to get the location.
It was working half the time. Half the time there was a location, half the time there wasn’t.
The first think I thought was that my emulator has problems, so I tried it on an actual device, where it worked again, half the time. My initial assumption was that there could be no apps requesting a location on the system so I would be the first one, hence the null location when requesting the lastLocation.
Creating this whole location listening logic was something I was not keen on doing. Fire up a request, listen for a location, then stop the updates etc, it was too much work for just one lousy location!
Maybe something else was wrong. I opened Google Maps and then requested the location on the map so it would have a valid location. I opened then my app, but, it the lastLocation was null again!
Frustrated and ready to implement my own location request service so I don’t need to depend on the lastLocation.
Then it hit me!
I am not sure why I did what I did, but I changed the permission from COARSE to FINE. Since FINE_PERMISSION includes COARSE_PERMISSION I didn’t need to have both inside the manifest file.
Press run on the device, and voila, I had a location. Even on the emulator. Every time!
Turns out it makes sense, the vast amount of Android apps use FINE location to pinpoint the user which the Play Services will cache. Not many apps create a location request for the COARSE location.
In conclusion I was listening for a lastLocation which was retrieved by the WiFi or cellular provider but not GPS. When this is not available the lastLocation will be null. Although if you ask for FINE_PERMISSION then it will get location data from all of the above sources
Here you have it, next time you lastLocation is null, check what permission you are asking for.