Do something when phone reaches a set of location?

Question

I have a list of coordinates in the database identified as POI. For a city could be >100 records.

I would like to get notified when the phone gets in 150 meters range of one of the location. The location coordinates too has an error/radius, usually 10 to 100meters. Since I don't find it good to add each location(could be hundreds) for a trigger, how can I optimize the wake-up code?

Also do I have options to remove a previously setup notification from the queue?

Answer 1

You could store your POIs in some sort of intelligent Hash-Table using the coordinates to compute a unique hash. Each time a location update arrives you make a lookup in your hash-table to see if there are POIs near the current location. This lookup should only take O(1), since it is a hash-lookup.

The desired range should be taken into account when computing the hashes and storing the POIs.

Just an idea!

Kind regards, mefiX