I want to develop a location based app.

Requirement: user inserts data(lat-long) and it is stored in SQLite. When user reach at that location he/she will get an alert. I want to define some area(e.g. 1 km) near to this location.
If user is in 1 km circle of this location then he/she get an alert.

I know how to use location listener but do not have idea to fix this area of circle.

I looked at [this](https://stackoverflow.com/questions/3695224/android-sqlite-getting-nearest-locations-with-latitude-and-longitude) but no idea how to use it.

Anybody can suggest me ? Thanks