One way is to use Google - Google has a Geo-coding REST service that you can leverage that returns address based on lat/longitude. What you would do is to treat it like a JSON data service (there is a new blog article on blogs.oracle.com/mobile on consuming JSON data services). In other word, create a URL connection to the Google Geolocation service. You would then need to write Java code to call the Google Geolocation service by using RESTServiceAdapter APIs. You can pass in the lat/longitude to the Google Geolocation JSON API, and it would return you an address.
Let us know if this is not sufficient - we will try to create a sample if needed.