Preventing reverse engineering of Urls used in Android app for HTTP Requests

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http://stackoverflow.com – I am designing an app that requests data from my server using a HTTP Connection. This data depends on the selected item so I have different urls on my server corresponding to the item chosen. For now I have hardcoded the Urls in the app, I am new to Android so my question is : How can i prevent reverse engineering of these urls? Thank you. (HowTos)