Users hate to lose data, and it's a tough situation when it's a user error that leads to the loss. One solution, though, is a simple "undo" button, which can be a little bit difficult to implement on Android. So, here's a solution from Jens Driller: Android - UndoBar.
It's small and simple, and does exactly what it sounds like - a notification (modeled after Gmail's) that includes a message about the items deleted and an undo button - and it looks like this on pre-KitKat devices:
And like this post-KitKat:
Clean, easy to use, and good-looking. Check it out if you're interested in a simple yet useful solution, or if your users just keep accidentally deleting their stuff.