I'm looking for an .jar or library project that will allow users of my application to easily send feedback from inside the application about their experience.
As asked in this question, I am looking for something similar to the crash reporting tool used in Google Plus, that allows the user to get in contact with me, besides leaving bad reviews.
Some not-quite there solutions that came up in answers to other questions:
Does a library like this exist? Is there an easy way to gather user feedback from within the application?
For a full-featured user support service, you can have a look to Capptain: http://www.capptain.com/
But with ACRA you can also trigger a report programmatically. You could call the method handleException(new UserRequestedException()) when the user selects an option in your preferences screen, for example.
You would then filter your ACRA reports spreadsheet for all stacktraces containing UserRequestedException.
UserRequestedException would be a custom Exception that you would implement.
The NOTIFICATION mode can be configured to display a form containing an e-mail field and comments field. The e-mail given by the user the first time is saved in the apps preferences.