tl;dr: how to "undo" an erroneous click on "Do not show again" in Android studio?
When I fire up Android Studio (installed using umake on Ubuntu 14.04) I used to get a warning message telling me to change my JDK from OpenJDK to Oracle JDK. I decided today to fix this and, accidentally, the first thing I managed to do was to click "don't show this warning again" on Studio :-/
So now I think I've fixed the problem, but given that there seems to be several competing ways of telling studio to use a given JDK (setting an environment variable, changing Ubuntu's default java etc) I now want to make sure that I've solved it so I want to make studio give me the warning back! Either that, or a way of determining precisely which of my javas studio is using.