We had this teacher in uni that was teaching several lectures and one of them being mobile computing ( actual name, but it was just android dev).

So on the first lecture he started to add a single button on the screen and trying to add an onClick functionality. But once he started to write the code he got errors (didn't include Button) and said to everyone:
"Ok, this is normal and now when I click on IDEs save button this will go away" ofc it didn't go aways.

So after 5 minutes of trying to write the full code from head he just opened another project and copied the code he need and tried to run the app (it crashed).

So after about 2/3 of a lecture I stopped laughing and went over to his desk and just hit alt+enter to import the lib and built the project without errors :D

Never went back to those lectures but I passed the class with highest grade by just demonstrating an app I built for fun without any proof that it is actually mine.