Android Studio suddenly cannot resolve symbols

Question

Android Studio 0.4.2 was working fine and today I opened it and almost everything was red and the auto-completion had stopped working. I look at the imports and AS seems to

Answer 1

Got the same problem today. Fixed it by changing the jdk location in the project structure from \java\jdk1.7.0_05 to \java\jdk1.7.0_25 (which I didn´t know existed until now).

I´m using Android Studio 0.8.6.