If you want to add missing import statements then in Eclipse we use,
Windows : Ctrl + Shift + O
Mac OS X : Command + Shift + O
For Intelij the Shift key is replaced by Alt key,
Intelij IDE Android Studio
Windows : Ctrl + Alt + O
Mac OS X : Command + Alt + O
Note : If you see that this does not work, then follow these steps,
1. Go to Android Studio -> Preferences
2. Select Editor -> Auto Import
3. Under Java, Check Optimize imports on the fly and Add unambiguous imports on a fly
4. Apply the changes.
Thats it!! If you know any good tricks for developers who have just moved from Eclipse to Intelij do write then down in the comment box.