Android Studio Does Not Recognize Classes

All classes in Android Studio are icons below, and there is no red underline when you write the compilation error code, but you can debug the actual machine normally.
Could you tell me how to deal with this?

The version is as follows.
Android Studio 2.2.3 Operating System: Windows 7 64-bit Java 8

The same phenomenon occurs when you create a new project.
The gradle is as follows