Android Studio - Auto complete and other features not working

Solution 1:

Go File > Invalidate Caches / Restart... > Click at Invalidate an Restart

This really works for me.

Source: https://code.google.com/p/android/issues/detail?id=61844#c4

Solution 2:

You can also check if Power Save Mode on File menu is disabled.

Solution 3:

Close Android Studio Go to C:\Users\UserName.android and rename the folder:

• build-cache to build-cache_old

Go to C:\Users\UserName.AndroidStudio3.x\system OR (Android studio 4 and Higher) Go to C:\Users\UserName\AppData\Local\Google\AndroidStudio4.x and rename these folders:

• caches to caches_old

• compiler to compiler_old

• compile-server to compile-server_old

• conversion to conversion_old

• external_build_system to external_build_system_old

• frameworks to frameworks_old

• gradle to gradle_old

• resource_folder_cache to resource_folder_cache_old

Open the Android Studio and open your project again.

Solution 4:

1. Close Android Studio

2. Go to c_users_path_on_windows/.AndroidStudio3.5/system/

3. Delete the cache folder

4. Start Android Studio

   This works for me.

Solution 5:

Most of the times i have seen that the problem is that Power Save Mode is enabled, to disable go to Current inspection profile (lower right corner in Android Studio).