I need to update my code style. Reformatting the whole project files one by one takes too much effort with the shortcuts I know.

Opt + Command + L

My Question?

Is there any other way to do it for the whole project?

Use the re-format code shortcut (default: ⌘ + Opt + L (Mac) / Ctrl + Alt + L (PC)) in the Project Files View/Explorer on the desired root folder(s) and then check Include subdirectories.

This is how it works in Android Studio 3.5

Right click in your project or lib -> Reformat Code

See the image below:

Select what you want (clean up code will reformat your code)

Wait until the progress finish.

that's it!

Good coding!