Note We recommend you keep 2.1.1 and 2.2 Preview 7 installed side by side; they already use separate settings and cache directories. More information on how to install multiple versions simultaneously.
Due to a bug, you can only patch from Android Studio 2.2 Preview 2, 3, 4, 5 and 6. All other versions will need to download a complete install of the IDE.
With Android Studio 2.2, you may have noticed the larger download sizes than previous versions of Android Studio; this is because we now bundle a build of OpenJDK with the IDE to address various font rendering and stability issues.