I believe “Preparing” means that the updater files are being downloaded. The download is done by Windows, and it may take some time (Windows somehow decides how to allocate bandwidth, when to download, …)
‘Preparing’ should not be downloading as I didn’t ask it to. It is the bar that appears above More Information on the right while apparently checking a program. There is no downloading going on according to Process Explorer, just rather a lot of CPU usage.
Open up the Software Updater, and click on the STOP button.
then go to avast’s Settings (in the upper right-hand corner), select Software Updater (on the left),
UNcheck the box to “Automatically download updates if possible”.
Click on the down-arrow to expand the “database reset (troubleshooting)” section, and press the RESET DATABASE NOW button. Accept any prompts it offers, and click OK to close the settings screen.
You should be back at the Software Updater (if not, go there). Hit START, and then RESCAN.
Hopefully, it will no longer be continually “preparing” Java (nor anything else).
*** Nor will it automatically download updates in the background without getting your permission. ***