Amazingly this sort of works!
The link is
https://play.google.com/store/apps/details?id=com.coobbi.jre
Once installed and runing, you'll need to click the green
+ button to load the MC4D jar file. It can't load
it off the web, but can load from Google Drive. I copied it to the
root level of my Android phone, but if you've never done anything
like that, adding it to your Google Drive may be your best option.
Once it is running, you'll see that it is really clunky and almost
unusable, largely because it is rendered much larger than my
display, and I don't see a way to shrink it. Maybe it will work
better on a tablet, so if anyone has a tablet and wants to try it
and report back, that would be very helpful. You can however
painfully scroll the display around using arrow keys at the bottom.
It won't switch to landscape mode which would help.
You can't drag the puzzle around, or at least I didn't find a way.
You can definitely drag the pointer around, hover over a sticker,
and tap the screen to perform a left-twist. You can left-click in
general by putting the cursor over whatever you want and then
clicking anywhere on the screen to generate the click, so that's one
helpful feature. I haven't found a way to perform a right-click or
control-click, but anyone with the patience to use my crude Android
port will probably be glad for this version which is probably
better, even in its current form. There are probably a lot of things
that could be done to my desktop app to support this runtime
environment, but I'm not likely to do that.
It seems to run in a continuous rendering mode and displays the
frames per second at the top. This heats up my phone and may drain
your battery much faster than otherwise.
Still, it's great to finally have any way to run Swing apps on
Android. I've long felt it should be officially supported, but I
guess Google is worried about security. Of course do be careful with
any jar file you run and make sure you trust the developer and the
platform from which you got it before you run it, just like you
would for a desktop app. It may also work better on a more recent
Android version. Mine is very old.
Thanks to Some Person for reporting this very helpful new resource!
-Melinda