Updating app's JDK with update4j about update4j HOT 5 CLOSED

You just need to use the --release option when compiling/building your jar to target an older version.

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Well, that's sure some way of making it work, but does it mean, that as long as someone still uses older versions, I can't bump up the class version?

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I'm missing a few points.

Copy the whole JDK to a separate folder

Are you saying you download the new JDK in a separate folder, or copy the existing installation?

Run update4j jar with copied JDK

Assuming update4j will run an update; so at this point we now have 3 JDK installations?

Of course due to new main JAR being compiled with newer JDK, it fails to run it and also fails to delete old libs.

I seem to miss something obvious here. You already have the new JDK but start your main jar in the old JDK, why?

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I copy the existing runtime, that's in folder called image to a new folder called updateImage.

Next I run update4j jar with updateImage runtime. This will update all the required files while not interfering with any files, that an update is run with.

The last part means that I declared launcher in update XML. This will run whole application after update, but with updateImage. At this point, it fails to run the new jar due to unsupported class version.

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Sorry for delay, but I'm not in the capacity at the moment to answer your question. It involves me to deeper understand your architecture, and I'm not ready for it.

As a pointer, you might look into Configuration::deleteOldFiles. I'm not sure this helps you in any way though.

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