Would you elaborate please?

The compiler will see that your operation does nothing and simply not do it.

What I mean was: do you know this to be the case for JVM 8 later? This is an interesting subject. Was there a study or a paper you can refer me to?

JVM 8 isn't an implementation, it's a specification.

Assuming you mean oracles implementation, it's likely that it is.

https://www.sjoerdlangkemper.nl/2016/05/22/should-passwords-... http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buf... https://man.openbsd.org/explicit_bzero.3

Thank you. I was hoping for a more definitive answer, may be a reference to an explicit test involving memory dump analysis.

I believe he is referring to compiler optimisation which removes wasteful or extraneous operations. I don't write in Java though, so can't comment more than that.