Um... No.

Do they know at what rate it changes color if I keep it several days ?

Just as much as Google News is.

what kind of behavior would demonstrate that LLMs did have understanding?

An LLM would need to act like an understander -- the essence of the Turing Test. Exactly what that means is a complex question. And it's a necessary but not sufficient condition. But we can easily provide counterexamples where the LLM is clearly not an understander. Like this from the paper:

When prompted with the CoT prefix, the modern LLM Gemini responded: âoeThe United States was established in 1776. 1776 is divisible by 4, but itâ(TM)s not a century year, so itâ(TM)s a leap year. Therefore, the day the US was established was in a normal year.â This response exemplifies a concerning pattern: the model correctly recites the leap year rule and articulates intermediate reasoning steps, yet produces a logically inconsistent conclusion (i.e., asserting 1776 is both a leap year and a normal year).

Books: The Bourne trilogy, which, contrary to the movies, were very entertaining.

Like this ?

Everyone is using OpenJDK these days, nobody in their right mind would pay for their licensing.

The planet may disagree though.

A plumber can make art while plumbing. A truck driver can make art while driving. Yet that is not the first purpose of their jobs. Hence, in general, a truck driver is not an artist. Of course, nothing prevents a truck driver from being an artist.

Same for engineering (software here). Our job is to build / maintain systems. Not to create art. Now, we can create art in the process, of course, just like everyone else. But no, engineering is not art by any stretch of the imagination.

Art: the expression or application of human creative skill and imagination, typically in a visual form such as painting or sculpture, producing works to be appreciated primarily for their beauty or emotional power.

Engineering is an activity that has a practical goal: Build a plane, make a website, make this piece of code scale. Not activities primarily appreciated for their beauty or emotional power.

If your program will be up for days (think a server, a browser, etc...), the startup time can easily become negligible.

Well, each thread uses its own buffer, so there is no issue, is there ? They can then switch buffers when they feel the need to.

Engineering is inherently a creative job, so is researcher, and many others. That does not make it art.

Java is slow to start, because the JVM is a beast that takes its sweet time to get up to speed. After this hit, the type of code you are talking about will be about 5 to 10 % slower, which might be acceptable or not depending of your requirements and the value you put in all that Java provides and C does not.

The reason so few games are written in Java is that the GUI layer is not efficient to optimize your UI down to your graphic chipset *and* the fact that a full GC will stop the world fr a split second and you have no control over it. So, a game needs fluid interface which the GC doesn't allow and lightning fast graphics performance which java is not equipped for. The general CPU performance of Java is not at all an issue there.