In the past I wrote two posts about Java sripts and their portability using shebang. As far as I can tell everything in these two installments is still valid, only now, in Java 21, thanks to JEP-445 things can be even simpler. In this post I’ll try to describe fist the changes introduced by this JEP, then go deeper on how they relate to the “scripts in Java”. I’m going to cover how you can simplify your main method, get rid of the class surrounding it, and even show you when it won’t work.
As I wrote in my previous post I had issues running code using JEP 443 using tools like Maven, Gradle or IntelliJ IDEA. Thanks to the one and only Tagir Valeev the solution is quite simple. Upgrade to JDK 21.0.1. And that’s it ;-) No need to touch anything else. If you fancy more explanation, please follow on this Twitter thread. And we shall all remember that upgrading is a good thing, because we’re not going to stay on Java 8 forever, right?
Update The issue has been solved, please go to the post with solution. Note: I’m leaving the original post below in case someone bumps to a similar issue in the future. Sometimes it’s easier to search using the problem ;-) While preparing my Deep Dive talk on Java 21 for friendly Java User Groups, I’ve noticed a curious case of JEP 443: Unnamed Patterns and Variables (Preview). I’ve managed to create a reproducer, so I’d like to share the findings here.
Java™ 21 is real now. And so are virtual threads. Everyone got excited about them, yet you prefer to keep your Java 8 job forever, and you already have a nice plan to “accidentally” derail the migration to 21 by using virtual threads in a very, very unfortunate way. What a pity… So you decided to come for this talk to look for some inspiration ;-) Okay, please join us to learn how NOT to use virtual threads, and see the potential performance pitfalls of using them the wrong way.
Hey, there are two major Java versions released every year! We don’t have to wait 3 years or so for new features anymore. Isn’t that cool? 😉 Java was supposed “to be slow”. However, Java turns out to evolve so fast, that next releases aren’t just version bumps, but might significantly change the rules of the game. That’s a good reason to check out what’s new in Java. To name a few changes:
Let me start this entry with a dad joke. An electron rides a motorcycle. Suddenly, a police officer stops the electron and says: ‘I had to stop you, because you were speeding, driving exactly 178 and half kilometres per hour.’ ‘Well, THANK YOU VERY MUCH, officer!’ the electron says, ‘Now I have absolutely no idea where I am!!!’ Some dad jokes are terrible, and don’t worry if you don’t get this one.