Advanced Web Machinery

I sadly didn't write everything down, or didn't keep references to the GitHub issues, but here's a few of the things that i ran into. Here's a list of the things that were available in JDK 8 and no longer are: https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features… When you stumble upon something like that, at best you can import a Maven dependency with a version that has what you need, at worst you need to rewrite the code to use another library or set of libraries. If you have any low level logic like custom class loaders written against older JDK versions (think before 8), then they'll be forwards compatible until 8 for the most part, but will break afterwards. Coincidentally, reading code that deals with low level logic is also not easy to do, especially if it's not commented well. If you rely upon reflection, or use advanced language features (like the JasperReports framework for generating PDFs, which also has a build step for building the reports), in some cases things might compile but not work at runtime due to class mismatches. Many frameworks need new major versions to support newer releases than JDK 8, for example Spring Boot 1.5 needs to be upgraded, so you're also dealing with all the changes that are encapsulated by your dependencies. In another project that i also migrated, needed to rewrite a lot of web initialization code for Spring Boot 2.X. Not only that, but with those framework changes,…

You might find those useful: https://www.marcobehler.com/guides/a-guide-to-java-versions-and-featur… https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features… And this more like a reference: https://javaalmanac.io/

Plenty, Up to Java 21, https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features… Remaining ones until Java 24, released last week, https://www.infoworld.com/article/2335077/jdk-22-the-new-features-in-j… https://www.infoworld.com/article/2336682/jdk-23-the-new-features-in-j… https://www.infoworld.com/article/3491404/jdk-24-the-new-features-in-j… Additionally, commercial AOT compilers have taken a big hit, as two great options are now freely available, https://www.graalvm.org (Basically LLVM, but in Java) https://eclipse.dev/openj9/docs/aot With them there is also the rise of AOT friendly frameworks like Quarkus and Micronaut.

https://reflectoring.io/java-release-notes/ https://advancedweb.hu/new-language-features-since-java-8-to-18/

Also, it bears mentioning that there has been a lot of momentum around new language feature in the past 5 or so years. Good overview here: https://advancedweb.hu/new-language-features-since-java-8-to-17/ And many other changes in the pipeline too..

https://advancedweb.hu/new-language-features-since-java-8-to-17/#local… > Available since: JDK 11 (Without lambda support in JDK 10) TOC is missed up, there is no java-10 at all.

Introduced in Java 10: https://advancedweb.hu/new-language-features-since-java-8-to-17/#local…

https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features… Only missing stuff from 17, but that's a short list.

Here's another similar summary, but with code examples and categories. https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features…

IIRC the JVM optimizes very aggressively based on runtime profile, and just adds traps to the optimized-out paths to collect new runtime profile. Imagine code like this, where at runtime foo is always null if (foo != null) { foo.bar(); foo.baz(); } if foo is always null the compiler will just remove all of the statements inside and places a trap there. If foo happens to be non-null (say, due to external environment changes) then the it hits the trap and the whole method is deoptimized and goes through the profiler again. The optimizations in the JVM are quite fascinating - https://advancedweb.hu/profile-based-optimization-techniques-in-the-jv… I imagine javascript engines employ similar techniques