Multi-release JARs allow you to create a single JAR that contains bytecode for several Java versions with jar –version 9 (or 10, or…). Presented with a multi-release JAR, JVMs version 9 and later will load the code that was included for their version.
So, Java 9 came out last year… What now? Where to get started? If that’s what you’re asking yourself, then you’ve come to the right place! This Java 9 tutorial is a condensation of all you need to know to find your way around the new release, to get you ready to explore it in more depth.
2017 draws to a close and 2018 is knocking. My annual review and preview went to my newsletter, so subscribe or head over to Medium to read them.
Want to build with Maven on Java 9? Here’s which versions to pick, how to use the compiler executable, toolchains, and mavenrc to run Maven on Java 9, and how to use mvn/jvm.config and profiles to configure your build for Java 8 and 9.
Java 10 introduces ‘var’ which lets the compiler infer local variable types. Here’s how it works, why it exists, and how it impacts readability.
Using annotations from JSR-305 (@Nonnull, @Nullable, etc.) with others from the javax.annotation package (@Generated, @PostConstruct) on Java 9 causes a split package. Here’s the fix.
Learn all the module system basics in this tutorial: how to declare modules with module-info.java, compile, package, and launch them and what role the module path and readability graph play.
Java 9 introduces unified logging, a central mechanism configurable with -Xlog to observe class loading, threading, the garbage collector, the module system, etc.
Get your code running on the Java 9 Module System with the command line options –add-exports, –add-opens, –add-modules, –add-reads, and –patch-module.
Time to put your Java 9 knowledge into practice and plan your applications migration. Here’s how to get an overview of what needs to be done.