I've watched a few online presentations that briefly mentioned self-contained applications in Java 9, but I have a question that I would like cleared up.
With the new module system, you're now allowed to only include the minimum amount of code required to run your application. However, does the system that wishes to run the application still require the JRE, or is that something that can be included in the base module within the program?
I suspect it's the latter, as the page (here) to download the newest version of Java still shows version 8_151.
TL;DR - Using Java 9, is it possible to create a self-contained executable that can be executed on a system without the JRE/Java installed?
Yes, this is possible with jlink (JEP 282), but all of your code and your dependencies need to be modular JARs (i.e. ones with module-info.class). It works like this:
jlink
--module-path $JAVA_HOME/jmods:mods
--add-modules your.app
--launcher launch-app=your.app
--output your-app-image
In detail:
--module-path lists the folders that contain modules - this needs to include the platform modules shipped with the JDK you want to use (in $JAVA_HOME/jmods) and your application modules (mods)--add-modules names the module(s) that you want your runtime image to contain - all of its (their) transitive dependencies are included--launcher is optional, but very handy; it creates an OS-specific launcher (e.g. a .bat on Windows) with the given name (launch-app) that launches the specified module (your.app; in this case assuming the main class is defined for it)--output specifies where to create the runtime image