z2-Environment

h2. Java 9 Support (#1991)

h2. Supporting the Java 9 Language

We integrate ECJ version 4.7.2 from the download link below. Java 9 is fully supported since 4.7.1a ("New and Noteworthy 4.7.1a":https://www.eclipse.org/eclipse/news/4.7.1a/)

* "JDT Core 4.7.2":http://download.eclipse.org/eclipse/downloads/drops4/R-4.7.2-201711300510/#JDTCORE

* "New and Noteworthy 4.7.1a":https://www.eclipse.org/eclipse/news/4.7.1a/

* "JDT Core Git":https://git.eclipse.org/c/gerrit/jdt/eclipse.jdt.core.git/

* "JDT Core main":https://www.eclipse.org/jdt/core/dev.php

* "Oxygen help":http://help.eclipse.org/oxygen/index.jsp

We support a new LangLevel.JAVA9 and derive all compiler settings accordingly.

Unfortunately using Java 9 actually requires an updated Jetty version ([[Jetty9_4_support]]).

h2. Supporting the Module System

The Java 9 module system provides for module level package exports and cross-module dependencies. As such it does not contradict the class loading delegation model but rather adds a dimension to it: Layers

Supporting the Java 9 module system (project jigsaw) from Z2 means:

* A Java Component consists now of up to three layers, one for API, one for impl, one for test.

* All other module declaration business is out of scope for the Z2 runtime but rather purely development oriented business.

References

* "State of the module system (easy and comprehensive read)":http://openjdk.java.net/projects/jigsaw/spec/sotms/

* "Project Jigsaw":http://openjdk.java.net/projects/jigsaw/

* "Jigsaw delivered":https://mreinhold.org/blog/jigsaw-complete