NetBeans 9 runtime platforms are only JDK8 and JDK9. Until JDK9 is GA it is recommended to run NB9 on top of JDK8 which is more stable. JDK9 can be used as Projects Java Platform even NetBeans itself is running on top of JDK8.

Java Platform Module System Support

Java Application project extensions

NetBeans 9 supports JPMS (Jigsaw) to full extent. Modulepath was added as a crucial paradigm to NetBeans in addition to Classpath.

Standard NetBeans Java SE Project (Ant) can be a single JDK9 module simply by adding module-info.java into default package.

module-info.java supports code completion,...

Full Edit - Compile - Debug and Profile cycle is supported. Java SE projects with JDK9 module can define dependencies on themselves using Project Libraries customizer dialog and by defining appropriate exports and requires in their module-info.java files.

This picture shows dependency of 1 project on 2 other projects. The mix of projects with module-info.java or without it is allowed. Modulepath and Classpath are supported.

It is possible to show module dependencies graph for each module-info.java.

Java SE Project allows to develop and store JUnit tests:

1. inside same module. In this case no changes to develop and execute tests are needed in main module-info.java
2. in its own JUnit JDK9 module (own module-info.java). In this case main module-info.java exports the tested packages and tests module-info. java requires application module and JUnit...

The picture below shows the structure of JavaSE projects with JUnit tests in same module and with own module:

Java Modular Application Project type

New project called Java Modular project was added. This allows to develop several JDK9 modules in one NetBeans project (Ant based). Advantage of this project over several Java SE project each containing 1 module is that dependencies are simply managed by declaring appropriate exports and requires in module-info.java files and all modules in the project are being compiled at once.