Yesterday NetBeans switched the Java version: The post NetBeans 8.1 versions are now build using Java 8. The nightly builds are available on the NetBeans site .
If you want to be on the bleeding edge, the integration of the Java 9 branch into these builds is the more important part of the new development version. JDK 9 is available at at java.net . You’ll find information about the upcoming version on the appropriate project site .