Is NetBeans configured only for the Oracle's JDK, or are there any other SDKs or compilers that NetBeans can work with?
In principle, the NetBeans IDE should function with any compliant Java runtime meeting the Java SE 1.4, 5 or 6 platform specification (depending on the version of NetBeans). Since most Java implementations are based on code licensed from Oracle (Sun), most of the implementation tends to be the same anyway.
Building projects is done by running Apache Ant. By default, Ant looks for tools such asjavacor in the same Java runtime as Ant itself runs inside, using com.sun.** classes, so you will need to run the IDE in a full JDK, not a JRE. It is however possible to build and run applications using other tools and VMs: just for example, you can use IBM's Jikes to compile classes, and you can even build 1.1-compliant applications if you like: FaqJdk11
The integrated source debugger does need to have access to JDI classes in the IDE's virtual machine. The Sun JDK and all licensed JDK ports (1.4+) should include these classes.
See more details about Java SE version required for your version of NetBeans in the Release Notes document.
Applies to: NetBeans 4.x, 5.x, 6.x