J++ really isn't used anymore. You should be using J# if anything. And in reality, J# isn't that great imo.
While it is optimized for the Windows platform, the problem is that it can't be used on any other platform!
A couple things about J#:
J# does not compile Java-language source code to Java bytecode (.class files), and does not support Java applet development or the ability to host applets directly in a web browser, although it does provide a wrapper called Microsoft J# Browser Controls for hosting them as ActiveX objects. Finally, Java Native Interface (JNI) and Raw Native Interface (RNI) are substituted with P/Invoke, J# does not support Remote Method Invocation (RMI).
J#'s interface to the .NET framework is solid, but not as seamless as C#. In particular, J# code cannot define new .NET properties, events, value types, or delegates. J# can make use of these language constructs if they are defined in an assembly written in another language, but its inability to define new ones limits J#'s reach and interoperability compared to other .NET languages.
So in my opinion, I would use netbeans. It was created by the guys who wrote the Java specification and currently are running the primary open source JDK. And it has a variety of features that could present itself as useful to yourself. Plus when you write and compile from netbeans you can take that jar or class files and run them on any JVM!
Of course, I don't use either. I use eclipse