Currently, j2as3(http://code.google.com/p/j2as3) allows developers to write code in Java and have it converted to Actionscript3. But there's no code assist in Eclipse/Netbeans for Actionscript-facing java code. These libraries are a collection of empty documented classes to provide code assistance in Eclipse for the Actionscript 3 API. Away3DLite and other APIs are in the works as well.