If I had to use Java, IntelliJ would be my choice. http://www.jetbrains.com/idea/Quote from Member51:
Trying to decide between Eclipse and Netbeans to use with TWS Java API.
What are folks using out there?
Quote from spacewiz:
IntelliJ IDEA is a level above both of those, if you have to go with IDE free of charge - I would suggest Eclipse - has much wider adoption, and they've been very good at copying all the nicer features from IntelliJ, although they are still a couple of years behind it..