IntelliJ IDEA Community Edition is the open source version of IntelliJ IDEA, a premier IDE for Java, Groovy and other programming languages.
Fast, reliable - great tool with lots of features and support for myriads of frameworks.
Best Java IDE. Open source version lacks some frameworks support (Grails!) but still better then Eclipse/Netbeans.
Really good refactoring support. Super-fast find in files. Very framework aware (e.g. code completion from model in GSPs)
just a lot better than eclipse.
dont get me wrong, eclipse is FREE and its good, but intellij is just better in nearly all functionalities:
better refactoring, covers views and xml files, generate java stuff out of your view
better import of existing projects from eg maven
all frameworks are detected and configured automatically
no eclipse plugin hell
easy and proper deployment of artifacts to runtime, including hotswap
better startuptime and responsivness
autocompletion for view xml etc out of the box
and MUCH MORE
YOU GUYS ROCK