
IntelliJ
IntelliJ IDEA is a commercial Java IDE by JetBrains, often referred simply as IntelliJ.
The latest version of IntelliJ (11.1) includes a number of advanced features such UML-like class diagrams, visual Hibernate modeling, Spring 3.0 and Play Framework support, Dependency and Data Flow Analysis, Apache Maven support, Intelligent Coding Assistance and On-the-fly Code Analysis. A complete list can be found at their features page.
Jetbrains provides a fully functional 30-day trial version of the commercial edition for various platforms. Also available is an open source Community Edition. Check the differences between commercial and community versions here.
You can extend IntelliJ default features by installing plugins. Right now their Plugin Repository lists more than 500 plugins, both freeware and commercial.
Here you can find more information about how Using IntelliJ with Liferay