i try all the most popular JavaIDE s like Eclipse, JBuilder,
JDeveloper, and
also one low level basic text editors like Editplus, Notepad. i have
to be
found lots of java  projects for 4 years, and i think the best java
ide is
also the least popular one, and also the newest one :

IntelliJIDEA. http://www.intelij.com

Download and try the fully-functional version of IntelliJ IDEA 3.0.4
for a
30 day trial period.