Some people here listed some of their favourite Java IDE.

IMO, I've used JBuilder and was happy with it, and never bothered to check
out others. It'll be helpful when posters suggest an IDE, they can also point
out the unique features. I'll do that for JBuilder.

The most valuable tool that speeds up my development time is the true, real
time, code in sight. i.e. the method signatures pop up as I type. It is also
100% seamless, as I do not need to manage the code in sight separately as in
Forte, just include any jars in your classpath, and it works.

The real time compilation/error checking is also useful, I know instantly
when a line of code is wrong by a red icon that shows up on the left non
intrusively. This prevent the situation of compiling the first time after 30
mins
of coding, and getting 30 error messages of minor programming errors.

I've also installed JREfactory(name??) plugin downloadable from sourceforge.
It allows painless refactoring, such as renaming a classname, moving to
another package, and it will automatically modify all references throughout
project. It will also beautify source code according to your preference (C style
or shell script style).

On JBuilder 6 Enterprise(what I'm using at work), seamless code in sight
will even extends to JSP pages. Making developing spagetti JSP files an ease
(not good practice, but does the job quick). What amazes me is that it can even
recognizes TEI, and make the new bean available to code in sight.

Finally, there are other small features such as automatically generating
getters and setters, XML view, auto generate javadoc, etc.

However, on JBuilder ver >= 7, the program seems to be abit sluggish on my
Duron 600Mhz PC.