I'd actually just recommend Eclipse. It seems bloated at first, but once you get used to it, you can use it to develop code very very quickly (and thus it's an excellent choice for a quick bit of Java).
Features I like:
Control+1 for error fixing - it knows how to fix most compile errors - just highlight the error in the code (which will be underlined in red) and it will give you a list of suggestions. Control+1 selects the first suggestion, which is almost always correct.
You can use this error fixing feature to write code that uses methods you haven't written yet - the error fixing will create the method on the class/interface you called it on, with the correct parameters/name/visibility etc. Or, if theres a similarly named method with similar parameters, it will suggest you've spelt it wrong when you called it.
The refactoring tools are also supergreat - you can highlight a block of code to extract as a method, and it'll work out what variables need to be passed in, and what it should return (if anything). You can move variables between field and methods. You can change class/interface/variable names, and it will correct them only where it needs to (which beats a search and replace any day).
You really don't need to know many eclipse features to get the benefit of using it - and it'll dramatically speed up your coding. I wish I'd known how to use it at University.
Basically, I'd recommend Eclipse. The time saved coding will make up for having to click "yes" a couple times when you start a project..