Over the past couple of weeks I've been asked the same question a few times by people just beginning to learn Java. What tool should I use to write my programs in? There are plenty of choices out there from simple text editors to integrated development environments.
I always think the best place to start is to use something in between. I call them programming text editors as they are written with programming in mind (e.g., TextPad, JEdit). They offer helpful features like syntax highlighting and the ability to compile code without the need to use command-line tools in a terminal window. But, they don't overwhelm you with a lot of tools that you're not going to use until you become more experienced.