New to Java

Hi. I want to set up my environment for developing java programs. I have done some java programming in the past and I ran into problems. Now I'm trying it again and I would greatly appreciate your advice.

There seem to be a lot of different applications and class packages from Sun and Apache and others and I'm having trouble figuring out what is available and what of that I should install and I've gotten very frustrated in the past because I thought I had to write a bunch of utility classes that turned out have already been written.

So my question is: What do I need to make a reasonably complete java development environment? Or is this a naive question? Thanks. Eli