This is a question that is really hard to answer because the requirement and the preferences of the users are different from each other.
But I will tell you one entry point. Use ECLIPSE as your IDE to develop your Java code. It is an opensource one so you don't need any licence for that. When you are working on your project you will need variety of other tools to do various stuff. Fortunately most of the essential functions are implemented as plugins for eclipse. You can seperately add them to eclipse.
With time, you'll get the experience and you will have enough knowledge to swich to the necessary tools etc