brox wrote:No lightweight java IDEs. Forget it. Raspberry Pi is beautiful platform to run java compiled classes, and believe me, performance is enough for very serious applications. But developing in java on Raspberry Pi is waste of time. No one does this. So get a PC with Windows/Mac/Linux, buy Intellij IDEA and have your programming paradise. You will never return back to developing java in Notepad or Eclipse or whatever.
This is such an unhelpful reply that it deserves an informed response.
The OP very specifically stated that he needed something that will run on the Pi as that's the only computer his nephew will have available to himself. So, a second computer isn't an option and besides, his nephew is 10, so cross-compiling and having to move files around would be an unnecessary complication when just starting out. A ten year-old is going to be starting with developing programs on the level of Hello World for a while, so editing in Leafpad or other text editor and compiling and executing from a command line, or using Geany as a very minimal IDE will work just fine (it highlights keywords, which can be helpful).
In addition to using a nuclear weapon where a fly swatter is much more appropriate, starting a young child in a full-fledged IDE is counter to the whole idea behind the Pi - learning how computing technology really works. They should start out on the command line so that they will understand what the OS is doing before they even start learning to program. Once they're familiar with the command line and navigating around the filesystem hierarchy, compiling simple programs there will be a very simple step up in complexity. They should learn what the various compiler flags and arguments are for and practice using them, as well as what environment variables are and how they are used.
Only after they've gotten to the point where they understand the fundamentals should they be introduced to an IDE, when it's more a matter of convenience and speed than education. Since the OP is conversant in Java, they will be able to provide all of the help necessary to follow this progression. The adults here apparently have forgotten what it's like to be a 10 year-old - they're quite capable of intellectually digesting pretty much anything as long as it's cut up into bite-sized pieces. They might be able to point-and-click their way through an IDE, but they will be doing it monkey-see, monkey-do, without understanding what's really going on. I'm speaking as a science and math teacher at this age level who has been a software engineer for over 40 years.
The nephew will also appreciate the power of an IDE much more after they've spent a sufficient amount of time working at the command line level. They may even find that they prefer working in a text-only environment, but they won't know if all they are shown is an IDE. If they do have trouble with the command line because of a natural affinity for more visual manipulation over symbolic operations, then an IDE can be used for some immediate gratification, but they should be exposed to both approaches to ensure they really understand what's happening.
The best things in life aren't things ... but, a Pi comes pretty darned close!
"Education is not the filling of a pail, but the lighting of a fire." -- W.B. Yeats
In theory, theory & practice are the same - in practice, they aren't!!!