Really? It has the same structure as the link you posted and it seems to spawn parent and child processes just fine. The process forks in the first if statement and catches any failure in the last one and the first internal if executes if it's the child and the second for the parent. Or maybe I'm just super lost?

I don't want to give it all away as Swing is best learned through a bit if struggling (imo) but think about what you're trying to do here. Based on what you've said, it looks like you need to:
a. see if the length of the text field's contents is greater than 0
b. try to convert the contents of the text field to an integer

A common way of achieving the error message behavior is to dynamically add a JComponent subclass to a JFrame (such as a JLabel), setting the text to some error message, and then forcing the frame to revalidate, causing it to draw any new components you've added. Check out the JTextField and Integer classes in the Java API (linked version 7, not sure which you're using), particularly the Integer.getInteger() and JTextField.getText() methods. Also, the String.length() method ought to help you out for detecting whether or not a field has been populated. Google around for tutorials on dynamically adding JLabels and other components to JFrames, I think there are a couple floating around

@ishkabible: see if you can get in touch with Carol, the one who runs the GSoC program at Google. Or just ask on the mailing list - I'm sure they'd be willing to make an exception since you'll be in college for most of the program duration.

I participated last summer and am in the final runnings to participate this summer. Unfortunately you've missed the Student Application deadline, which was somewhere back around April 8th I believe, but if you'd like to go for it next summer here are a few tips:

1. Do your absolute best to become super comfortable in at least one programming language. The majority of the organizations I that are accepted into GSoC generally run projects coded in C++, Java, and Python (not necessarily in that order), it that's any help. It's Open Source - there are a lot of really great developers out there and there will probably be a lot of techniques both at the code and structure level that you've never seen before; a solid handle on common data structures is also going to be super helpful. Don't be cocky about your knowledge though, it helps to join a project in a humble state of mind and just look to help, not revamp - you make friends a lot faster that way. jon.kiparsky makes a great point in this thread, and I'd highly suggest reading what he says.

2. This depends on the organization, but most of them like their students to either already be involved in the community or to at least submit patches to fix problems in their issue trackers. If you ask about any student-friendly tasks on their mailing lists, usually the core developers will be more than happy to help you find something you can manage. Last year I submitted one patch to fix a small problem and this year I've submitted two and may even need a third - it generally depends on the competition.

3. The project proposal is (obviously) pretty much the biggest component of the GSoC program - start on it and submit it EARLY! Like, the first day you can submit proposals kind of early. But don't just hack it together from some comments on an issue in their tracker - hop on IRC or their mailing list and chat with the community to see what's needed. Open Source is 100% dependent on its community and usually there are people around who will help you out. Usually the organizations will have a "GSoC Project Ideas" page for beginners, they don't expect everyone to come in with a ton of experience. The reason I say submit it early is because the earlier the mentors and organization admins can get to it, the earlier they can make suggestions and give you feedback, which only improves your proposal and increases the likelihood you'll make it in.

4. If there's one thing you need to do your best to master, it's how to use a decentralized version control system such as Git or Mecurial. There are lots of resources online (I use Pro Git all the time) for learning how to use these systems and they make your life way easier. You'll be forced to use one regardless of the organization/project you choose, and I can speak from experience (eg, last summer) that coming in without knowing much about it is rough. They're also just pretty useful for your own projects and you'll see dvcs' again in your career.

5. This may seem obvious, but it's worth mentioning: make sure you apply to an organization you like and come up with a proposal that you're legitimately interested in; it'll be a long summer if you don't.

I have to apologize for the rather lengthy post, but hopefully you'll find some of this advice helpful. It can be pretty nerve-wracking to start contributing to an open source project for the first time. but don't be afraid to ask for help. Good luck

^ I'd definitely heck out BitBucket, I just set up an account myself and if you have a .edu email from college or something then you get a free unlimited account, which is incredible. It looks extremely powerful and even has integrated wiki pages that you can set up for your projects along with issue tracking. It's also got a ton of documentation for usage

...can you tell I'm excited?