i've never worked with dialog boxes in java, just command line or from a file. But i assume that the spaces in a dialog box are assigned to variables, so when you enter a name, it is stored in a variable, or maybe a variable array. though I may be very wrong.
Once you find out how to get the input, writing to a file is pretty easy.
First you will need to use the FileWriter class. Depending on what version of java you are using, this sight is very helpful
http://java.sun.com/j2se/1.5.0/docs/api/
anyway...
for writing to a file, do something like this.
PrintWriter fout = new PrintWriter(new FileWriter("filename"));
fout.println("Whatever you want " + your_data + " you get the idea");
fout.close()
DONT FORGET THAT LAST LINE! If you don't close the file, it will be empty when you try to open it, and it is frustrating to figure out what's wrong, until you finally realize you never close it. I hope that helps some
Do you know what class you are using for the dialog box?? is it JOptionPane? or something different?