Question: after I define a kind of file format, it is dificult for hosting providers to
register it for my site? i can ask that after i paid the service? it must be a mime type properly register at ietf.

thanks in advance

Answer: 
Try adding a [KeyListener](http://java.sun.com/javase/6/docs/api/java/awt/Component.html#addKeyListener%28java.awt.event.KeyListener%29) on the JTextField
While there are ways to listen for keypress events, it seems like for the task you want to do you should wait until the enter keystroke and then do what you need to do there referencing the value of the jtextfield. The jtextfield is already reading in the characters the user types, you don't need a custom handler to duplicate that (unless you really want to do it character by character, and include non-text character (i.e. "heg[backspace]llo[enter]" is somehow treated differently than "hello[enter]").