Write to a specific line in a file

[phantom06]

I have this file:
Crazy love hollywood edition,Crazy love,04:26,Hold on,04:01
Recovery,Love the way you lie,04:23,Cinderalla Man,04:36
Speak now,Mine,03:55,Speak now,04:03

How do i write to the end of each line?
For example:
In this line, i want to add hello, 05:34
Recovery,Love the way you lie,04:23,Cinderalla Man,04:36

Thus, it will look like this:
Recovery,Love the way you lie,04:23,Cinderalla Man,04:36,hello, 05:34

I need to use a gui to do this
Is there any way? The comma are used as delimiters.
Thank you

[Fubarable]

First figure out how do to this without a GUI, using Java I/O, then later use that same code as the "model" for your GUI. The Java tutorials will show you how to do the IO, and if you haven't studied them, I recommend that you give them a look.