When the user types the text into the field and presses create. The JFrame title changes to updated user title. The JFrame title variable is in --Window.java-- and the user input is in --NewFileBox.java--. I don't know how you would implement the changes from separate files.
Try
JOptionPane.showOptionDialog(null, nfb.inputs, "Create", JOptionPane.DEFAULT_OPTION, JOptionPane.INFORMATION_MESSAGE, null, new Object[]{}, null);
Arg:
*"Create" --> User define title of Dialog Box