GUI to set file, other class to read it, file null error

Question

Perhaps not the most informative subject for this problem. I have a GUI in which a file chooser is used to select a file to be read. Another class reads in this file, and goes on to process it. My main class sets up the GUI and then goes on to process the files in the second class.
I am having trouble, I believe, with timing. The main class sets up the GUI, it runs perfectly, and then I catch a problem (that will evolve into an error), where the file I am supposed to process is null, because I have not had a chance to use the file chooser in the GUI. I haven't had any luck finding a solution online, although if there is one (or another tutorial I missed), please feel free to pass the link(s) along. I am posting the relevant code below.
Thanks,
Danielle
public Main()
     * @param args the command line arguments
    public static void main(String[] args)
         javax.swing.SwingUtilities.invokeLater(new Runnable()
               public void run()
                    System.out.println("About to run create GUI method");
                    MGui app = new MGui();
                    System.out.println("declared a new MGui....");
                    app.createAndShowGUI();
        /**Starting to get file choices and moving them into GPR Handler:
          GprHandler gpr = new GprHandler();
     //~ System.out.println("should be perfect????");
     //  }//end if
    }// end main(String[] args)
}// end class MainThe GUI uses the following code for the file chooser:
private class enterFile2Action implements ActionListener
     public void actionPerformed(ActionEvent evt)
          JFileChooser chooser = new JFileChooser();
          int rVal = chooser.showOpenDialog(enterFile1);
          if(rVal == JFileChooser.APPROVE_OPTION)
               inputFile2 = chooser.getSelectedFile();
               PrintWriter outputStream;
               file2Name = inputFile2.getName();
               enterLabel2.setText(file2Name);
}Finally, the GprHandler class processes the file- reading it and such. The only relevant method, however is below.
   /** taking in files*/
    public boolean readFiles()
         boolean nullFiles = true;
         System.out.println("into method readFiles()");
     if (MGui.get1Name() != null)
          System.out.println("name isn't null");
          file1Name = MGui.get1Name();
          file1 = new File(file1Name);
     if (MGui.get2Name() != null)
          file2Name = MGui.get2Name();
          file2 = new File(file2Name);
          nullFiles = false;
     }//end if
     if (nullFiles)
          System.out.println("one or more files is undeclared");
          return false;
     }//end if
     else
        try{
         file1Reader = new FileReader(file1);
            file2Reader = new FileReader(file2);
     }//end try
        catch (FileNotFoundException e)
         System.out.println("file not found exception");
          return false;
        }     //end catch
     }//end else
     return true;
    }

Answer 1

No, you're quite right. I want the GprHandler to
start when I've got something there for it to start
with. I never thought to call it from the
actionPerformed though. I think I've been listening
to too many lectures on some prof's definition of a
"proper main class".
I think I understand what you're suggesting: I
should simply remove the GprHandler part from my main
class and place it instead in the actionPerformed
methods, once the files are actually named/chosen.
Did I get that right?
Qualified yes. Does GPRHandler implement Runnable? I mean you don't want to do the processing in the swing event thread. So what you should do is in the actionPerformed create the Handler (with the file or whatever other bits it needs) and then start it.
Then it can process merrily along in a seperate thread.