Trying to Update JLabel inside a ActionEvent

Question

I read that you can't update the UI while inside an ActionEvent ... I have a very small program and think that creating a new thread would be over the top for this. Can anyone offer any other ideas ? Here is the action event listener.
public void actionPerformed(ActionEvent ae)
     String command = ae.getActionCommand();
     if(command.equals("createFile"))
          completedL.setText("Generating spread sheet, please wait..... ");
          completedL.repaint();
          System.out.println(ae.getActionCommand());
          storeNumber=storeNumberF.getText();
          cardNumber= cardQtyF.getText();
          found = info.find(storeNumber);
          if(found != null)
               System.out.println("Found " + found.getStoreNumber());
               storeNumber =found.getStoreNumber();
               System.out.println("Last card # is " + found.getCardNumber());
               cardValue =found.getCardNumber();
          else
               System.out.println("can't find " + storeNumber);//put system dialog box here !!
          h = Integer.parseInt(storeNumber);
          x = Integer.parseInt(cardNumber);
          System.out.println("Store # : " + h +" Card Qty " + x);
          try
               makeSheet(h,x,cardValue);
          catch(IOException ioe)
               System.out.println(ioe);
}Been looking at this for a few days and have tried various things. I'd be willing to give threads a shot, but to me it seems like there should be another way.
-Ben

Answer 1

makesheet() is the one that takes a while. I made the following adjustments and it didn't update the label until the end just like before :
public void actionPerformed(ActionEvent ae)
     String command = ae.getActionCommand();
     if(command.equals("createFile"))
          completedL.setText("Generating spread sheet, please wait..... ");
          completedL.repaint();
          System.out.println(ae.getActionCommand());
          storeNumber=storeNumberF.getText();
          cardNumber= cardQtyF.getText();
          found = info.find(storeNumber);
          if(found != null)
               System.out.println("Found " + found.getStoreNumber());
               storeNumber =found.getStoreNumber();
               System.out.println("Last card # is " + found.getCardNumber());
               cardValue =found.getCardNumber();
          else
               System.out.println("can't find " + storeNumber);//put system dialog box here !!
          h = Integer.parseInt(storeNumber);
          x = Integer.parseInt(cardNumber);
          System.out.println("Store # : " + h +" Card Qty " + x);
     //     try
               Runnable makeSheetRun = new Runnable()
                    public void run()
                         try
                              makeSheet(h,x,cardValue);
                         catch(IOException ioe)
                              System.out.println(ioe);
               SwingUtilities.invokeLater(makeSheetRun);
     //     catch(IOException ioe)
     //          System.out.println(ioe);
}