Can a progress bar be used in a class outside main?

Question

Right now, my main just calls a gui with 10 rows. Based on how many of those rows have text, 1 of 9 classes is called (two rows must have text). The called class performs

Answer 1

I think you premonition is right, you need to adhere to Swing threading rules.

So what to do?

First, I am not sure how your app is designed exactly. You say that you have a main frame with a bunch of rows, and potentially each could potentially call one of 9 classes, and they all look like the one above. It seems that these classes will generate their own JFrame. I guess that this new frame is solely used for the progress bar. I will assume that this is the design and will suggest accordingly.

I suggest that you perform a couple actions in instances of Runnable, and you drop those Runnable instances into SwingUtilities.invokeLater to have them run on the EDT. At the same time, I would take the time to reorganize your code for ease if reading.

1. move the creation of your GUI bits into a method:

public void createComponents () {
      SwingUtilities.invokeLater(new Runnable() {
        public void run() {
          //Create all components
          progressFrame = new JFrame("Calculation Progress");
          progressFrame.setSize(300, 100);
          pane = progressFrame.getContentPane();
          pane.setLayout(null);
          progressFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          progressBar = new JProgressBar(0, iterations);
          //Add components to pane
          pane.add(progressBar);

          //Position controls (X, Y, width, height)
          progressBar.setBounds(10, 10, 280, 20);

          //Make frame visible
          progressFrame.setResizable(false); //No resize
          progressFrame.setVisible(true);
       }
      });

    }

1. Then I would methodize the two GUI actions that you have in your calc:

     private void updateProgressBar(final int i) {
           SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                   progressBar.setValue(i);
                   //no need for the following
                   //progressBar.repaint(); 

                }
           });
    }

    private void killDialog() {
           SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    progressFrame.setVisible(false);
                }
            });
    } 

1. Finally, replace where the code contained in these new methods with calls to the methods.