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

Thanks for the help. I started with trying to use the first response, but I couldn't get the bar to run concurrently, and it ran when the program finished. I'm sure it would work, but I wasn't able to figure it out. Using trashgod's response and some other examples, I was able to get it to work using SwingWorker. Unfortunately, I don't totally understand how it works, but I'll take it for now.

The gui and method to run the calculations are called in another class first:

iterations = (int) (MPay - (M1Start + M2Start));
        twoLoan myLoan = new twoLoan();
        myLoan.createGui(iterations);
        myLoan.runCalcs(MPay, Step, L1, L2, C1, C2, IM1, IM2, M1Start, M2Start);

Then it runs as follows:

public class twoLoan extends JFrame {

    JFrame progressFrame;
    JProgressBar progressBar;
    JLabel label = new JLabel("Calculating...");;
    Container pane;

    double amountSaved = 0;
    int i = 0;
    int iterations;

    public void createGui(int iterations) {
           //Create all components
          progressFrame = new JFrame("Calculation Progress");
          progressFrame.setSize(300, 100);
          pane = progressFrame.getContentPane();
          pane.setLayout(null);
          label = new JLabel("Calculating...");
          label.setBounds(115, 35, 200, 25);
          progressBar = new JProgressBar(0, iterations);
          progressBar.setBounds(10, 10, 280, 20);
          progressBar.setStringPainted(true);
          //Add components to pane
          pane.add(progressBar);
          pane.add(label);
          //Make frame visible
          progressFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          progressFrame.setResizable(false); //No resize
          progressFrame.setLocationRelativeTo(null);
          progressFrame.setVisible(true);
    }

    public void runCalcs (double MP, double StepAmt, double L1, double L2,
            double C1, double C2, double IM1, double IM2, double M1Start, double M2Start) {

        progressBar.setIndeterminate(false);
        TwoWorker task = new TwoWorker(MP, StepAmt, L1, L2, C1, C2, IM1, IM2, M1Start, M2Start);
        task.addPropertyChangeListener(new PropertyChangeListener() {

            @Override
            public void propertyChange(PropertyChangeEvent e) {
                if ("progress".equals(e.getPropertyName())) {
                    progressBar.setIndeterminate(false);
                    progressBar.setValue((Integer) e.getNewValue());
                }
            }
        });
        task.execute();
    } //end method runCalcs

    public class TwoWorker extends SwingWorker {

        private final double MP, StepAmt,L1, L2,
            C1, C2, IM1, IM2, M1Start, M2Start;

        public TwoWorker(double MPa, double StepAmta, double L1a, double L2a,
            double C1a, double C2a, double IM1a, double IM2a, double M1Starta, double M2Starta) {

            MP = MPa;
            StepAmt = StepAmta;
            L1 = L1a;
            L2 = L2a;
            C1 = C1a;
            C2 = C2a;
            IM1 = IM1a;
            IM2 = IM2a;
            M1Start = M1Starta;
            M2Start = M2Starta;
           }
        @Override
        protected Double doInBackground() {

            double M1 = M1Start;
            double M2 = M2Start;

        // Set MinLoop as maximum to start
        // Loan 1
        double N1 = (Math.log10(1 - IM1 * L1 / M1) * -1)/Math.log10(1 + IM1);
    double M1Sum = M1 * N1;
    // Loan 2
    double N2 = (Math.log10(1 - IM2 * L2 / M2) * -1)/Math.log10(1 + IM2);
    double M2Sum = M2 * N2;
    double minLoop = M1Sum + M2Sum;
    double MTotal = 0;

        // Define variables for mins
    double MP1 = 0;
    double MP2 = 0;
    double NP1 = 0;
    double NP2 = 0;
    double MP1Sum = 0;
    double MP2Sum = 0;

        while ( M1 <= MP - M2Start && M2 >= M2Start ) {
            N1 = (Math.log10(1 - IM1 * L1 / M1) * -1)/Math.log10(1 + IM1);
            M1Sum = N1 * M1;
            N2 = (Math.log10(1 - IM2 * L2 / M2) * -1)/Math.log10(1 + IM2);
            M2Sum = N2 * M2;
            MTotal = M1Sum + M2Sum;
            if (MTotal < minLoop) {
                minLoop = MTotal;
                MP1 = M1;
                MP2 = M2;
                NP1 = N1;
                NP2 = N2;
                MP1Sum = M1Sum;
                MP2Sum = M2Sum;
            } // end if
                        i++;
                        progressBar.setValue(i);
                    M1 = M1 + StepAmt;
            M2 = MP - M1;
            // Reset monthly sums
            M1Sum = 0;
            M2Sum = 0;
        } // end while

        System.out.printf("MP1 = %.2f\n", MP1);
        System.out.printf("MP2 = %.2f\n", MP2);
        System.out.printf("NP1 = %.2f\n", NP1);
        System.out.printf("NP2 = %.2f\n", NP2);
        System.out.printf("MP1Sum = %.2f\n", MP1Sum);
        System.out.printf("MP2Sum = %.2f\n", MP2Sum);
                System.out.printf("MTotal = %.2f\n", minLoop);
                System.out.printf("i = %d\n",i);
                System.out.printf("M1Start = %.2f\n", M1Start);
        System.out.printf("M2Start = %.2f\n", M2Start);
                System.out.printf("MP= %.2f\n",MP);

    // if there's a value for current payments, calculate amount saved
    if( C1 > 0 ) {
        double CN1 = (Math.log10(1 - IM1 * L1 / C1) * -1)/Math.log10(1 + IM1);
        double CT1 = CN1 * C1;

        double CN2 = (Math.log10(1 - IM2 * L2 / C2) * -1)/Math.log10(1 + IM2);
        double CT2 = CN2 * C2;

        double CTotal = CT1 + CT2;
        amountSaved = CTotal - minLoop;
        } // end if

        return null;

    } // end doInBackGround

        @Override
        protected void done() {
            label.setBounds(133, 35, 200, 25);
            label.setText("Done!");
        }
    } // end TwoWorker


    public double savedReturn() {
        return amountSaved;
    }

} // end class twoLoans