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

SwingWorker is ideal for this. The example below performs a simple iteration in the background, while reporting progress and intermediate results in a window. You can pass whatever parameters you need in a suitable SwingWorker constructor.

import java.awt.EventQueue;
import java.awt.GridLayout;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.text.DecimalFormat;
import java.util.List;
import javax.swing.*;

/** @see http://stackoverflow.com/questions/4637215 */
public class TwoRoot extends JFrame {

    private static final String s = "0.000000000000000";
    private JProgressBar progressBar = new JProgressBar(0, 100);
    private JLabel label = new JLabel(s, JLabel.CENTER);

    public TwoRoot() {
        this.setLayout(new GridLayout(0, 1));
        this.setTitle("√2");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.add(progressBar);
        this.add(label);
        this.setSize(161, 100);
        this.setLocationRelativeTo(null);
        this.setVisible(true);
    }

    public void runCalc() {
        progressBar.setIndeterminate(true);
        TwoWorker task = new TwoWorker();
        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();
    }

    private class TwoWorker extends SwingWorker {

        private static final int N = 5;
        private final DecimalFormat df = new DecimalFormat(s);
        double x = 1;

        @Override
        protected Double doInBackground() throws Exception {
            for (int i = 1; i <= N; i++) {
                x = x - (((x * x - 2) / (2 * x)));
                setProgress(i * (100 / N));
                publish(Double.valueOf(x));
                Thread.sleep(1000); // simulate latency
            }
            return Double.valueOf(x);
        }

        @Override
        protected void process(List chunks) {
            for (double d : chunks) {
                label.setText(df.format(d));
            }
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                TwoRoot t = new TwoRoot();
                t.runCalc();
            }
        });
    }
}