Progress Bar Java

I am using JProgressBar to show progress. But, How to show the progressBar as loading from 0 to 100? I got the code from internet and its working except the progressBar is not loading.

code

progressFrame = new JFrame(); // frame to display progress bar
progressBar = new JProgressBar(0,100);
progressBar.setValue(0);
progressBar.setStringPainted(true);
progressFrame.add(progressBar);

new SwingWorker<Void,Void>()
    {
        protected Void doInBackground() throws SQLException, ClassNotFoundException
        {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            progressBar.setValue(0);
            frame.setEnabled(false); // frame = main frame

            //tableclass creates a JTable with data from database
            tableclass = new TheDatabaseTable(deptName);//it takes time to create
            progressBar.setValue(50);
            frame.getContentPane().removeAll();
            frame.setContentPane(tableclass);

            frame.validate();
            frame.repaint();

            progressBar.setValue(100);
            //progressFrame.dispose();
            return null;
        }; 
        protected void done()
        {
            //progressFrame.setVisible(false);
            frame.setVisible(true);
            progressFrame.dispose();
            frame.setEnabled(true);
        }

    }.execute();

I would appreciate if anyone edit the above code to work. Thank you.

Gotta love code from the internet...oh...

The code you have violates the singe thread rules of Swing and thus, is a bad example.

You have a number of options with SwingWorker. You could publish the progress and use the process method to update the progress bar or you could use a PropertyChangeListener and monitor progress change events created by calling the setProgress method of the SwingWorker

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.SwingWorker;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;

public class SwingWorkerProgress {

    public static void main(String[] args) {
        new SwingWorkerProgress();
    }

    public SwingWorkerProgress() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JProgressBar pbProgress;
        private JButton start;

        public TestPane() {

            setBorder(new EmptyBorder(10, 10, 10, 10));
            pbProgress = new JProgressBar();
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.insets = new Insets(4, 4, 4, 4);
            gbc.gridx = 0;
            gbc.gridy = 0;
            add(pbProgress, gbc);

            start = new JButton("Start");
            gbc.gridy++;
            add(start, gbc);

            start.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    start.setEnabled(false);
                    ProgressWorker pw = new ProgressWorker();
                    pw.addPropertyChangeListener(new PropertyChangeListener() {

                        @Override
                        public void propertyChange(PropertyChangeEvent evt) {
                            String name = evt.getPropertyName();
                            if (name.equals("progress")) {
                                int progress = (int) evt.getNewValue();
                                pbProgress.setValue(progress);
                                repaint();
                            } else if (name.equals("state")) {
                                SwingWorker.StateValue state = (SwingWorker.StateValue) evt.getNewValue();
                                switch (state) {
                                    case DONE:
                                        start.setEnabled(true);
                                        break;
                                }
                            }
                        }

                    });
                    pw.execute();
                }
            });

        }
    }

    public class ProgressWorker extends SwingWorker<Object, Object> {

        @Override
        protected Object doInBackground() throws Exception {
            int i = 0;
            int max = 2000;

            while (i < max) {
                i += 10;
                int progress = Math.round(((float)i / (float)max) * 100f);
                setProgress(progress);
                try {
                    Thread.sleep(25);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

            return null;
        }
    }
}

You have to use threads for that. Design a class that implements Runnable interface which will update the values like this.

class ProgressBarUpdator implements java.lang.Runnable {

    /**
     * Progress bar that shows the current status
     */
    private javax.swing.JProgressBar jpb = null;
    /**
     * Progress bar value
     */
    private java.lang.Integer value = null;

    /**
     * Constructor
     * @param jpb The progress bar this has to update
     */
    public ProgressBarUpdator(javax.swing.JProgressBar jpb) {
        this.jpb = jpb;
        jpb.setMaximum(100);
    }

    /**
     * Sets the value to the progress bar
     * @param value Value to set
     */
    public void setValue(java.lang.Integer value) {
        this.value = value;
    }

    /**
     * Action of the thread will be executed here. The value of the progress bar will be set here.
     */
    public void run() {
        do {
            if (value != null) {
                jpb.setValue((int)java.lang.Math.round(java.lang.Math.floor(value.intValue() * 100 / maximum)));
            }
            try {
                java.lang.Thread.sleep(100L);
            } catch (java.lang.InterruptedException ex) {
                ex.printStackTrace();
            }
        } while (value == null || value.intValue() < jpb.getMaximum());
    }
}

and in your frame class use progressBar with the new class like this

ProgressBarUpdator ju = new ProgressBarUpdator(progressBar);
new java.lang.Thread(ju).start();

Whenever you want to change the value just use the statement

ju.setValue([Value to set]);