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copied!<p>Gotta love code from the internet...oh...</p> <p>The code you have violates the singe thread rules of Swing and thus, is a bad example.</p> <p>You have a number of options with <code>SwingWorker</code>. You could <code>publish</code> the progress and use the <code>process</code> method to update the progress bar or you could use a <code>PropertyChangeListener</code> and monitor progress change events created by calling the <code>setProgress</code> method of the <code>SwingWorker</code></p> <pre><code>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; } } } </code></pre>

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