synchronize the jprogress bar

Question

   public class frame11 extends javax.swing.JFrame implements ActionListener,
    PropertyChangeListener {


 public String[] columnNames = { "Path",
                    "File Name",
                    "Size"};
       public  Object[][] data ;
int isJPEG (String s) throws IOException
   { int c=0;//not jpeg

    if ( (s.endsWith(".JPG")) || (s.endsWith(".JPEG"))||(s.endsWith(".jpeg"))||(s.endsWith(".jpg")))
{

                c=1;//is jpeg

}
   return c;
   }

           }


    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt)     {//GEN-FIRST:event_jButton1ActionPerformed

    setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
    JFileChooser fch = new JFileChooser("C:\\");
   jProgressBar1.setValue(0);
    jProgressBar1.setStringPainted(true);
    jTextField1.setText(null);
    jTextField2.setText(null);
    jTextField4.setText(null);
    jLabel7.setText(null);
    data = new Object[15][3]; 
    jTable2.setModel(new DefaultTableModel(data, columnNames));
    fch.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
    int ret = fch.showOpenDialog(null);
    int apr=0;
    if (ret==JFileChooser.APPROVE_OPTION)
    {     apr=1;
        jTextField1.setText(fch.getSelectedFile().toString());
        setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
    }
    else jTextField1.setText("Nothing clicked!!!");
    if (apr==1)   {
    jLabel7.setText("Wait Please, While searching ...");
    task = new Task();
    task.addPropertyChangeListener(this);
    task.execute();
    EventQueue.invokeLater(new Runnable() { // Added

            @Override
            public void run() {
                File f = fch.getSelectedFile();
        String s= f.getAbsolutePath();
        int cnt;
        int st=0;
        Path myfile = Paths.get(s);
        if(f.isDirectory()&& Files.isReadable(myfile)){
        try {
        st=st+CheckFiles(f);
        cnt=count(f);
        String ss=Integer.toString(cnt);
        jTextField2.setText(ss);
        jTextField4.setText(Integer.toString(st)); 
        } catch (IOException ex) {
        Logger.getLogger(frame1.class.getName()).log(Level.SEVERE, null, ex);
        }
        }
       jLabel7.setText("Scanning Finished. Thanks for waiting ");
    }

            });

    }

}//GEN-LAST:event_jButton1ActionPerformed
private Task task; 
@Override
public void propertyChange(PropertyChangeEvent evt) {
    if ("progress".equals(evt.getPropertyName())) {
        int progress = (Integer) evt.getNewValue();
        jProgressBar1.setValue(progress);
     System.out.println("Property changed");
    } 
}

//@Override
public void actionPerformed(ActionEvent e) {

}

  class Task extends SwingWorker<Void, Void> {
    @Override
    public Void doInBackground() {
        Random random = new Random();
        int progress = 0;
        setProgress(0);
        while (progress < 100) {
            try {
                Thread.sleep(random.nextInt(100));
            } catch (InterruptedException ignore) {}
            progress += random.nextInt(10);
            setProgress(Math.min(progress, 100));
        }
        return null;
    }

    /*
     * Executed in event dispatching thread
     */
    @Override
    public void done() {
        Toolkit.getDefaultToolkit().beep();
        setCursor(null); 
    }
}

I would like your help, I'm trying to scan my pc for JPEG images to count them. I have two problems, the first is that I'm using a jtable, but the results is never added until the program ends, and the progress bar isn't synchronized sometimes it ends before the program and sometimes after. please help me resolve these two problems and thank you.

Answer 1

You're using a SwingWorker in order to create a background thread -- good -- but you're making Swing calls directly from that background thread -- bad:

jProgressBar1.setValue(n);

Instead call setProgress(...) from within your SwingWorker, and add a PropertyChangeListener to the worker that listens for changes to the worker's "progress" bound property.

For examples:

• How do I make my SwingWorker example work properly?
• Cant get JProgressBar to update from SwingWorker class
• JProgressBar Tutorial

---

For an example of an mcve that shows an example of use of a JProgressBar with a SwingWorker:

import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.Random;
import java.util.concurrent.ExecutionException;
import javax.swing.*;

@SuppressWarnings("serial")
public class TestProgress2 extends JPanel {
   private JProgressBar progressBar = new JProgressBar(0, 100);
   private Action startBackgroundTaskAction = new StartBackgroundTaskAction();

   public TestProgress2() {
      progressBar.setStringPainted(true);
      add(progressBar);
      add(new JButton(startBackgroundTaskAction));
   }

   public void setActionEnabled(boolean enabled) {
      startBackgroundTaskAction.setEnabled(enabled);
   }

   private class StartBackgroundTaskAction extends AbstractAction {
      public StartBackgroundTaskAction() {
         super("Start Background Task");
         putValue(MNEMONIC_KEY, KeyEvent.VK_S);
      }

      @Override
      public void actionPerformed(ActionEvent e) {
         progressBar.setString(null);
         progressBar.setValue(0);
         setActionEnabled(false);
         MyTask myTask = new MyTask();
         myTask.addPropertyChangeListener(new MyTaskListener());
         myTask.execute();
      }
   }

   private class MyTaskListener implements PropertyChangeListener {
      @Override
      public void propertyChange(PropertyChangeEvent pcEvt) {
         MyTask myTask = (MyTask) pcEvt.getSource();
         if ("progress".equals(pcEvt.getPropertyName())) {
            int progress = myTask.getProgress();
            progressBar.setValue(progress);
         }
         if (pcEvt.getNewValue() == SwingWorker.StateValue.DONE) {
            setActionEnabled(true);
            progressBar.setString("Done");
            try {
               myTask.get();
            } catch (InterruptedException e) {
               e.printStackTrace();
            } catch (ExecutionException e) {
               e.printStackTrace();
            }
         }
      }
   }

   private class MyTask extends SwingWorker<Void, Void> {
      @Override
      protected Void doInBackground() throws Exception {
         Random random = new Random();
         int progress = 0;
         setProgress(0);
         while (progress < 100) {
             try {
                 Thread.sleep(random.nextInt(1000));
             } catch (InterruptedException ignore) {}
             progress += random.nextInt(10);
             setProgress(Math.min(progress, 100));
         }
         return null;
      }
   }

   private static void createAndShowGui() {
      TestProgress2 mainPanel = new TestProgress2();

      JFrame frame = new JFrame("TestProgress2");
      frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}