无法从SwingWorker类更新JProgressBar

Question

I have my main GUI thread which has a JprogressBar in it and is implementing ProprtyChangeListener.

When a button is pressed, a different class, which extends SwingWorker, kicks into action and performs a series of potentially long calculations. I need the progress bar in class A to present the progress according to a variable in Class B.

My code is below (could be a bit messy with all my failed tries...)

Would appreciate any help.

GUI CLASS:

SignalSimulator signalSimulator = new SignalSimulator(
                path, numOfdataPoints, numOfLocalSpikes,
                    numOfExpSpikes, noiseAmp, slope, offset,
                                    rdbtnSineWave.isSelected());       
signalSimulator.addPropertyChangeListener( new PropertyChangeListener() {
    public void propertyChange(PropertyChangeEvent evt) {
        String property = evt.getPropertyName();
        if ("progress".equals(property)) {
            int progress = (Integer) evt.getNewValue();
            System.out.println("value in PropertChangeListener is: " + progress);
            progressBar.setValue(progress);
        }
    }
});
signalSimulator.execute(); 

Calculating class:

protected Integer doInBackground() throws Exception {
    if (isSine){
        data = generateSineWave(numOfDataPoints, noiseAmp, offset);
        data = addAnomalies(data, numOfPointOutliers, numOfExpSpikes);
    } else {
        data = generateLinearSignal(numOfDataPoints, noiseAmp, slope, offset);
        data = addAnomalies(data, numOfPointOutliers, numOfExpSpikes);
    }
    writeLogFile(path, ".txt", data);
    firePropertyChange("progress", 1, 1);
    setProgress((int)progress);
    publish(progress);
    System.out.println("value in doInBackground is: " + progress);
    return 1;
}

EDIT

Original problem remains. For some reason the progress bar is still not updating, I know for sure that the "progress" variable in progressBar.setValue(progress) is updating yet the progress bar in the GUI remains unchanged (fixed at 0) here is my new code:

GUI Class:

    SignalSimulator signalSimulator = new SignalSimulator(path, numOfdataPoints, numOfLocalSpikes, numOfExpSpikes, noiseAmp, slope, offset, rdbtnSineWave.isSelected());       
    signalSimulator.addPropertyChangeListener( new PropertyChangeListener() {
      public void propertyChange(PropertyChangeEvent evt) {
        String property = evt.getPropertyName();

        if ("progress".equals(property)) {
            int progress = (Integer) evt.getNewValue();
             System.out.println("value in PropertChangeListener is: " + progress);
             progressBar.setValue(progress);

        }
      }
    });
    signalSimulator.execute();

SwingWorker Class:

@Override
        protected Integer doInBackground() throws Exception {

            if (isSine){
                data = generateSineWave(numOfDataPoints, noiseAmp, offset);
                data = addAnomalies(data, numOfPointOutliers, numOfExpSpikes);
            }
            else{
                data = generateLinearSignal(numOfDataPoints, noiseAmp, slope, offset);
                data = addAnomalies(data, numOfPointOutliers, numOfExpSpikes);
            }

            writeLogFile(path, ".txt", data);

            return 1;}


public double[] generateSineWave(int numOfDataPoints, double noiseAmp, double offset){

            Random rnd = new Random();
            double[] dataArray = new double[numOfDataPoints];           


            for (int i=0;i<numOfDataPoints;i++){

                dataArray[i] =  Math.sin(Math.toRadians(i))+rnd.nextDouble()*noiseAmp+offset;
                progress = ((double)i)/(double)numOfDataPoints*100;

                //firePropertyChange("progress", 1, 1);
                setProgress((int)progress);
                //publish(progress);
                System.out.println("value in doInBackground is: " + progress);
            }

            return dataArray;           

EDIT Rewrote the whole thing without the extra (irrelevant) code. I guess I'm missing something basic here caus it still doesn't update the progress bar.

public class ProgressBarTest implements PropertyChangeListener {


    private JFrame frame;
    private JButton btnRun;
    static JProgressBar progressBar = new JProgressBar(0,100);

public static void main(String[] args) {

        EventQueue.invokeLater(new Runnable()  {
            public void run() {
                try {
                    //UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel"); 
                    UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); 
                    ProgressBarTest window = new ProgressBarTest();
                    window.frame.setVisible(true);
                    //SignalSimulator signalSimulator = new SignalSimulator();

                } catch (Exception e) {
                    e.printStackTrace();
                }

            }
        });
    }

/**
 * Create the application.
 */
public ProgressBarTest() {
    initialize();
}

private void initialize() {
    frame = new JFrame();
    frame.setBounds(100, 100, 450, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(null);
    frame.setResizable(false);  

    JProgressBar progressBar = new JProgressBar();
    progressBar.setAlignmentX(Component.RIGHT_ALIGNMENT);
    progressBar.setBounds(0, 252, 444, 20);
    progressBar.setStringPainted(true);
    frame.getContentPane().add(progressBar);


    JButton btnRun = new JButton("Start Long Run");
    btnRun.setBounds(167, 214, 159, 31);
    frame.getContentPane().add(btnRun);
    btnRun.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub
            longRun();
        }

    } );

}


private void longRun(){

    LongRunner longRunner = new LongRunner(100000);
    longRunner.addPropertyChangeListener(new PropertyChangeListener() {

        @Override
        public void propertyChange(PropertyChangeEvent evt) {

            if ("progress".equals(evt.getPropertyName())){
                int progress = (int) evt.getNewValue();
                System.out.println("Value in propertyChangeListener: "+progress);
                progressBar.setValue(progress);
            }
        }
    });
    longRunner.execute();
}
@Override
public void propertyChange(PropertyChangeEvent arg0) {
    // TODO Auto-generated method stub

}

}

And the SwingWorker:

import javax.swing.SwingWorker;


public class LongRunner extends SwingWorker<Integer, Double>{

    int numOfPoints;
    double progress;

    public LongRunner(int numOfPoints) {

        this.numOfPoints = numOfPoints;
        this.progress = 0;
    }

    private void runLong(int bigNum){

        for (int i=0; i< bigNum; i++){

            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            progress =  (((double)i*100)/(double)bigNum);
            setProgress((int)progress);
            System.out.println("Value in setProgress: "+progress);

        }

    }
    @Override
    protected Integer doInBackground() throws Exception {

        runLong(numOfPoints);
        return null;
    }

}

What am I doing wrong here?

Answer 1

You are calling doInBackground() directly from your code, something that is akin to calling run() directly in a runnable. This means that your code is not in fact running on a background thread, and so you are likely clobbering the event thread with long running code, preventing the Swing GUI, and your progress bar, from updating.

Solution: don't do this. Call execute() on your worker when you want it to run.

If you need further help, you're going to first have to help us. You understand that you have a ton of code posted, most of it completely unrelated to your problem at hand, and certainly more than you should ask volunteers to go through. Please get rid of all the extraneous unrelated code, and instead create and post a proper MCVE .

---

Edit
You also appear to be calling code directly from the EDT that should be left to your worker thread here:

        signalSimulator.execute();

        // ************* all these signalSimulator calls below ***********
        if (rdbtnSineWave.isSelected()) {
           data = signalSimulator.generateSineWave(numOfdataPoints,
                 noiseAmp, offset);
           data = signalSimulator.addAnomalies(data, numOfLocalSpikes,
                 numOfExpSpikes);
        } else { // Linear signal is selected
           data = signalSimulator.generateLinearSignal(numOfdataPoints,
                 noiseAmp, slope, offset);
           data = signalSimulator.addAnomalies(data, numOfLocalSpikes,
                 numOfExpSpikes);
        }

        signalSimulator.writeLogFile(path, ".txt", data);

You also appear to be creating only one worker object which is not proper since you can't re-use a SwingWorker object.

I suggest that you only create your SwingWorker object when it is needed, that you pass the information for what type of signal is needed into its constructor. This way the above methods can be called from the SwingWorker's doInBackground method where they belong.

eg,

signalSimulator = SignalSimulator(rdbtnSineWave.isSelected())
signalSimulator.addPropertyChangeListener(...);
signalSimulator.execute();

Note that you have some other significant unrelated problems in the code you've posted, but they will have to be addressed at some other time, but they include use of null layout and setBounds, almost always a very bad idea.

---

Edit

Just to clarify once again, your main problem is that you're calling long-running code on the Swing event thread. Just because a method is located in your Worker class does not mean that calling it will automatically have it run on a background thread. The only way to guarantee this is to have the code called from within your doInBackground() method. Again, what you want to do is to create your new worker object when it is needed , for instance, inside of some ActionListener, and at the time of its creation, pass into it all the information that it will need to run. Then add your PropertyChangeListener, then .execute() your worker. Do this, and I'll bet your code will work much better.

---

Edit
For example

import java.awt.event.*;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.Random;
import java.util.concurrent.ExecutionException;

import javax.swing.*;

public class ProgressExampleGui {
   private JPanel mainPanel = new JPanel();
   private JProgressBar progressBar = new JProgressBar();
   private JButton pressMeBtn  = new JButton(new MyAction("Press Me", KeyEvent.VK_P, this));

   public ProgressExampleGui() {
      progressBar.setStringPainted(true);
      progressBar.setString("");

      mainPanel.add(pressMeBtn);
      mainPanel.add(progressBar);
   }

   public void setProgress(int progress) {
      progressBar.setValue(progress);
      progressBar.setString(progress + "%");
   }

   public JComponent getMainComponent() {
      return mainPanel;
   }

   public void setEnabled(boolean enabled) {
      pressMeBtn.setEnabled(enabled);
   }

   private static void createAndShowGui() {
      ProgressExampleGui progExampleGui = new ProgressExampleGui();

      JFrame frame = new JFrame("Progress Example");
      frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
      frame.getContentPane().add(progExampleGui.getMainComponent());
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

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

@SuppressWarnings("serial")
class MyAction extends AbstractAction {
   private ProgressExampleGui gui;

   public MyAction(String name, int mnemonic, ProgressExampleGui gui) {
      super(name);
      putValue(MNEMONIC_KEY, mnemonic);
      this.gui = gui;
   }

   @Override
   public void actionPerformed(ActionEvent e) {
      AbstractButton source = (AbstractButton) e.getSource();
      gui.setProgress(0);
      source.setEnabled(false);
      MyWorker myWorker = new MyWorker();
      myWorker.addPropertyChangeListener(new WorkerPropChngListener(gui));
      myWorker.execute();
   }
}

class WorkerPropChngListener implements PropertyChangeListener {

   private ProgressExampleGui gui;

   public WorkerPropChngListener(ProgressExampleGui gui) {
      this.gui = gui;
   }

   @Override
   public void propertyChange(PropertyChangeEvent pcEvt) {
      MyWorker myWorker = (MyWorker) pcEvt.getSource();
      if ("progress".equals(pcEvt.getPropertyName())) {
         int progress = ((Integer)pcEvt.getNewValue()).intValue();
         gui.setProgress(progress);
      }

      if (SwingWorker.StateValue.DONE.equals(pcEvt.getNewValue())) {
         try {
            myWorker.get();
         } catch (InterruptedException | ExecutionException e) {
            e.printStackTrace();
         }
         gui.setEnabled(true);
      }
   }

}

class MyWorker extends SwingWorker<Void, Void> {
   private static final int MAX_INCR = 8;
   private static final long SLEEP_TIME = 200;
   private static final int MAX_VALUE = 100;
   private int value = 0;
   private Random random = new Random();

   @Override
   protected Void doInBackground() throws Exception {
      while (value < MAX_VALUE) {
         value += random.nextInt(MAX_INCR);
         value = Math.min(value, MAX_VALUE);
         Thread.sleep(SLEEP_TIME);
         setProgress(value);
      }
      return null;
   }
}

---

Edit
Regarding your new code, you've got two main problems:

Look at the results of your data output:

Value in setProgress: 0.0
Value in setProgress: 0.001
Value in setProgress: 0.002
Value in setProgress: 0.003
Value in setProgress: 0.004
Value in setProgress: 0.005
Value in setProgress: 0.006
Value in setProgress: 0.007
Value in setProgress: 0.008
Value in setProgress: 0.009
Value in setProgress: 0.01
Value in setProgress: 0.011
Value in setProgress: 0.012
Value in setProgress: 0.013
Value in setProgress: 0.014
Value in setProgress: 0.015
Value in setProgress: 0.016
Value in setProgress: 0.017
Value in setProgress: 0.018
Value in setProgress: 0.019
Value in setProgress: 0.02
Value in setProgress: 0.021
Value in setProgress: 0.022
Value in setProgress: 0.023
Value in setProgress: 0.024
Value in setProgress: 0.025
Value in setProgress: 0.026
Value in setProgress: 0.027
Value in setProgress: 0.028
Value in setProgress: 0.029

At the pace that this is going, your progress value will reach 1 and cause a visible change to the PropertyChangeListener and the JProgressBar when the next ice age is upon us. So first of all, change your sleep times, and change your big number to something more reasonable.

Next, you shadow important variables, notably your JProgressBar variable, progressBar. Here is where you declare it and initialize it in the class:

public class ProgressBarTest implements PropertyChangeListener {

   private JFrame frame;
   private JButton btnRun;
   static JProgressBar progressBar = new JProgressBar(0, 100);

As a side note, this variable should most definitely not be declared static , but that's not the cause of your current problem. The cause is that you in fact re-declare the same variable elsewhere in your initialize method, and then add this new object into your GUI:

private void initialize() {
  frame = new JFrame();

  // .....

  JProgressBar progressBar = new JProgressBar();

  // .....

  frame.getContentPane().add(progressBar);

Please understand that this new progressBar variable references a completely different JProgressBar, and so if you advance the value of the object created in the class, your GUI will show nothing because it is displaying a completely different object. To solve this, **don't redeclare and initialize a new variable in the initialize method. Instead use the object created in the class.

Other problems with your code: you use null layout and setBounds a lot. This will show to all that you are a newbie Swing programmer, since it means that you like to create rigid programs that are extremely difficult to upgrade, and that may not look good on all systems. Instead use the layout managers. For instance, here's your code with a few changes, all noted by comments:

import java.awt.*;
import java.awt.event.*;
import java.beans.*;

import javax.swing.*;

//!! no need to implement PropertyChangeListener
//!! public class ProgressBarTest implements PropertyChangeListener {
public class ProgressBarTest2 {
   private JFrame frame;
   private JButton btnRun;

   // !! this shouldn't be static!
   // !! static JProgressBar progressBar = new JProgressBar(0, 100);
   private JProgressBar progressBar = new JProgressBar(0, 100); // !!

   public static void main(String[] args) {
      EventQueue.invokeLater(new Runnable() {
         public void run() {
            try {
               UIManager
                     .setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
               ProgressBarTest2 window = new ProgressBarTest2();
               window.frame.setVisible(true);
            } catch (Exception e) {
               e.printStackTrace();
            }
         }
      });
   }

   public ProgressBarTest2() {
      initialize();
   }

   private void initialize() {
      frame = new JFrame();
      // !!frame.setBounds(100, 100, 450, 300);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      //!! frame.getContentPane().setLayout(null); //!! never use null layouts
      frame.setResizable(false);

      // !! don't create a shadowed variable
      // !! JProgressBar progressBar = new JProgressBar();

      progressBar.setAlignmentX(Component.RIGHT_ALIGNMENT);
      //!! progressBar.setBounds(0, 252, 444, 20);
      progressBar.setStringPainted(true);
      //!! frame.getContentPane().add(progressBar);
      frame.getContentPane().add(progressBar, BorderLayout.SOUTH);
      btnRun = new JButton("Start Long Run"); //!! no shadowing
      //!! btnRun.setBounds(167, 214, 159, 31);
      JPanel panel = new JPanel(); //!!
      panel.setPreferredSize(new Dimension(450, 300)); //!!
      panel.setLayout(new GridBagLayout()); //!!
      panel.add(btnRun); //!!
      frame.getContentPane().add(panel, BorderLayout.CENTER); //!!
      btnRun.addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
            longRun();
         }
      });

      //!!
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   private void longRun() {
    //!! use a more realistic value, one that should show change in listener
      //!! LongRunner longRunner = new LongRunner(100000);
      LongRunner2 longRunner = new LongRunner2(10000);  
      longRunner.addPropertyChangeListener(new PropertyChangeListener() {
         @Override
         public void propertyChange(PropertyChangeEvent evt) {
            if ("progress".equals(evt.getPropertyName())) {
               int progress = (int) evt.getNewValue();
               System.out.println("Value in propertyChangeListener: "
                     + progress);
               progressBar.setValue(progress);
            }
         }
      });
      longRunner.execute();
   }

   // !! @Override // !! not needed
   // public void propertyChange(PropertyChangeEvent evt) {
   // }
}

class LongRunner2 extends SwingWorker<Integer, Double> {
   private static final long SLEEP_TIME = 15; // !!
   int numOfPoints;
   double progress;

   public LongRunner2(int numOfPoints) {
      this.numOfPoints = numOfPoints;
      this.progress = 0;
   }

   private void runLong(int bigNum) {
      for (int i = 0; i < bigNum; i++) {
         try {
            // !! quicker turn-over so that our bigNum can change
            // in a realistic way
            // !! Thread.sleep(100);
            Thread.sleep(SLEEP_TIME);// !!
         } catch (InterruptedException e) {
            e.printStackTrace();
         }
         progress = (((double) i * 100) / (double) bigNum);
         setProgress((int) progress);
         // !! System.out.println("Value in setProgress: " + progress); //!! This will slow us down
      }
   }

   @Override
   protected Integer doInBackground() throws Exception {
      runLong(numOfPoints);
      return null;
   }
}