Call a function after a Thread is completed

i'm writing a Sftp-client program using Jsch. I am using JProgressBars to display the Progress of Uploads and Downloads. My GUI contains Buttons according to the files in my Working Directory. When i delete a file i updated my gui to give the user a feedback:

void update() {
    panel.removeAll();
    addToPanel(ls(channelsftp, sftpWorkingDir));
    validate();
}

This is using my ls-function to return all Files in the current workingDir. addToPanel will process the lsEntries to output Buttons on the panel. This works great for deleting files. However, i want the same update-function to be called after an upload is completed. Since upload is giving me graphical feedback in the form of a JProgressBar its functionality was moved to a thread:

final JFileChooser uploadChooser = new JFileChooser();
    ulo.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent arg0) {
            int returnVal = uploadChooser.showOpenDialog(Navigator.this);
            if(returnVal == JFileChooser.APPROVE_OPTION) {
                String pathToUpload = uploadChooser.getSelectedFile().getAbsolutePath();
                Runnable uploadIt = new UploadUtil(pathToUpload, chacha);
                new Thread(uploadIt).start();
            }   
        }
    });

So after the user clicks on OK in this JFileChooser the upload starts. Here is UploadUtil:

public class UploadUtil implements Runnable{

    String paTU;
    ChannelSftp csftp;

    public UploadUtil(String pathToUl, ChannelSftp chaSftp) {
        paTU = pathToUl;
        csftp = chaSftp;
    }

    @Override
    public void run() {
        try {
            csftp.put(paTU, LoginAndFunctions.sftpWorkingDir, new SystemOutProgressMonitor());
        } catch (SftpException e) {
            Error errorUploading = new Error(e.toString()+"\nUploadpipe closed unexpectedly");
            errorUploading.setVisible(true);
        }
    }
}

SystemOutProgressMonitor is a class that processes datatransfer in Jsch. I tried using Thread.join() and CountDownLatch. Both prevented my JProgressBar from updating. Is there a different solution for it?

A solution is to use a call back method or mechanism. Since this is a Swing problem, use a SwingWorker, not a Runnable in a thread which gives you two potential ways

• The done() method is called within the worker on the Swing event thread when it has completed its job.
• Or add a PropertyChangeListener to the SwingWorker, listen to the "state" property, and react when the new value is SwingWorker.StateValue.DONE.

Note that you can also add a PropertyChangeListener to the worker thread and listen to its progress property. Within the worker as it's updating your data, update this property by calling setProgress(int value) with a value from 0 to 100. Then in the listener, update your JProgressBar with this value.

For example (Note that code not tested yet, so sorry if there are errors):

public class UploadUtil extends SwingWorker<Void, Void> {

    String paTU;
    ChannelSftp csftp;

    public UploadUtil(String pathToUl, ChannelSftp chaSftp) {
        paTU = pathToUl;
        csftp = chaSftp;
    }

    @Override
    public void doInBackground() throws Exception {
        try {
            csftp.put(paTU, LoginAndFunctions.sftpWorkingDir, new SystemOutProgressMonitor());
        } catch (SftpException e) {
            Error errorUploading = new Error(e.toString()+"\nUploadpipe closed unexpectedly");
            errorUploading.setVisible(true);
        }
    }
}

A listener for your worker:

class UploadUtilListener implements PropertyChangeListener {
    public void propertyChanged(PropertyChangeEvent e) {
        if (e.getNewValue() == SwingWorker.StateValue.DONE) {
            // do your code here that you want called when worker done
        }
    }
}

then to use it:

public void actionPerformed(ActionEvent arg0) {
    int returnVal = uploadChooser.showOpenDialog(Navigator.this);
    if(returnVal == JFileChooser.APPROVE_OPTION) {
        String pathToUpload = uploadChooser.getSelectedFile().getAbsolutePath();
        UploadUtil uploadIt = new UploadUtil(pathToUpload, chacha);
        uploadIt.addPropertyChangeListener(new UploadUtilListener());
        uploadIt.execute();
    }   
}