You have a misundertanding about how SwingWorker
works. This class is intended to provide a way to update the GUI while heavy tasks are being performed. All of this is because Swing
components updates take place in the Event Dispatch Thread (a.k.a. EDT) which is a particular thread.
For instance, if you click a button and perform a time consuming task all in the EDT, then this thread will block untill this task finishes. Consequently, you'll see your GUI is frozen.
Keeping this in mind, doInBackground() method runs in another different thread that's not the EDT which is ok. So don't call any Swing
method in there:
protected Integer doInBackground() throws Exception{
//Downloads and unzips the first video.
if(cameraBoolean==true) // just use if(cameraBoolean), since this is a boolean
panel.add(this.downloadRecording(camera, recording)); // NO!
else
panel.add(new JLabel("Could not contact camera "+camera.getName())); //NO!
panel.repaint(); //NO, never!
jframe.repaint();//NO, never!
return 1;
}
Add a JLabel
to this panel
before executing your SwingWorker
and update its text using publish() and process() methods instead:
JPanel panel = new JPanel();
final JLabel progressLabel = new JLabel("Some text before executing SwingWorker");
panel.add(progressLabel);
SwingWorker<Integer, String> worker = new SwingWorker<Integer, String>() {
@Override
protected Integer doInBackground() throws Exception {
if(cameraBoolean){
pubish("Starting long process...");
//Some processing here
publish("Intermediate result to be published #1");
//Some other processing stuff
publish("Intermediate result to be published #2");
//And so on...
return 0;
} else {
publish("Could not contact camera "+camera.getName());
return -1;
}
}
@Override
protected void process(List<String> chunks) {
for(String string : chunks){
progressLabel.setText(string);
}
}
@Override
protected void done() {
progressLabel.setText("Finished!!!");
}
};
worker.execute();
Both process()
and done() methods take place in the EDT so it's safe make GUI updates there. Take a look to this excelent example: Swing Worker Example for more details.