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Thread: New to SwingWorker how to use process?

  1. #1
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    Default New to SwingWorker how to use process?

    I'm new to multi-threads and am encountering an issue I can't figure out. I have built a simple class extending SwingWorker and all I want it to do is have it run a long running task in the doInBackground method. I also want to test the publish/process function so I attempted to have the process increment an int counter and display it on my GUI. Here is code:

    import java.util.concurrent.ExecutionException;
    import java.util.logging.Level;
    import java.util.logging.Logger;
    import javax.swing.SwingWorker;
     
    public class CounterWorker extends SwingWorker<Integer, Integer> {
     
        private MainGUI gui;
        private int counter;
     
        public CounterWorker(MainGUI gui) {
     
            this.gui = gui;
            this.counter = 0;
     
        }
     
        @Override
        protected Integer doInBackground() throws Exception {
     
     
            for (int i = 0; i < 100; i++) {
     
                counter++;
                publish(counter);
                Thread.sleep(10);
            }
     
            return 10;
        }
     
        protected void process(Integer count) {
     
            int c = count;
     
            gui.setCounterLabel(Integer.toString(c));
     
     
     
     
        }
     
        @Override
        protected void done() {
     
            gui.setStatusLabel("Finished");
            try {
                gui.setMainLabel(get().toString());
            } catch (InterruptedException ex) {
                Logger.getLogger(CounterWorker.class.getName()).log(Level.SEVERE, null, ex);
            } catch (ExecutionException ex) {
                Logger.getLogger(CounterWorker.class.getName()).log(Level.SEVERE, null, ex);
            }
     
        }
    }

    The doInBackground eventually is finished and done runs, but process never does anything (I don't see the counter). Is this even do-able? I appreciate the help.


  2. #2
    Super Moderator curmudgeon's Avatar
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    Default Re: New to SwingWorker how to use process?

    If you put an @Override annotation above your process method, your code won't compile, and that's because its method signature is wrong and doesn't override a parent method. The method should accept a List<Integer> parameter, not an Integer parameter. You should then iterate through the List<Integer> setting your counter label with it:

       @Override  // don't forget this
       protected void process(List<Integer> chunks) {
          for (Integer chunk : chunks) {
             // no need for the c variable
             gui.setCounterLabel(chunk.toString());
          }
       }

  3. #3
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    Default Re: New to SwingWorker how to use process?

    Everything makes sense now, thank you so much.

  4. #4
    Super Moderator curmudgeon's Avatar
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    Default Re: New to SwingWorker how to use process?

    You're quite welcome!

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