Re: [SWING] Join thread with SwingWorker objects

Here's what I came up with:

package swingthreads;

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;

public class Main
{

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

    private static void createGui()
    {
       final ExampleFrame frame = new ExampleFrame();
       final Executor exe = Executors.newFixedThreadPool( 5 );

       ActionListener batchKicker = new ActionListener()
       {

          public void actionPerformed( ActionEvent e )
          {
             ExampleWorker worker = new ExampleWorker( exe, 5, frame.
                     getOutput() );
             worker.execute();
          }
       };

       frame.addButtonListener( batchKicker );
       frame.setVisible( true );
    }
}

class ExampleFrame
         extends JFrame
{

    JTextArea output;
    JButton button;

    public ExampleFrame()
    {
       super( "Example Batch Threads" );
       output = new JTextArea();
       JScrollPane sp = new JScrollPane( output );
       add( sp );
       button = new JButton( "Start" );
       JPanel panel = new JPanel( new FlowLayout( FlowLayout.CENTER ) );
       panel.add( button );
       add( panel, BorderLayout.SOUTH );
       setLocationRelativeTo( null );
       setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
       setSize( 300, 300 );
    }

    public JTextArea getOutput()
    {
       return output;
    }

    public void addButtonListener( ActionListener a )
    {
       button.addActionListener( a );
    }
}

class ExampleWorker
         extends SwingWorker<Void, Void>
{

    Executor exe;
    JTextArea output;
    int tasks;

    public ExampleWorker( Executor exe,
            int tasks, JTextArea output )
    {
       this.exe = exe;
       this.tasks = tasks;
       this.output = output;
    }

    @Override
    protected Void doInBackground()
            throws Exception
    {
       CountDownLatch latch = new CountDownLatch( tasks );
       for( int i = 0; i < tasks; i++ ) {
          ExampleBatchTask batch =
                  new ExampleBatchTask( output, latch );
          exe.execute( batch );
       }
       latch.await();
       return null;
    }

    @Override
    public void done()
    {
       output.append( "All done!\n" );
    }
}

class ExampleBatchTask
         implements Runnable
{

    JTextArea output;
    CountDownLatch latch;

    public ExampleBatchTask( JTextArea output, CountDownLatch latch )
    {
       this.output = output;
       this.latch = latch;
    }

    public void run()
    {
       int interval = (int) (Math.random() * 4 + 1);
       // append() is thread safe!
       output.append( "Started: " + interval + "\n" );
       for( int i = 0; i < 5; i++ ) {
          try {
             Thread.sleep( interval * 1000 );
          } catch( InterruptedException ex ) {
             break; // exit immediately if interrupted
          }
          output.append( "running " + interval + "\n" );
       }
       latch.countDown();
    }
}