import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class HelloWorld
{
  public static void main(final String[] args)
    {
        System.out.println("executing main");
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new HelloWorld();
            }
        });
    } 
    
    public HelloWorld()
    {
        System.out.println("HelloWorld constructor");
        
        final JFrame frame = new JFrame("HelloWorld");
        frame.setLayout(new BorderLayout(20, 20));
        
        JButton button = new JButton("Press Me");
        button.setPreferredSize(new Dimension(200, 50));
        button.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                System.out.println("about to construct JFileChooser");
                JFileChooser fileChooser = new JFileChooser();
                fileChooser.showOpenDialog(frame);
            }
        });
        
        frame.add(button, BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
    }

        }