import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.*;

public class GUIExample6
{
    public static void main(String[] args)
    {
        JFrame jframe = new JFrame("Hello There");
        
        JOptionPane.showMessageDialog(jframe, "Here we go...");
        
        JLabel jlabelNorth = new JLabel("at the top");
        JLabel jlabelSouth = new JLabel("at the bottom");
        JLabel jlabelEast = new JLabel("east");
        JLabel jlabelWest = new JLabel("west");
        
        jlabelSouth.setHorizontalAlignment(SwingConstants.CENTER);
        jlabelNorth.setHorizontalAlignment(SwingConstants.CENTER);
        
        jlabelSouth.setPreferredSize(new Dimension(0, 100));
                
        jframe.add(jlabelNorth, BorderLayout.NORTH);
        jframe.add(jlabelSouth, BorderLayout.SOUTH);
        jframe.add(jlabelEast, BorderLayout.EAST);
        jframe.add(jlabelWest, BorderLayout.WEST);
        
        JPanel jpanel = new JPanel(new GridLayout(4, 5));
        jframe.add(jpanel, BorderLayout.CENTER);
        
        class Buttoner implements ActionListener {
            int i;
            public Buttoner(int i) { this.i = i; }
            public void actionPerformed(ActionEvent e) {
                System.out.format("button %d pressed\n", i);
            }
        }
        
        for (int i = 0; i < 20; i++) {
            JButton jbutton = new JButton("B" + i);
            jbutton.addActionListener(new Buttoner(i));
            jpanel.add(jbutton);
        }
        
        jframe.pack();
        
        jframe.setLocationRelativeTo(null);
        jframe.setVisible(true);
    }
}