Learning Java Program

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
public class DynamicIconExample {
public static void main(String[] args) {
final JSlider width = new JSlider(JSlider.HORIZONTAL, 1, 150, 75);
final JSlider height = new JSlider(JSlider.VERTICAL, 1, 150, 75);
class DynamicIcon implements Icon {
public int getIconWidth() { return width.getValue(); }
public int getIconHeight() { return height.getValue(); }
public void paintIcon(Component c, Graphics g, int x, int y) {
g.fill3DRect(x, y, getIconWidth(), getIconHeight(), true);
}
};
Icon icon = new DynamicIcon();
final JLabel dynamicLabel = new JLabel(icon);
class Updater implements ChangeListener {
public void stateChanged(ChangeEvent ev) {
dynamicLabel.repaint();
}
};
Updater updater = new Updater();
width.addChangeListener(updater);
height.addChangeListener(updater);
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container c = f.getContentPane();
c.setLayout(new BorderLayout());
c.add(width, BorderLayout.NORTH);
c.add(height, BorderLayout.WEST);
c.add(dynamicLabel, BorderLayout.CENTER);
f.setSize(210,210);
f.setVisible(true);
}
}