import java.awt.*;
import javax.swing.*;

public class ShowSpringLayout extends JApplet {
  public ShowSpringLayout() {
    SpringLayout springLayout = new SpringLayout();
    JPanel p1 = new JPanel(springLayout);
    JButton jbt1 = new JButton("Button 1");
    p1.add(jbt1);

    Spring spring = Spring.constant(0, 1000, 2000);
    springLayout.putConstraint(SpringLayout.WEST, jbt1, spring,
                               SpringLayout.WEST, p1);
                             springLayout.putConstraint(SpringLayout.EAST, p1,
                               Spring.sum(spring, spring), SpringLayout.EAST, jbt1);
    springLayout.putConstraint(SpringLayout.NORTH, jbt1, spring,
                               SpringLayout.NORTH, p1);
    springLayout.putConstraint(SpringLayout.SOUTH, p1, spring,
                               SpringLayout.SOUTH, jbt1);

    add(p1, BorderLayout.CENTER);
  }

  public static void main(String[] args) {
    ShowSpringLayout applet = new ShowSpringLayout();
    JFrame frame = new JFrame();
    //EXIT_ON_CLOSE == 3
    frame.setDefaultCloseOperation(3);
    frame.setTitle("ShowSpringLayout");
    frame.getContentPane().add(applet, BorderLayout.CENTER);
    applet.init();
    applet.start();
    frame.setSize(400,320);
    Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
    frame.setLocation((d.width - frame.getSize().width) / 2,
      (d.height - frame.getSize().height) / 2);
    frame.setVisible(true);
  }
}