Design Patterns Java™ Workbook

Appendix B. Solutions

Figure B.9. In this design, components that depend on the slider implement

ChangeListener so that they can register for slider events.

SOLUTION 9.3.......................................................................................................................................

One solution is:

package com.oozinoz.applications;
import javax.swing.;
import java.util.;
import com.oozinoz.ballistics.Tpeak;
public class BallisticsLabel extends JLabel
implements Observer
{

public BallisticsLabel(Tpeak tPeak)
{
tPeak.addObserver(this);
}

public void update(Observable o, Object arg)
{
setText("" + ((Tpeak) o).getValue());
repaint();
}
}

Note that this solution places the Tpeak class in the ballistics package and
the BallisticsLabel class in the applications package.