Design Patterns Explained

246 Part V • Handling Variations with Design Patterns
Example 15-1 Java Code Fragment: Decorator
class SalesTicket extends Component
{ public void prtTicket () {
// sales ticket printing code here
}
abstract class Decorator extends Component
{ private Component myComp; public Decorator
(Component myC) { myComp= myC;
}
public void prtTicket () { if
(myComp != null)
myComp.prtTicket(); }
}
class Headerl extends Decorator
{ public void prtTicket () {
// place printing header 1 code here
super.prtTicket(); } }
class Header2 extends Decorator
{ public void prtTicket () {
// place printing header 2 code here
super.prtTicket(); } }
class Footerl extends Decorator
{ public void prtReport ()
{ super.prtTicket();
// place printing footer 1 code here } }
class Footer2 extends Decorator
{ public void prtReport ()
{ super.prtTicket();
// place printing footer 2 code here } }
class SalesOrder { void
prtTicket () {
(continued)