code in blog.sheimi.me: 2012-06-20-software-architecture-review-4 (3)

Decorator.java

// Problem

abstract class VisualComponent {
  void draw();
  void resize();
}
class TextView extends VisualComponent {
  void draw() {...}
  void resize() {...}
}
class StreamVidoView  VisualComponent {
  void draw() {...}
  void resize() {...}
}

// Answer

abstract class Decorator extends VisualComponent {
  VisualComponent vc;
  Decorator(VisualComponent vc) {this.vc = vc;}
  void draw() {vc.draw();}
  void resize() {vc.resize();}
}

abstract class Border extends Decorator {
  void draw() {super.draw(); drawBorder();}
  abstract void drawBorder();
}

class PlainBorder extends Border {
  void drawBorder() {...}
}

...