Object Oriented Design

c) You review a design written by somebody else for an application and you find these:

- an interface Shape with a method draw() - a class Circle that implements Shape - a class Rectangle that implements Shape - a class CompoundShape that: o implements interface Shape o aggregates 0 or more Shape objects, o has an extra method called add(Shape sh) o for implementing method draw() calls the draw() method for all aggregated Shape objects. You assume that a CompoundShape object is made of multiple shapes. What design pattern is at work in this application? Explain your answer.

d) The TitledBorder class can give a title to a border. Consider the code

panel.setBorder(new TitledBorder(new EtchedBorder(), "Enter Option"));

What design pattern(s) are at work? Explain your answer. (a similar example is in the textbook/notes)