ECS510 Algorithms and Data Structures in an Object-Oriented Framework (“ADSOOF”)

The Ducks example

This is the code, given as Java files, from John Brewer's paper Why a Duck?.

• Duck1.java  A class with method quack()
• Example1.java  Demonstrating Duck1
• DuckCall1.java  Another class with method quack()
• Example2.java  Demonstrating Duck1 and DuckCall1
• Quackable.java  An interface type, covering any class that has method quack()
• Duck2.java  A class with method quack() annotated to implement Quackable
• DuckCall2.java  Another class with method quack() annotated to implement Quackable
• Example3.java  Demonstrating a variable of type Quackable used to call quack() on two objects of different classes which implement Quackable
• QuackFactory1.java  A class which produces Quackable objects from a static factory method
• Example4.java  Demonstrating QuackFactory1
• QuackDecorator.java  A class which “decorates” a Quackable object to count the number of calls of the quack() method
• Example5.java  Demonstrating QuackDecorator
• QuackFactory2.java  A class which produces decorated Quackable objects from a static factory method
• Example6.java Demonstrating QuackFactory2
• QuackComposite.java  A class which holds a collection of Quackable objects, implements Quackable, and implements quack() by calling quack() on all the Quackable objects in the collection
• Example7.java  Demonstrating QuackComposite
• Goose.java  A class which doesn't have a quack() method but does have a honk() method
• GooseAdapter.java  A class which implements Quackable by converting a quack() call to a honk() call
• Example8.java  Demonstrating GooseAdapter
• NullQuackable.java  A class which implements Quackable by a quack() call which does nothing
• Example9.java  Demonstrating NullQuackable and the other classes introduced here

Here are some more files, which weren't in the Brewer paper, but use the same example to demonstrate another design pattern concept, the Factory Object:

• QuackFactory3.java  A class for factory objects which produce Quackable objects with a name set by the factory
• Example10.java  Demonstrating QuackFactory3

Why “Why a Duck?”?

Film buffs will, of course, know, but in case you were wondering, the title of Brewer's paper comes from what is perhaps the most well-known scene in any of the Marx brothers' films. It is in the film “The Cocoanuts”, script here, clip here.

Last modified: 16 July 2019