Java Interfaces: Using an Interface to Accomplish a Specific Goal

1. Java Interfaces: Using an Interface to Accomplish a Specific Goal Kirk Scott

2. Barley • From Wikipedia, the free encyclopediaJump to: navigation, searchFor other uses, see Barley (disambiguation).

3. Barley (Hordeumvulgare L.), a member of the grass family, is a major cereal grain. Important uses include use as animal fodder, as a source of fermentable material for beer and certain distilled beverages, and as a component of various health foods. It is used in soups and stews, and in barley bread of various cultures. Barley grains are commonly made into malt in a traditional and ancient method of preparation.

7. This is an introductory unit. • These are the units/chapters belonging to this section of the course: • Unit 16, Iterator, book chapter 28 • Unit 17, Template, book chapter 21 • Unit 18, Strategy, book chapter 23

8. What will be given next is an extremely brief overview of these topics. • Although the patterns are different from each other, they can be viewed as having this broad characteristic in common: • They make use of an interface to accomplish their goal • Iterator and Template both show how to make use of characteristics of the Java API

9. Iterator • Book definition: • The intent of the Iterator pattern is to provide a way to access the elements of a collection sequentially • Comment mode on: • Large parts of this should already be implicitly clear if you understood for each loops • You will see that this pattern is used by the Java API in dealing with collection classes

10. Template • Book definition: • The intent of the Template pattern is to implement an algorithm in a method, deferring the definition of some steps of the algorithm so that other classes can redefine them. • Comment mode on: • You will see that the template pattern is used in the Java API to support the ordering and sorting of objects in collection classes

11. Strategy • Book definition: • The intent of Strategy is to encapsulate alternative approaches, or strategies, in separate classes that each implement a common operation. • Comment mode on: • This pattern is actually quite simple • You can have multiple classes implementing the same interface—and thus the same method • The implementations of the methods may differ in the classes

12. In Summary and Mnemonic Devices: • Iterator: Remember Java collections • Template: Remember Java sorting • Strategy: Remember multiple classes implementing the same interface

13. The End