Adapter%20Pattern

1
Adapter Pattern

• This presentation will probably involve audience
  discussion, which will create action items. Use
  PowerPoint to keep track of these action items
  during your presentation
• In Slide Show, hold down the control key and
  click the mouse button
• Select Meeting Minder
• Select the Action Items tab
• Type in action items as they come up
• Click OK to dismiss this box
• This will automatically create an Action Item
  slide at the end of your presentation with your
  points entered.

• by
• Manish Shah Eugene Park
• CSPP 523
• Jan.21, 2002

2
Scenario

• Outlets and Plugs
• Outlets in the US require a certain type of
  plug.
• For example, a plug made in Europe for a
  European outlet, may not fit in an outlet in the
  US.
• To use this appliance in the US, one would need
  to purchase an adapter.

3
Overview

• Structural Patterns
• Patterns that describe how we can form larger
  structures from classes or objects.
• The Adapter Pattern is a structural pattern which
  can be a class or an object pattern.
• Class patterns use inheritance to compose
  classes.
• Object patterns use object composition.

4
Lets Break it down...

• This pattern lets classes work together that
  normally would not because their interfaces were
  incompatible.
• Example TextShape and TextView

5
Structure of the Adapter Pattern

• Object Adapter

• Example
• Target is Shape
• Client is Drawing Editor
• Adaptee is TextView
• Adapter is TextShape

6
Structure of the Adapter Pattern

• Class Adapter

7
Implementation

• myStack Adapter Pattern is an Object Pattern
• abstract class Stack
• abstract Object top()
• abstract Object pop()
• abstract void push(Object v)
• public class myStack
  Adapter class
• private Vector stack new Vector()
  Adaptee object
• public boolean empty() return stack.size()
  0
• pubic Object top() return stack.lastElement()
  
• public Object pop()
• Object rslt stack.lastElement()
• stack.removeElementAt(stack.size()-1)
• return rslt
• void push(Object v) stack.addElement(v)

Target class
8
Implementation continued

• myStudent Adapter Pattern is a Class Adapter
• abstract class Student
  Target class
• abstract void enroll()
• ...
• public class ArchaicStudent
  Adaptee class
• public void xyz()
• ...
• ...
• public class myStudent extends ArchaicStudent
  Adapter class
• public void enroll()
• this.xyz()
• ...