0.2 Encapsulation - the big picture

Table of contents

• Preface
  • General
  • Viewing tip
    • Figures
    • Listings
  • Supplemental material
• General background information
  • Abstraction
  • Encapsulation
• Preview
• Discussion and sample code
• Run the program
• Resources
• Complete program listings
• Miscellaneous

Preface

General

This tutorial lesson is part of a series of lessons dedicated to object-oriented programming (OOP) with ActionScript .

The three main characteristics of an object-oriented program

Object-oriented programs exhibit three main characteristics:

• Encapsulation
• Inheritance
• Polymorphism

In this and the next two lessons, I will explain and illustrate these three characteristics from a big-picture viewpoint. Following that, I will getdown in the weeds and start explaining in detail how to use ActionScript for object-oriented programming (OOP) .

Several ways to create and launch ActionScript programs

There are several ways to create and launch programs written in the ActionScript programming language. Many of the lessons in this series willuse Adobe Flex as the launch pad for the sample ActionScript programs.

An earlier lesson titled The Default Application Container provided information on how to get started programming with Adobe's Flex Builder 3. (See Baldwin's Flex programming website .) You should study that lesson before embarking on the lessons in this series.

Some understanding of Flex MXML will be required

I also recommend that you study all of the lessons on Baldwin's Flex programming website in parallel with your study of these ActionScript lessons. Eventually youwill need to understand both ActionScript and Flex and the relationships that exist between them in order to become a successful ActionScript programmer.

Will emphasize ActionScript code

It is often possible to use either ActionScript code or Flex MXML code to achieve the same result. Insofar as this series of lessons is concerned,the emphasis will be on ActionScript code even in those cases where Flex MXML code maybe a suitable alternative.

Viewing tip

I recommend that you open another copy of this document in a separate browser window and use the following links to easily find and view the figures andlistings while you are reading about them.

Figures

• Figure 1 . Screen output for Encapsulation01.
• Figure 2 . File structure for the project named Encapsulation01.

Listings

• Listing 1 . Mxml code to instantiate two custom component objects.
• Listing 2 . Beginning of the class named QuizA.
• Listing 3 . Beginning of the class named QuizB.
• Listing 4 . Implicit setter methods for QuizA.
• Listing 5 . Implicit setter methods for QuizB.
• Listing 6 . Constructor for QuizA.
• Listing 7 . Constructor for QuizB.
• Listing 8 . The checkButtonHandler for QuizA.
• Listing 9 . The checkButtonHandler for QuizB.
• Listing 10 . The vboxCompleteHandler for QuizA.
• Listing 11 . The vboxCompleteHandler for QuizB.
• Listing 12 . Source code for Encapsulation01.mxml.
• Listing 13 . Source code for QuizA.as.
• Listing 14 . Source code for QuizB.as.