Chapter 6

Classes & Objects

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Class•A class defines a particular kind of object.•Each class is a blueprint that tells Alice exactly how to

create and display an object.•Classes begin with a capital letter.

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Objects

•When an object is created and displayed, we call this instantiating the class because an object is an instance of that class.

•Object names begin with a lowercase letter.

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Object-Oriented Programming Concepts • Encapsulation - lets you create a program (class) that

describes data and methods that you want to use as a template to create objects. 

• Inheritance - enables you to create a class that is similar to a previously defined class, but one that still has some of its own properties. 

• Polymorphism – allows you to create new objects that perform the same methods as the base object but which perform one or more of these functions in a different way.  ▫ Overloading▫ Overriding

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Declaring Objects

•Cow cow1 = new Cow ( ……..);•Adult emily = new Adult ( …..);•Button clearButton = new Button ( );

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Constructor

•A constructor is a method with the same name as the class (including case sensitivity).  

•A class can contain several constructors to provide a variety of means for initializing objects of that class.  MyFishy nemo =  new MyFishy( );

public MyFishy( ) { }

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Alice Setters and Getters