Chapter 9 Classes & Objects

Objectives Explain encapsulation. Explain the purpose of inheritance. Explain the purpose of overriding and overloading. Create and explain the use of constructors. Use setter and getter methods. Create a basic UML diagram. Create a program that inherits properties from another program.

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.

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.

Object-Oriented Programming Concepts Encapsulation - lets you create a class template for creating objects. It is the process of hiding the attributes of a class and making them accessible via the object’s methods. 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

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

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( ) { }

Alice Setters and Getters

Unified Modeling Language (UML)

Class Template

Application to Run Class Template