Ch 4: Objects & Classes

Ch 4: Objects & Classes

1. OOP: Creating a model that resembles real-life situation

2. OBJECT

   • FIELDS
     • Variables; can be primitives or references to objects
   • METHODS
     • Define actions that a class's object can do
     • DECLARATION
       • Consists of return value, method name, & a list of arguments
         • Return type can be:
           • Primitive
           • An object
           • Void
             • Method returns nothing
             • Null
               • Nothing
     • BODY
       • Contains code that perform action
         • Types of Actions
           • Create
           • Read
           • Update
           • Delete
     • The Method Main
       • Provides the entry point to an application - only one of the classes needs to have one
   • An element that corresponds to the properties of a specific class
   • DATA TYPES
     • Primitive/SImple
       • Boolean
         • T/F
       • Int
         • ..-1000..0..1000...
       • Double
         • 3.14159265
       • Char
         • 'a' 'b' 'c'
     • Composite/Complex
       • String
         • Words & Sentences

3. CLASS

   • Blueprint/Template to create objects of identical type - all program elements reside in a class
   • When writing a class, consider:
     • Class Name
     • Fields
     • Methods
   • CONSTRUCTOR
     • Used to construct an object - looks like a method, however does not have a return value
       • Every class needs at least 1
   • General scenario - represents an element from problem's world/context