Object Oriented Programming

Object Oriented Programming

1. Java Object

   • Attributes/fields and Actions/methods
   • to create an object from a class "new" is always followed by the construtor of the class to be instantiated

2. Java Classes

   • template for objects
     • class determines object
   • class name, the fields, the methods
     • Ex. Employee, Boss, DateUtility, PostOffice, RegularRateCalculator
     • Methods (responsibilities)
       • define actions that a class's objects can do
         • declaration: return value, method name, list of arguments
           • body: contains code that performs the action
             • Examples
               • returnType methodName (listOfArguments)
                 • double getSalary ( )
                   • Address getAddress ( )
                     • int negate (int number)
                       • this method accepts an argument
                       • int add(int a, int b)
                         • this method takes more than one argument
     • Fields
       • a variable; can refer to another object
       • Ex. address, validAddress, numberOfRows
   • Constructors: used to construct an object, every class must have
     • constructorName (listofArguments) { [constructor body] }