4. Objects and Classes

4. Objects and Classes

1. Objects

   • a created model that resembles a real-life situation to solve an issue.  ex. objects of a company payroll application - Company, Employee, Tax
   • Classes
     • We need classes to create Java objects which is similar to blueprints or a design template. The class determines the object.  Classes are an OOP tool that enable programmers to create the abstraction of a problem.  class className {         [class body]} Pascal Naming - Capitalize the initial of each word - PostOffice
     • fields
       • camel naming - capitalize the initial of each word, except the first word. - same for Methods
       • methods
         • Methods define actions that a class's objects can do. 
         • declarations
           • return value, the method name, a list of arguments returnType methodName (listOfArguments) ex1. double getSalary()  <- getSalary method that returns a double, no arguments ex2. Address getAdress () <- a method that returns an Address oject  ex3. int negate(int number)  <- 
           • body
             • The body contains code that perform the action.
     • UML - class name
       • list of fields
         • list of methods
     • constructor
   • attributes
     • actions
   • instance
     • new