FirstTask

FirstTask

1. Object Oriented Program

   • What is an object?
     • An object is an instance of a class
       • Attributes are also called Fields
         • Primitives
         • Reference to objects
         • How to name fields?
           • Use camel naming convention: capitalize every word expect the first one
       • Actions are also called methods
         • How to declare methods?
           • returntype-----methodname---(list of arguments)
             • A return type can be a primitive, an object or void
               • A "main" method is a special method that provides an entry to an application
                 • It allows the class containing it to be invoked
                   • How to declare a main method?
                     • public static void main (String[] args)
                   • Only 1 main method is required in an application
                     • Only arguments accepted are strings
         • Constructors methods are used to construct objects.
           • Every class needs to have it; if not manually provided, the compiler adds one
             • How to declare a constructor method?
               • constructorname (list of arguments) { [body ] }
                 • Named after class name
                 • If it has not arguments it is called a "no argument constructor"
                 • Constructor arguments can be used to initialize the fields of the object
             • Constructor methods have no return type: not even void
       • An object can have an attribute or an action or both or neither
   • What is a Class?
     • Classes are tools programmer use to create an abstraction
     • Building blocks of Java
     • How to declare a class?
       • Use class + name to declare a class
         • Use Pascal Convention: Capitalize the first letter of every word
     • How to represent a class using a UML diagram?
       • Create a rectangle with 3 parts: Name(top), fields(middle), methods(bottom)