OBJECTS and CLASSES

OBJECTS and CLASSES

1. Objects

   • An entity that can be identified

2. Class

   • The blueprint of method used

3. Unified Modeling Language (UML)

   • a set of standard diagrams for graphically depicting object-oriented systems

4. Constructors

   • Initialize an object’s data.
   • Can be overloaded, to construct objects with different initial data values.
   • MUST have the same name as the class itself
   • DO NOT have a return type – not even void
   • Invoked using the new operator when an object is created
     • Rectangle rectTwo = new Rectangle(“Yellow”, 2.5, 11.6);

5. Accessing an Object’s Data and Methods

   • data can be accessed and its method invoked(using dot operator)

6. A Demo Program

   • We need a demo program to test a class program
   • It must be saved in the same folder or directory

7. Modifiers

   • Control access to data, methods and classes
   • Introduces the public, private and default modifiers
     • public - classes, methods, and data fields can be accessed from any other classes
     • private - methods and data fields can be accessed only from within its defining
     • If public and private is not used, then by default the classes, methods and data are accessible by any class in the same package
       • Known as package-private or package-access

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