ppt 4

• Object-oriented paradigm


  To design the program using classes and objects
• Object


  • Related to real-world entities such as book, house, pencil, etc.
  • Focuses on writing the reusable code
  • Widespread technique to solve problems by creating objects
• Major principles of object-oriented programming


  • Class
  • Object
  • Method
  • Inheritance
  • Polymorphism
  • Data Abstraction
  • Encapsulation
• Class


  • A blueprint from which an object is constructed by the computer
  • Describes the methods (functions) and properties (variables) that will exist in an object when it's created
• Instantiation


  The process of creating an object of a class in memory
• Instance


  An object that is built from a class and contains real data
• Class attributes

  Variables within a class
• Method


  • A block of code which only runs when it is called
  • Used to perform certain actions
  • Allows code reuse
• Parameters


  Information passed to methods, acting as variables inside the method
• Arguments


  Values passed to parameters when a method is called
• Constructor


  • A special method used to initialize objects
  • Called when an object of a class is created
  • Can be used to set initial values for object attributes
• Inheritance


  • The ability to inherit attributes and methods from one class to another
  • Subclass (child) - the class that inherits from another class
  • Superclass (parent) - the class being inherited from
• Inheritance


  • Useful for code reusability: reuse attributes and methods of an existing class when creating a new class
• Polymorphism


  The ability to perform a single action in different ways
• Encapsulation


  • Used to restrict access to methods and variables
  • Wraps code and data together within a single unit to prevent accidental modification
• Object Oriented

  In Java, everything is an Object. Java

  can be easily extended since it is based on the Object

  model.
• Platform Independent: Unlike many other programming

  languages including C and C++, when Java is compiled,

  it is not compiled into platform specific machine, rather

  into platform independent byte code. This byte code is

  distributed over the web and interpreted by the Virtual

  Machine (JVM) on whichever platform it is being run

  on.
• Simple: Java is designed to be easy to learn. If you

  understand the basic concept of OOP Java, it would be

  easy to master.
• Secure: With Java's secure feature it enables to develop

  virus-free, tamper-free systems. Authentication

  techniques are based on public-key encryption.
• Architecture-neutral: Java compiler generates an

  architecture-neutral object file format, which makes the

  compiled code executable on many processors, with the

  presence of Java runtime system.
• Portable: Being architecture-neutral and having no

  implementation dependent aspects of the specification

  makes Java portable. Compiler in Java is written in

  ANSI C with a clean portability boundary, which is a

  POSIX subset.