OOP_1

• OOP


  Object Oriented Programming
• Object Oriented Programming


  • Methodology or paradigm to design a program using classes and objects
  • Simplifies software development and maintenance
• Object


  Any real-world entity such as a pen, chair, table, computer, watch, etc. that has state and behavior
• Object-Oriented Programming


  • Languages that uses objects in programming
  • Aims to implement real-world entities like inheritance, hiding, polymorphism in programming
• Class


  • A blueprint from which you can create an individual object
  • A logical entity that does not consume any space
• OOP Concepts


  • Inheritance
  • Polymorphism
  • Abstraction
  • Encapsulation
• Java


  • One of the most popular and widely used programming language and platform
  • Fast, reliable and secure
• Java was created


  1991
• Oak


  Initial name of Java
• James Gosling


  Development leader in Sun's microsystem
• First project developed using Java

  1995
• Characteristics of Java


  • Object-oriented model
  • Simple
  • Platform independent
  • Robust
  • Strong security
  • Portable language
  • Supports multi-threading
  • High performance
• JRE


  The on-disk part of Java that creates the JVM
• JDK


  Allows developers to create Java programs that can be executed and run by the JVM and JRE
• JVM


  The Java platform component that executes programs
• Java Source File Structure

  • Each Java source file must have the same name as a public class that it declares
  • Each Java source file can contain only one public class declaration
  • The file extension must be .java
  • The filename is case-sensitive
• Phases of a Java Program

  1. Write the program

  2. Compile the program

  3. Run the program
• Compilation in Java


  • Java programs are compiled into bytecode, which the JVM (Java Virtual Machine) then executes at runtime
  • Java source code is compiled into bytecode which gets saved on the disk with the file extension .class
  • When the program is to be run, the bytecode is converted, using the just-in-time (JIT) compiler, into machine code which is then executed