Java Is an Object-Oriented Language

This section provides a quick demonstration of the object-oriented programming nature of Java language.

Java is an object-oriented programming language.

What Is an Object? An object is a data instance of a user defined data type, which contains properties and methods.

What Is a Class? A class is a user defined data type which contains properties and methods.

Here is a sample Java program modified from Sun's "The Java Tutorials":

/**
 * ObjectDemo.java
 * Copyright (c) 2003 by Dr. Herong Yang
 */
class ObjectDemo {
   public static void main(String[] args) {

      // Creating 2 objects from the "Bicycle" class
      Bicycle bike1 = new Bicycle();
      Bicycle bike2 = new Bicycle();

      // Working with the first object
      bike1.changeCadence(50);
      bike1.speedUp(10);
      bike1.changeGear(2);
      bike1.printStates();

      // Working with the second object
      bike2.changeCadence(50);
      bike2.speedUp(10);
      bike2.changeGear(2);
      bike2.changeCadence(40);
      bike2.speedUp(10);
      bike2.changeGear(3);
      bike2.printStates();
   }

   // Defining a class
   private static class Bicycle {

      // Defining properties
      int cadence = 0;
      int speed = 0;
      int gear = 1;

      // Defining methods
      void changeCadence(int newValue) {
         cadence = newValue;
      }
      void changeGear(int newValue) {
         gear = newValue;
      }
      void speedUp(int increment) {
         speed = speed + increment;   
      }
      void applyBrakes(int decrement) {
         speed = speed - decrement;
      }
      void printStates() {
         System.out.println("Cadence: "+cadence);
         System.out.println("Speed: "+speed);
         System.out.println("Gear: "+gear);
      }
   }
}

If you run this Java sample program, you will get:

Cadence: 50
Speed: 10
Gear: 2
Cadence: 40
Speed: 20
Gear: 3

Table of Contents

 About This Book

 1957 - FORTRAN Language Developed by IBM

 1970 - UNIX Operating System Developed by AT&T Bell Labs

 1971 - FTP Protocol Created by Abhay Bhushan

 1972 - C Language Developed by Dennis Ritchie

 1976 - vi Text Editor Developed by Bill Joy

 1977 - Apple II Designed by Steve Jobs and Steve Wozniak

 1977 - The Bourne Shell Developed by Stephen Bourne

 1978 - The C Shell Developed by Bill Joy

 1978 - Bash (Bourne-Again Shell) Developed by Brian Fox

 1979 - The Tcsh (TENEX C Shell) Developed by Ken Greer

 1983 - "Sendmail" Mail Transfer Agent Developed by Eric Allman

 1984 - Macintosh Developed by Apple Inc.

 1984 - X Window System Developed a MIT Team

 1991 - WWW (World Wide Web) Developed by Tim Berners-Lee

 1991 - Gopher Protocol Created by a University of Minnesota Team

1995 - Java Language Developed by Sun Microsystems

 What Is Java Language?

 Java Compilation and Execution Processes

 Java Is Platform Independent

Java Is an Object-Oriented Language

 Java Supports Automatic Garbage Collection

 Java Supports Multi-Threading Programming

 1995 - PHP: Hypertext Preprocessor Created by Rasmus Lerdorf

 2002 - .NET Framework Developed by Microsoft

 References

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