OOPS THROUGH JAVA

Java is “Object Oriented Programming Language” unlike ‘C language’ which is a structured oriented one.

Java Language starts with packages. Within Packages are classes, within classes are methods, constants and  variables.  In java, source code (.java files) is compiled, it gets transated into byte codes and then placed into ‘.class’.

OOPS concepts: There are 4 principles of object oriented programming.

They are: Abstraction, Encapsulation, Inheritance and Polymorphism.

• Abstraction: Here in Abstraction, object of the program is defined.
• Encapsulation: Encapsulation allows the user to access data by providing a interface.
• Inheritance: Here in Inheritance, one object acquires the properties of another object.
• Polymorphism: Polymorphism , as the name suggests is having multiple forms of classes and methods for various implementations.

Features of Java:  There are some powerful features of Java.

• Simple
• Reusability of code
• Robust
• Secure
• High Performance
• Dynamic
• Threaded
• Distributed
• Multi threaded

Software Requirements of Java:  JDK and JRE 1.5

Architecture of Java: After a Java programs is written, compiler reads the statements in the programme and translates into machine format called byte code. And then the compiled Java code which is the resulting byte code will be executed at runtime.  Java programs are written and executed in two ways:

1. By ‘A Java Swing Application’—which is a Stand-alone application
2. By Applet which runs on a web browser like internet explorer.

Java Source Code:  A Java is a collection of one or more collection of java classes. A java source file can contain many classes which can be executed at any time within a class.

A simple Java program :

public class ( HelloWorld    {

public static void main String args[]  {

system.out.println(“HelloWorld”)  ;

} //  End of main

} // End of HelloWorld Class

Output: HelloWorld

Applications of Java:

• Embedded Systems
• Web Applications
• Mobile Applications
• GUI Applications