Java Basics

When we consider a Java program it can be defined as a collection of objects that communicate via invoking each other's methods. Let us now briefly look into what do class, object, methods and instance variables mean.

• Object - Objects have states and behaviors. Example: A dog has states - color, name, breed as well as behaviors -wagging, barking, eating. An object is an instance of a class.
• Class - A class can be defined as a template/ blue print that describes the behaviors/states that object of its type support.
• Methods - A method is basically a behavior. A class can contain many methods. It is in methods where the logics are written, data is manipulated and all the actions are executed.
• Instance Variables - Each object has its unique set of instance variables. An object's state is created by the values assigned to these instance variables.

First Java Program:

            public class MyFirstJavaProgram  

            {  
             /* This is my first java program.  
             * This will print 'Hello World' as the output
             */
                public static void main(String []args)

                {
                   System.out.println("Hello World"); // prints Hello World
                }
            }