Java tutorial Part 4

import java.io.*;

class example

{  

  public static void main(String args[])

  {  

       System.out.println("Hello Java");  

   }  

}  

Let's look at how to save the file, compile and run the program. Please follow the steps given below:

 Open notepad and add the code as above.

 Save the file as: example.java.

 Open a command prompt window and go o the directory where you saved the class. Assume it's C:\.

 Set the path

 Type ' javac example.java ' and press enter to compile your code. If there are no errors in your code, the command prompt will take you to the next line (Assumption : The path variable is set).

 Now, type ' java example ' to run your program.

 You will be able to see ' Hello Java ' printed on the window.

 Understanding first java program
Let's see what is the meaning of class, public, static, void, main, String[], System.out.println().

class keyword is used to declare a class in java.

public keyword is an access modifier which represents visibility, it means it is visible to all.

static is a keyword, if we declare any method as static, it is known as static method. The core 
advantage of static method is that there is no need to create object to invoke the static method. The 
main method is executed by the JVM, so it doesn't require to create object to invoke the main method. 
So it saves memory.
void is the return type of the method, it means it doesn't return any value.

main represents startup of the program.

String[] args is used for command line argument. We will learn it later.

System.out.println() is used print statement. We will learn about the internal working of 

System.out.println statement later.