HelloWorld is usually the first program you write in a new language, or if you are testing a new programming platform.  
  It is a very simple program in that it really only consists of the main method itself, with a call to System.out.println (String).  
  Since it is an introductory program, we'll go through the different statements in the code:
  First, there are comments at the top:

        //:::::::::::::::::::::::::::::::::::::::::::::::::::::::
        /** @author   Casey Bowman
         *  @version  1.1
         *  @date     Fri Feb 27 12:00:00 EST 2015
         *  @see      LICENSE (MIT style license file).
         */

  There is a line with a double forward slash followed by a long line of colons.  
  A double slash informs the compiler that whatever comes after the double slash, ON THE SAME LINE, is a comment.  
  You will notice that the next line begins with a forward slash and two stars.  
  The second star is stylistic, but the "/*" informs the compiler that anything that comes after it is a comment, 
    regardless of whether you have switched to another line.  
  The stars at the beginning of the next three lines are stylistic, and are there to provide a visual block space 
    for the comments.  
  A multi-line comment is ended by putting a "*/" at the end of your comment block.

  The comment block itself informs anyone looking at the code of the author(s) name(s), the version number, 
    when the code was started, and what kind of software license is attached to the code.  
  The Hello World program is probably not subject to licenses, but it's a good idea to put a license on all of your code.  
  Once you start writing important or complex code, an appropriate software license will protect you from having your 
    ideas used in any way that is against your wishes.  
  The MIT license is a very open license as it basically allows anyone to reuse the code in any way that they want.


  The next statement in the java file is actual code:

        public class HelloWorld
        {

  This code block sets up that we will be creating a class called HelloWorld.  
  In Java, the class name must match the file name.  
  The curly brace is important as it announces that the next lines will be code for the HelloWorld class.

  the next statement is another comment:

        //:::::::::::::::::::::::::::::::::::::::::::::::::::
        // Main method

  This comment includes another line of colons.  
  This kind of comment line serves as another visual boundary to make it easier to spot comments and easier to read them.  
  The second line is a comment informing us that the next block of code will define the main method of the program.

  We finally get to the heart of the code, which in this case is the main method.  
  Often, the main method only begins execution, but in this case, the main method is all we have:

        public static void main (String[] args) 
        {
            System.out.println ("Hello World!");
        } // main

  We'll go through this code line-by-line and word-by-word.  First, the method definition:
		
        public static void main (String[] args) 
        {

  The first word states that the method will be public (main must always be public), meaning it can be accessed 
    outside of this program.  
  Which is essential if we want the Java Virtual Machine to be able to run our program!  
  The next word states that the method will be static, which means that the method will belong to the class, and not 
    to an object created from the class.  
  This distinction will get more clear with more experience.  
  The next word states that the method will not have a return type.  
  Quite often there is no need to have main return anything, and so it is made a void method.  
  The word main is the name of the method, and in this case, the name main is what the JVM will look for when 
    trying to execute your program.  
  It is important to note that Java classes do not need a main.  
  Java PROGRAMS need a main somewhere, but programs can be made up of many individual classes.  
  The parenthetical statement informs the compiler that the main method will take a String array as a parameter.  
  This String array is the collection of strings commonly referred to as "command line arguments".  
  The final curly brace informs the compiler that the following lines will define what the main method does.

  The next two lines:

        System.out.println ("Hello World!");
        } // main

  The first line here is a call to a method that allows us to print a String to the command terminal.  
  This method is called "println".  The preceding two words tell the compiler and JVM where to find it.  
  First, we must understand that println is simply a method inside the PrintStream class.  
  So any PrintStream object will have a println method in it.  
  In this case, the word "out" is a reference to a PrintStream object.  
  All PrintStream objects must have a location declared that tells the method println where to print.  
  This specific PrintStream object has been told by the "System" class to send Strings to the command terminal 
    using the println method.  
  The parenthetical part of the line declares that the String to be output to the terminal should be "Hello World!".  
  The semi-colon ends the execution statement and is required.  
  The final curly brace "closes the the main method, meaning everything between the first curly brace (in the method) 
    and this one has defined the main method.  
  Anything outside these curly braces are not associated with main.  
  The comment informs a reader that this curly brace has ended the main method.

  The final line of the program is:

        } // HelloWorld

  The curly brace closes the class, and the comment informs a reader that the class has been closed by the curly brace.