//***********************************************************************//
// //
// - "Talk to me like I'm a 3 year old!" Programming Lessons - //
// //
// $Author: Ben Humphrey digiben@gametutorials.com //
// //
// $Program: FirstJavaApp //
// //
// $Description: Displays "Hello World!" to the screen //
// //
//***********************************************************************//
// What you are reading right now is what are called "comments". Comments
// allow you to write descriptions and explanations of your code, but are
// ignored by the compiler. The compiler is what actually takes all of our
// code and converts it into a library or program that you can run, like a
// ".exe" file. If you haven't already, please review the Beginner FAQ which
// explains basic programming vocabulary so you won't be lost when reading
// the tutorials. There is a big section for using Java so it's important
// that you read it. The FAQ will answer many questions about using Java.
// You can find it on the CD or at the below address:
//
// http://www.GameTutorials.com/beginnerfaq.htm
//
// To create comments in code you just use the "//" characters. Notice that
// the text turns green by default, which lets you know that the compiler
// will ignore the text. The "//" comments only create comments for one
// line of text, where as the using the "/* */" characters comment multiple
// lines. Look below for an example:
/*
This is an example of commenting multiple lines without using the "//"
characters. Do you see how this text is green?
*/
//
// Below we will show the source code for your first Java application. You
// can read our comments next to the code to learn what each line of code
// does, and then apply those concepts to create your own programs. After
// each tutorial we encourage you to create your own project from scratch
// and test the skills you learned to make sure you understand the concepts.
//
// Right before we jump into the code let's go over what is going on with
// this program. When we run this program we will see the output in the
// "Output" window of NetBeans. The output will say "Hello World!". This will
// demonstrate how to print text using java, the easiest first program.
// Below is the actual code for our first Java application:
public class Main
{
public static void main(String[] args)
{
System.out.println("Hello World!");
}
}
///////////////////////////////////////////////////////////////////////////////
//
// * Quick Notes *
//
// That's all the code required to run your first Java application. To run this
// program you will want to use the menu: "Run->Run Main Project"
// You can also just use the quicker shortcut: F6
// To just build the project and check for possible errors, use: F11
//
// Be sure to watch the step-by-step video tutorial that shows how to create
// a Java application. Basically, you want to go: "File->New Project...",
// then choose "Java Application" in the "General" folder. Next, just name
// the project and click OK. Now you have a project with a new file to start
// coding in. In order to just show the smallest amount of code possible to
// print text to the screen I got rid of a few lines of code from the default
// "Java Application" project that was created by NetBeans.
//
// We didn't stick comments in the code above so that you could see the code
// all by itself. Keep in mind that all the code in Java is case sensitive, which
// means you must use upper- and lower-case characters where appropriate. For
// example, "public class Main" and "Public Class main" is totally different code.
// Now let's go through each line and explain what it does.
/*
// This line below defines our class. Since the older languages like C and Pascal,
// Object-Oriented Programming (OOP) has become the new technique in programming.
// Instead of having tons of functions floating around wherever they want, we
// now include them in what we call a class (also called an "object"). In short,
// this gives us many benefits, namely better code organization and readability.
// As you go through the rest of the tutorials you will see some more advanced
// benefits to classes, but for now just think of them as ways to organize your code.
// Notice that we use the keywords "public class" in front, with our class name afterwards.
// The class name has the be the same name as the first part of the java file, "Main.java".
// This says that we are creating a class called "Main". The "public" keyword says
// that the class is public, which means that any other class can use it.
public class Main
// This next line is a curly bracket and tells us that we are starting a new "scope"
// for our class. The starting of a scope is a '{' character, with the end being a '}'.
// Think of this as being a beginning and an end statement. Whenever you create a new
// scope you want to indent the next code with the tab key. This gives us clean code,
// but will still compile and run fine if you don't tab in. You could have the whole
// program on one line and it would still compile and run fine, but would make people
// want to vomit on your keyboard when they saw it :)
{
// This next line actually starts our main() function for our program. That means
// that when our program starts this is the first function called. The "static"
// keyword is mandatory and says that the main() function will stay in memory until
// the program closes. The "void" keyword tells us that this function won't return
// any data, it will just run and quit. Some functions, like the square root function
// on your calculator, will return a number right? Well, our main() doesn't need to.
// The "main" must be spelled exactly like that, with a lower-case 'm'. The "()"
// characters let us know that this is a function. The "public" keyword makes the
// main() function public so any other function or class can call it. In between
// the parenthesis we declare a variable of type "String", which hold any special
// arguments that are passed into the program. The "[]" characters mean that the
// variable name "args" is an array of type "String" (or a list of Strings). We
// will go over variables, strings and arrays in later tutorials. Don't worry
// about this line, because later we will be explain more of these concepts.
public static void main(String[] args)
// Now we want to start a new scope for the main() function so we use a curly bracket.
{
// This is the line that prints out the text to the screen. Notice that we need
// to use the "System.out" class (or object) to access the println() function.
// You can store functions in classes, and you just need to type a '.' character
// after an object to start using its functions. In NetBeans you will notice
// that once you type in the period character a bunch of functions and class
// variables will pop up. This is called "IntelliSense", which helps you to easily
// select functions or variables stored in the class. You can choose to ignore
// this and keep typing whatever you want.
//
// So, we call println(), which takes a string of characters (also called a
// char string) to print out to the screen. You must use the '"' characters to
// surround the string that you want to "pass into" the println() function.
// For example, this would error and not compile: System.out.println(Hello World!);
// Notice that we pass the string in between the open and closed parenthesis. To
// end the line of code we put a semicolen after the last parenthesis. Since you
// can have many lines of code on one line, the ';' tells the compiler to process
// the previous code before going on to the next code; stating that the previous
// code and the next code are not connected.
System.out.println("Hello World!");
// This line ends the scope of the main() function. Notice how it lines up with
// the start of the scope. This is how you line up scopes so it's easy to read.
}
// This ends the scope for the entire "Main" class. See how it lines up with
// the first open curly backet. This is what good, clean code looks like.
}
*/
// That's all there is to writing a basic java application. There were probably
// a lot of things that you might not still understand fully, but you should be at least
// able to create a program that prints text out to the screen. The greater understanding
// will come later as you see more examples and explanations of the concepts used in the
// next tutorials.
//
// What about if you want to print out many lines of text? Good question, just call the
// println() function as many times as you need like this:
/*
System.out.println("Hello World!");
System.out.println("Hello World Again!");
*/
// Of course, you would put that code in between your main() function's scope (curly brackets).
// After practicing your new skills please move on to the next tutorial that discusses
// "Keyboard Input".
//
//
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