Introduction to Programming in Java
This page extends on the previous resource to delve deeper into Java itself, relating its use to its history.
5. "Hello World"
5.2. Inside the Magic
The "Hello World" program has become a de-facto standard with computer programmers for a first program in any language. The main advantage is that it is as simple as a program can get - when considering what it does. Depending upon the language and/or environment though, it may be necessary for some set-up code and/or syntactic glue.
In the program shown above, there are two pieces of syntactic glue.
The first part, public class HelloWorld, and the accompanying matched pair of curly braces, declare a Class construct. At this point, we could try and explain what a class is, but for someone who is genuinely new to programming, the explanation would probably be more of a distraction than a help. For now, we will settle for a simple universal truth - all Java code must be contained inside a Class construct.
The second part, public static void main(String args) and the accompanying matched pair of curly braces declare a Method construct. In particular, they declare a special type of method that Java can use as the entry point for a program. A method is a somewhat simpler construct than a class, but for now we will just describe it as a group of runnable code. A main method is required for each and every Java program. (Methods are also known as 'functions' in some other programming languages such as C++).