Syntax Overview

Let’s discuss some of the basic concepts we need to understand about the Java programming language.

Program Structure

To begin, let’s look at a simple Hello World program written in Java:

This program contains multiple important parts:

  1. Each Java program must contain at least one class, which is declared in a file that has the same name as the class. In this case, the class is HelloWorld, and it will be stored in a file called
  2. Class names, method names, and variable names in Java are case-sensitive. They are typically named using camel case, where classes are initially capitalized but methods and variables begin with a lowercase letter.
  3. The contents of a class should be directly after the class declaration, and are surrounded by curly braces {}.
  4. Each executable Java program must include at least one main() method. The method declaration of this main method should exactly match what is shown here. We’ll discuss these keywords in more detail in a later chapter.
  5. The code that will be executed when the main() method is called should directly follow the method declaration. As before, the contents of the method are surrounded by curly braces {}.
  6. Each statement, or line of code, in the program should be followed by a semicolon ;.
  7. To make the program readable, each block of code is typically indented within the curly braces that surround it.

Of course, this is a very brief overview for the Java programming language. To learn more, feel free to refer to the references listed below, as well as the textbook content for previous courses.


Try It!

See if you can use the code above to write your own Hello World program in the file that is open to the left. We’ll learn how to compile and run that program on the next page.