1 · Foundations · lesson 2 of 41

Hello, World

Your first program — and every piece of the required ceremony explained.

Every Java program starts inside a class, and execution begins at a method named main with a very specific signature.

Java
public class Hello {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}
  • ▸public — visible to the JVM launcher outside this class.
  • ▸class Hello — the container; filename must be Hello.java.
  • ▸static — no instance is needed to call main.
  • ▸void — main returns nothing.
  • ▸String[] args — command-line arguments.
NOTE
System.out is a PrintStream; println writes a line to standard output.
Key takeaways
  • ✓Filename must match the public class name.
  • ✓main has a fixed signature: public static void main(String[]).
  • ✓Statements end with a semicolon; blocks use braces.
← Back to Java playground