Java Syntax Basics

You now know about classes, the main() method, statements, and code blocks. Now let's summarize a few basic syntax rules that apply to every Java program.

System.out.println("Hello!"); // correct
system.out.println("Hello!"); // Error! Java is case-sensitive

This applies to everything in Java: class names, method names, keywords like "class" or "public". A single letter with the wrong capitalization leads to a compiler error.

Another fixed rule: the name of the Java file must exactly match the name of the public class inside it, including capitalization, plus the ".java" extension.

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, Java!");
    }
}

Java is case-sensitive (for example, "Main" and "main" are different).

Indentation — meaning spaces at the start of a line that visually shift nested blocks inward — is, on the other hand, not necessary for the compiler. Java compiles code without any indentation just fine. Still, you should always indent cleanly, because it makes your code much easier for people to read.

public class Main {
public static void main(String[] args) {
System.out.println("Hello, Java!");
}
}

Which statement about indentation in Java is correct?

In summary, every Java program follows these rules: the code lives in a class, execution starts in the main() method, every statement ends with a semicolon, related statements sit in a block of curly braces, Java is case-sensitive, and the file name must match the public class.

A file containing the class "public class Main" must be named ____.