Java Syntax🌱 Beginner

Java has a strict, consistent structure. A few rules apply to every program — once they're second nature, the rest of the language follows.

Program structure

public class Main {                       // code lives in a class
    public static void main(String[] args) {  // execution starts here
        System.out.println("Hello, world!");   // a statement
    }
}

• All code lives inside a class; the file name must match the public class name (Main → Main.java).
• Execution starts at public static void main(String[] args).
• Every statement ends with a semicolon ;.
• Blocks are grouped with curly braces { }.
• Java is case-sensitive: Main and main are different.

Printing output

System.out.println("with a newline");
System.out.print("no newline");
System.out.printf("Name: %s, Age: %d%n", "Asha", 30);  // formatted

Comments

// single-line comment

/* multi-line
   comment */

/** Javadoc comment - documents a class or method */

Packages & imports

Classes are organised into packages. You import classes from other packages to use them.

package com.example.app;      // declares the package (first line)
import java.util.List;         // import a class to use it

Naming conventions