Java Syntax

Java is precise. Every program has the same skeleton.

The minimum Java program

Every executable Java file has at least:

• One class declaration (the file Hello.java contains class Hello)
• One main method — the entry point
• Curly braces { } defining code blocks
• Semicolons ; ending each statement

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

Breaking it down

public class Hello — declares a class named Hello. The keyword public means anyone can use this class. The filename must match: Hello.java.

public static void main(String[] args) — the main method, where execution begins:

• public — accessible from anywhere
• static — belongs to the class, not an instance (you don't need to create a Hello object to call it)
• void — returns nothing
• String[] args — receives command-line arguments as an array of strings

System.out.println(...) — prints a line to the console.

Statements and blocks

A statement is one instruction. Java statements end with a semicolon:

int age = 28;
String name = "Raman";
System.out.println(name);

A block groups statements with curly braces. Methods, loops, classes — all use blocks.

Comments

Java has three comment styles:

// Single-line comment

/* Multi-line
   comment block */

/**
 * Documentation comment (Javadoc).
 * @param args command-line arguments
 */

Case sensitivity

Java is strictly case-sensitive. Name, name, and NAME are three different identifiers. main works; Main doesn't.

Naming conventions

• Classes: PascalCase — Customer, OrderProcessor
• Methods, variables: camelCase — getName, totalPrice
• Constants: UPPER_SNAKE_CASE — MAX_RETRIES, PI
• Packages: lowercase — com.codewithraman.utils