📝 What You’ll Learn

• Java program structure
• Key syntax elements: classes, methods, statements
• Naming conventions
• How Java code is organized and executed

🧱 Basic Java Structure

Every Java application is made up of classes and methods. The main method is the entry point of any standalone Java program.

Here’s a minimal Java program:

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

🔍 Breakdown

• public class HelloWorld: Defines a class named HelloWorld. Java programs are class-based.
• public static void main(String[] args): The starting point of the program.
• System.out.println(): A statement that prints to the console.
• {}: Code blocks grouped together.
• ;: Every statement ends with a semicolon.

🧭 Java is Case-Sensitive

These are not the same:

System.out.println();    // valid
system.out.println();    // invalid – “system” should be capitalized

🧠 Naming Conventions

Follow these standard conventions to keep code readable:

| Type | Convention | Example | |-||--| | Class | PascalCase | MyFirstClass | | Method/Variable| camelCase | printMessage() | | Constant | ALL_CAPS_WITH_UNDERSCORES | MAX_VALUE |

✅ Code Formatting Tips

• Use indentation (typically 4 spaces or a tab).
• Keep braces on the same or next line (consistent with your IDE settings).
• Add comments using:
  • // for single line
  • /* */ for multi-line

// This is a single-line comment

/*
 This is a
 multi-line comment
*/

💡 Example: Simple Java Program

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

🚫 Common Syntax Errors

• Missing semicolon ;
• Unmatched braces {} or parentheses ()
• Wrong casing (e.g., String vs string)
• Incorrect method or class names

📘 Recap

Java code follows a consistent structure:

• Classes contain methods
• The main() method is the starting point
• Every statement ends in ;
• Curly braces define code blocks