Java Syntax and Basic Structure

- July 18, 2025

Chapter 3: Java Syntax and Basic Structure

3.1 Structure of a Java Program

Every Java program follows a specific structure that ensures it runs correctly. It includes:

Class definition
main() method (entry point)
Statements inside curly braces { }

public class MyProgram {
    public static void main(String[] args) {
        System.out.println("Java is powerful!");
    }
}

3.2 Components of a Java Program

Class Name
Methods
Statements & Expressions

3.3 Java Syntax Rules

Java is case-sensitive: Main ≠ main
File name must match the public class name
The main method must be exactly: public static void main(String[] args)

3.4 Java Comments

Comments make your code easy to understand:

Single-line: // This is a single-line comment
Multi-line:
```
/* This is a
   multi-line comment */
```

Documentation comment:

/**
 * This class prints Hello World.
 */

3.5 Printing Output in Java

We use System.out.println() or System.out.print():

System.out.println("Welcome!");
System.out.print("Hello ");
System.out.print("Java");

Output:

Welcome!
Hello Java

println prints and moves to a new line, while print stays on the same line.

3.6 The main() Method Breakdown

public static void main(String[] args)

This is the entry point for any Java application.

3.7 Writing Clean Java Code

Use meaningful class and variable names
Follow proper indentation and spacing
Write comments to explain your logic

💻 Practice Programs

Print your school or college name.
Modify HelloWorld to print your name and city.
Add single-line and multi-line comments in your code.
Create a class Intro that prints 3 lines of output.

❓ FAQs on Java Syntax & Structure

Q1: What is the basic structure of a Java program?

A: It includes:

Class definition
Main method
Statements inside the method

Q2: What is the role of the main() method?

A: It’s the entry point where Java program execution begins. Signature:

public static void main(String[] args)

Q3: What are Java statements and blocks?

A: Statements are executable instructions. A block is a group of statements enclosed in curly braces { }.

Q4: Are semicolons important in Java?

A: Yes. Each Java statement must end with a semicolon ;.

Q5: What is case sensitivity in Java?

A: Java treats identifiers with different letter cases as different entities.

Q6: How are comments written in Java?

Single-line: // comment
Multi-line:
```
/* comment */
```

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