What is Java Syntax?

Java syntax is a set of rules that defines how Java programs should be written and structured.

Basic Structure of Java Program

A simple Java program looks like this:

public class Main {

    public static void main(String[] args) {

        System.out.println("Hello Java");

    }

}

Let us understand each part of this program.

Class Declaration

public class Main

• public → Access modifier
• class → Keyword used to create class
• Main → Class name

Main Method

public static void main(String[] args)

The main() method is the starting point of every Java application.

• public → Accessible from anywhere
• static → Method belongs to class
• void → No return value
• main() → Main method name
• String[] args → Command line arguments

Printing Output

Java uses System.out.println() to print output on the screen.

System.out.println("Welcome to Java");

Output

Welcome to Java

Semicolon in Java

Every statement in Java must end with a semicolon (;).

int a = 10;
System.out.println(a);

Java is Case Sensitive

Java treats uppercase and lowercase letters differently.

System.out.println("Correct");

system.out.println("Wrong");

In Java:

• System is correct
• system is incorrect

Comments in Java

Comments are used to explain code. Comments are ignored by the compiler.

Single Line Comment

// This is single line comment

Multi Line Comment

/*
This is
multi line comment
*/

Variables in Java

Variables are used to store data.

int age = 25;

String name = "John";

double salary = 45000.50;

Rules for Variable Names

• Variable names should start with letter
• Cannot start with number
• No spaces allowed
• Use meaningful names

Curly Braces { }

Curly braces define blocks of code in Java.

if(true) {

    System.out.println("Java");

}

Indentation

Indentation improves readability of code. Although Java compiler ignores spaces, proper indentation makes code easier to understand.

public class Test {

    public static void main(String[] args) {

        System.out.println("Good Formatting");

    }

}

Java Keywords

Keywords are reserved words in Java. They have predefined meanings.

Complete Java Example

public class Student {

    public static void main(String[] args) {

        String name = "Alex";

        int age = 20;

        System.out.println(name);

        System.out.println(age);

    }

}

Output

Alex
20

Common Syntax Errors

• Missing semicolon
• Incorrect brackets
• Wrong spelling of keywords
• Using undeclared variables
• Case sensitivity mistakes

Conclusion

Understanding Java syntax is the first step toward becoming a Java developer. Once you learn syntax properly, writing Java programs becomes much easier.