Java Syntax

Java Syntax (Beginner-Friendly Guide)

Once Java is installed and ready, the next step is understanding the syntax — the rules for writing Java code correctly.

Basic Java Program Structure

Breakdown:

Part	Meaning
`class Main`	Defines a class named Main
`{ }`	Curly braces define the body of the class or method
`public static void main(String[] args)`	Entry point of every Java program
`System.out.println()`	Prints output to the console

Java is Case Sensitive

Examples:

Correct	Incorrect
`System.out.println()`	`system.out.println()`
`main`	`Main` (won’t run)
`class`	`Class`

Statements and Semicolons

Every executable statement ends with a semicolon (;).

Example:

Comments in Java

Comments are ignored by the compiler.

Single-line Comment

Multi-line Comment

Documentation Comment (For APIs)

Java Naming Rules

Rule	Example
Class name starts with Capital letter	`class Student { }`
Method and variable names start with lowercase	`int age; void display()`
CamelCase convention	`studentName, totalAmount`

Invalid:

 int 1count;
 class public; (keyword not allowed)

1 2	int 1count; class public; (keyword not allowed)

Valid:

int count1;
int _value;

1 2	int count1; int _value;

Java Print Statements

Example:

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

1 2	System.out.print("Hello "); System.out.print("Java");

Output:

Variables and Data Types Example

Syntax Errors vs. Runtime Errors

Type	Meaning	Example
Syntax Error	Code written incorrectly	Missing semicolon
Runtime Error	Error while program runs	Divide by zero
Logic Error	Wrong output	Incorrect formula

Example Program with Variables & Comments

Key Points to Remember

Java code must be inside a class.
Program execution always starts from main() method.
Statements end with ;
Java uses {} to group code blocks.
Follow camelCase naming rules.