? Java Identifiers Rules

? Quick Overview

In Java, identifiers are the names given to variables, methods, classes, interfaces, and packages. Java follows strict rules while naming identifiers to ensure clarity, consistency, and compiler compatibility.

? Key Concepts

• Identifiers are used to name program elements
• They are case-sensitive
• Must follow Java language rules
• Cannot clash with Java reserved keywords

? Syntax / Theory

• Must begin with a letter (A–Z or a–z), underscore (_) or dollar sign ($)
• Cannot start with a digit
• Can contain letters, digits, underscores, and dollar signs
• No spaces allowed
• Java keywords cannot be used as identifiers

// Valid Java identifiers
int age;
String studentName;
double total_marks;
int $count;

// Invalid Java identifiers (will cause compile-time errors)
int 1number;
int class;
int total marks;