In our daily life, everything has a name. Your name identifies you in school, your roll number identifies you in class and even your phone number identifies you among millions of users. Without names or identifiers, it would be impossible to recognize or distinguish things.
In the same way, when we write programs in Java, we need names for variables, methods, classes and objects. These names are called identifiers.
Identifiers
An identifier in Java is the name given to elements such as variables, methods, classes, packages or interfaces. Identifiers are names you use to identify different parts of your program.
Purpose of Identifiers
- To uniquely identify variables, classes, methods and objects.
- To make programs readable and meaningful.
- To help Java recognize which part of the code is being referred to.
Rules for Defining Java Identifiers
Java has some rules you must follow while naming identifiers:
- Identifiers can contain letters (A–Z, a–z), digits (0–9), underscore (_), and dollar sign ($).
- They cannot start with a digit (❌ 1name, ✅ name1).
- They cannot use reserved keywords (❌ class, int).
- Identifiers are case-sensitive (Student and student are different).
- No special symbols are allowed except _ and $.
Valid and Invalid Identifiers
Identifier | Valid / Invalid | Reason |
| studentName | ✅ Valid | Uses letters only, follows camelCase |
roll_no | ✅ Valid | Underscore allowed |
$salary | ✅ Valid | Dollar sign allowed |
_age | ✅ Valid | Underscore at start allowed |
student1 | ✅ Valid | Can contain digits (but not at start) |
123name | ❌ Invalid | Cannot start with a digit |
student-name | ❌ Invalid | Hyphen – not allowed |
my name | ❌ Invalid | Spaces not allowed |
class | ❌ Invalid | Reserved keyword in Java |
total@marks | ❌ Invalid | @ symbol not allowed |
How Java Identifiers Work
When you create a variable like:
int age = 15;Here, age is the identifier.
Java uses this name to store and retrieve data from memory. Every identifier works like a label for data or code.
Best Practices for Naming Identifiers in Java
- Use Meaningful Names
- Start with a Letter
- Avoid Using Single Characters
- Avoid Abbreviations and Acronyms
- Differentiate Clearly
- Context Matters
- Avoid Redundancy
Final Thought on Identifiers
Identifiers in Java are just like names in real life . They help us easily recognize and use things. By following simple rules and best practices, you can make your programs clear, professional and error-free.
If you’re thinking of learning program
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