Identifiers in Java

What are Identifiers in Java?

• Allowed Characters: Identifiers can contain letters (A-Z, a-z), digits (0-9), underscores (_), and dollar signs ($).
• Starting Character: They must not begin with a digit.
• Case-Sensitivity: Java is case-sensitive, so `myVariable` and `MyVariable` are treated as two different identifiers.
• No Keywords: An identifier cannot be a reserved Java keyword (like `class`, `public`, `int`, etc.).
• Length: There is no official limit on the length of an identifier.

• Valid: userName, _my_data, $amount, User1
• Invalid: 1user (starts with a digit), user-name (contains a hyphen), public (is a keyword)

Following conventions makes code easier to read and maintain.

• Classes and Interfaces: Use PascalCase (upper camel case), starting with an uppercase letter. E.g., public class StudentRecord { ... }
• Variables and Methods: Use camelCase (lower camel case), starting with a lowercase letter. E.g., int studentAge;, void calculateScore() { ... }
• Constants: Use all uppercase letters, with words separated by underscores. E.g., static final int MAX_STUDENTS = 30;
• Packages: Use all lowercase letters. E.g., package com.example.project;