Java Naming Conventions: PascalCase, camelCase, and more

In programming, the way we name our variables, functions, and classes is crucial for the readability and maintainability of the code. Different casings are used as a naming convention in different programming languages or even within different parts of the same codebase. Here are some of the most common ones:

PascalCase (Upper Camel Case):

In PascalCase, each word in the identifier is capitalized, including the first one. It’s often used in programming languages for naming classes, records, and other user-defined types. For example, CustomerService, UserProfile, and AudioSystem.

camelCase (Lower Camel Case):

camelCase is similar to PascalCase, but the first letter of the first word is in lowercase. It’s commonly used for naming variables and functions. This style is prevalent in JavaScript, Java, and other programming languages. Examples include customerService, userProfile, and audioSystem.

Kebab-case (dash-case or hyphen-case):

Kebab-case involves writing all words in lowercase and separating them with hyphens. It’s not typically used in programming languages because it’s not compatible with variable names in many languages. However, it’s quite popular in URLs, file names, and CSS class names. For instance, customer-service, user-profile, and audio-system.

Snake_case:

In snake_case, words are written in lowercase and separated by underscores. It’s frequently used in languages like Python, especially for variables and function names. Examples include customer_service, user_profile, and audio_system.

Each coding community and language tends to have its preferences and style guides that dictate when and where to use each of these casings. Adhering to these conventions makes your code more readable and easier to maintain.

In Java, different casing conventions are used to distinguish between variables, methods, constants, and classes. Let’s explore each with examples:

PascalCase (Upper Camel Case)

PascalCase is primarily used for naming classes and interfaces in Java.

public class CustomerAccount {
    // Class names are in PascalCase
}

interface Drawable {
    // Interface names are also in PascalCase
}

camelCase (Lower Camel Case)

camelCase is used for naming variables and methods. The first letter is lowercase, and each subsequent starting word is capitalized.

public class User {
    private String userName;  // Variable names in camelCase
    private String password;

    public void setPassword(String password) {  // Method names in camelCase
        this.password = password;
    }
    
    public String getPassword() {
        return this.password;
    }
}

UPPER_SNAKE_CASE

UPPER_SNAKE_CASE is conventionally used for constants in Java, where all letters are uppercase, and words are separated by underscores.

public class Constants {
    public static final int MAX_USERS = 50;  // Constant names in UPPER_SNAKE_CASE
    public static final String DB_NAME = "UserDB";
}

snake_case

snake_case isn’t commonly used in standard Java programming conventions, but you might encounter it in specific contexts (like when interacting with databases or systems that prefer this convention).

public class DatabaseRecord {
    private String record_id;  // Not typically used in Java for variable names
    private String user_name;
}

Note that while you can technically use snake_case in Java, it’s not the standard practice, and it’s generally recommended to stick to camelCase for variables and methods, PascalCase for classes and interfaces, and UPPER_SNAKE_CASE for constants to maintain consistency and readability in your code.