Java Naming Conventions

Every Indian railway station has a short code: NDLS, CSMT, MAS. Nothing stops a station from being called something else, but because everyone follows the same pattern, you can read a ticket instantly. Java names work the same way. The compiler accepts almost anything, but every Java team follows the same naming conventions, so you can tell at a glance whether a name is a class, a method, a variable or a constant.

The Conventions at a Glance

The Conventions in Code

public class TicketBooking {
    static final int MAX_SEATS = 72;
 
    static int calculateFare(int farePerPerson, int passengerCount) {
        return farePerPerson * passengerCount;
    }
 
    public static void main(String[] args) {
        int passengerCount = 4;
        int fare = calculateFare(450, passengerCount);
        System.out.println("Seats in coach: " + MAX_SEATS);
        System.out.println("Fare for " + passengerCount + ": Rs. " + fare);
    }
}

Seats in coach: 72
Fare for 4: Rs. 1800

How it works

1. Line 1: TicketBooking is a class, so it's PascalCase.
2. Line 2: MAX_SEATS never changes, so it's a constant in UPPER_SNAKE_CASE.
3. Line 4: calculateFare is a method that does something, so it's a verb in camelCase. Its parameters are camelCase nouns.
4. Lines 9 to 12 use the names; you can tell each kind apart without looking at its declaration.

Try it yourself: rename calculateFare to CalculateFare everywhere. It still compiles. Why would a teammate still ask you to change it back?

Good Names, Not Just Correct Ones

Following the style is the first step. A name also has to say what the thing is:

Short names like i and j are fine for loop counters, where everyone knows what they mean.

Common Mistakes

Using underscores in variable names. passenger_count is Python style. In Java, write passengerCount; underscores are only for constants.

Lowercase class names. class ticket compiles, but every Java developer reads ticket as a variable, which makes code confusing.

Abbreviating everything. calcTktFr() saves a few letters and costs every reader time. Modern IDEs complete long names for you.

Practice

1. Easy: Fix the style of these names: class bank_account, int Balance, void Deposit(), final static double gstrate, package Com.PoolString.Billing.
2. Harder: Write a class for a library book with a constant for the late fee per day, a method that works out the fine, and variables for the number of late days. Use the conventions from this lesson.

Key Takeaways