Difference Between Final, Finally and Finalize

This is one of the most common Java interview questions, mainly because the three words look alike. In fact they have nothing to do with each other: final is a keyword that stops things from changing, finally is a block that always runs after a try, and finalize() is an old cleanup method that is now deprecated. One short program shows all three.

All Three in One Program

public class ThreeWords {
    static final double GST_RATE = 0.18;
 
    public static void main(String[] args) {
        final String customer = "Navika";
        try {
            double bill = 1000 * (1 + GST_RATE);
            System.out.println(customer + " pays Rs. " + bill);
        } finally {
            System.out.println("Receipt closed");
        }
    }
}

Navika pays Rs. 1180.0
Receipt closed

How it works

1. final makes GST_RATE a constant and customer a variable that can't be reassigned.
2. finally prints "Receipt closed" after the try, as it would even if the try had thrown.
3. finalize() doesn't appear, and shouldn't: it's deprecated for removal (see "Java Finalize Method (Deprecated)").

Side by Side

What final Does in Each Place

Common Mistakes

Saying finally is a keyword like final. It is a keyword, but it introduces a block; it's not a modifier.

Recommending finalize() for cleanup. It's unreliable and deprecated; use try-with-resources.

Thinking a final object can't change. A final reference can't point elsewhere, but the object it points to can still change, unless it's immutable.

Interview Corner

Practice

1. Easy: Write one line of code showing each of: a final variable, a final method, a final class, and a finally block.
2. Harder: Try to reassign a final variable inside a finally block. What does the compiler say?

Key Takeaways