What is the difference between `final`, `finally`, and `finalize` in Java?

Q: What is the difference between `final`, `finally`, and `finalize` in Java?

Learn the answer to "What is the difference between `final`, `finally`, and `finalize` in Java?" with detailed explanations, code examples, and best practices on DeployU.

The Scenario

You are a backend engineer at a fintech company. You are writing a new service that needs to work with a variety of different data types.

The Challenge

Explain the difference between the final, finally, and finalize keywords in Java.

Wrong Approach

A junior engineer might confuse these three keywords. They might not be aware of the difference in their purpose or how they are used.

Addresses symptoms, not root cause

Right Approach

A senior engineer would be able to provide a detailed explanation of the differences between `final`, `finally`, and `finalize`. They would also be able to explain the trade-offs between each approach and would have a clear recommendation for which one to use in a given situation.

Step 1: Understand the Key Differences

Keyword	Description
`final`	A keyword that can be used to make a variable, method, or class immutable.
`finally`	A block of code that is always executed, regardless of whether an exception is thrown.
`finalize`	A method that is called by the garbage collector just before an object is garbage collected.

Step 2: Code Examples

Here are some code examples that show the difference between the three keywords:

final:

public class MyClass {
    public final int MY_CONSTANT = 10;

    public final void myMethod() {
        // ...
    }
}

finally:

try {
    // ...
} catch (Exception e) {
    // ...
} finally {
    // This block is always executed.
}

finalize:

public class MyClass {
    @Override
    protected void finalize() throws Throwable {
        // This method is called by the garbage collector.
    }
}

When to use each

Use final to create constants and to prevent a method or class from being overridden.
Use finally to release resources, such as file handles and database connections.
Avoid using finalize. It is not guaranteed to be called, and it can make your code more difficult to reason about.

Systematic, production-ready debugging

Practice Question

You are writing a function that opens a file. Which of the following would be the most appropriate way to close the file?

Questions