Java Final vs Finally vs Finalize

Hello there, fellow Java enthusiasts! Today, we’re going to dive into a topic that often causes confusion among Java learners: the difference between final, finally, and finalize. These three terms might sound similar, but they serve entirely different purposes in Java. So, buckle up, and let’s demystify these concepts together!

Understanding Java’s Final Keyword

The final keyword in Java is used to restrict users. When you declare a variable as final, its value can’t be modified, it becomes a constant. Let’s see an example:

final int MAX_SPEED = 100;

In this case, the MAX_SPEED variable is declared as final, meaning its value is constant and cannot be changed later in the code.

Similarly, you can use the final keyword with methods and classes. A final method cannot be overridden by any subclass, and a final class cannot be subclassed. This is particularly useful when you want to make sure that your method implementation remains constant and that no other class can extend your class.

Understanding Java’s Finally Block

Moving on to finally, it’s a block of code used in exception handling. The finally block always executes, regardless of whether an exception is thrown or not. It’s usually used for cleanup code. Here’s an example:

try {
    // risky code
} catch (Exception e) {
    // handling exception
} finally {
    // cleanup code
}

In this example, no matter what happens in the try and catch blocks, the finally block will always execute, ensuring that the cleanup code runs.

Understanding Java’s Finalize Method

Last but not least, we have finalize. It’s a special method in Java that the garbage collector calls before collecting objects that are eligible for garbage collection. It’s usually overridden to clean up system resources, like closing files or network connections. Here’s an example:

protected void finalize() {
    // cleanup code
}

In this example, the finalize method is overridden to include cleanup code that runs right before the object is garbage collected.

Understanding Java’s Final, Finally and Finalize with Diagram

The diagram illustrates the basic concepts of final, finally, and finalize in Java.

• Final is a keyword used to apply restrictions. When applied to a variable, it becomes a constant. When applied to a method, it becomes non-overridable, meaning it cannot be overridden in a subclass. When applied to a class, it becomes non-subclassable, meaning it cannot be extended by another class.
• Finally is a block of code that always executes, regardless of whether an exception is thrown or not. It’s typically used for cleanup code, like closing connections or streams.
• Finalize is a method that is called by the garbage collector before an object is collected. It’s usually overridden to clean up system resources, like closing files or network connections.

Each of these concepts plays a crucial role in Java programming, and understanding them can help you write more efficient and effective code.

Code Examples

Let’s put these concepts into practice with a couple of code examples.

Example 1: Using Java final with variables, methods, and classes

// Using final with a variable
final int MAX_SPEED = 100;

// Using final with a method
public final void showMaxSpeed() {
    System.out.println("The max speed is " + MAX_SPEED);
}

// Using final with a class
public final class Vehicle {
    // class code
}

In this example, we’re using the final keyword in three different ways. First, we declare a final variable MAX_SPEED. This means MAX_SPEED is a constant, and its value can’t be changed once it’s set. Next, we declare a final method showMaxSpeed(). This method can’t be overridden in a subclass. Finally, we declare a final class Vehicle. This class can’t be extended by any other class.

Example 2: Using Java finally in exception handling

try {
    int result = 10 / 0;   // This will throw an ArithmeticException
} catch (ArithmeticException e) {
    System.out.println("Caught an exception");
} finally {
    System.out.println("This will always run");
}

Here, we’re demonstrating the use of the finally block in exception handling. We have a try block that will throw an ArithmeticException because we’re trying to divide by zero. This exception is caught in the catch block, where we print a message. Regardless of whether the exception was thrown and caught, the finally block will execute. This is why we see the message “This will always run” printed out.

Example 3: Overriding the Java finalize method

class Vehicle {
    // Some fields and methods

    public void finalize() {
        System.out.println("The Vehicle object is being garbage collected");
    }
}

In this example, we’re overriding the finalize method in the Vehicle class. The finalize method is called by the garbage collector before it collects an object. Here, we’re using it to print a message before the Vehicle object is garbage collected. This could be replaced with any cleanup code necessary, such as closing files or network connections.

Conclusion

In this tutorial, we’ve explored the differences between final, finally, and finalize in Java. We’ve learned that final is a keyword that makes variables constant, methods non-overridable, and classes non-subclassable. finally is a block of code that always executes after a try-catch block, and finalize is a method that the garbage collector calls before collecting objects. Understanding these concepts is crucial for mastering Java, so make sure to practice with your own code examples!

Frequently Asked Questions (FAQ)

Related Tutorials

• Understanding Java’s Garbage Collection
• Deep Dive into Java’s Exception Handling
• Mastering Java’s Class and Object Concepts
• Exploring Java’s Access Modifiers: Private, Public, and Protected
• Understanding and Implementing Java’s Abstract Classes and Interfaces

That’s it for this tutorial! We hope you found it helpful. Happy coding!