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Final Class In Java: Java Explained

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Java is a widely used language, with many advanced features that help developers create complicated coding projects. One of these features is the ability to make classes “final”, or unchangeable. In this article, we will explain what a final class in Java is and how to use it, the many benefits of using a final class, how to create and access them, common uses for final classes, best practices to keep in mind, and potential troubleshooting issues.

What Is A Final Class In Java?

A final class in Java is a type of class that cannot be extended or modified in any way. Specifically, it is declared with the keyword “final”, which makes it a type of “immutable” class, meaning that once it is defined, it cannot be changed or altered in any way. This makes the final class particularly beneficial when you need a guarantee that a given code will remain unchanged throughout development.

Final classes are also useful for preventing inheritance, as they cannot be extended. This can be beneficial when you want to ensure that a class is not modified or extended in any way, as it can help to maintain the integrity of the code. Additionally, final classes can help to improve the performance of your code, as the compiler can optimize the code more efficiently when it knows that the class cannot be changed.

Benefits of Using Final Classes

Final classes are widely used across Java development due to their numerous benefits:

  • Reliability and predictability: As indicated above, making a class final ensures that it cannot be changed or altered in any form, making the code more predictable and reliable.
  • Performance improvement: Final classes can improve system performance due to less (or no) code changes after their definition. This means that the program can perform more efficiently without having to process any code changes.
  • Flexible coding: Making a class final allows developers to write code that is flexible and can be adapted to different situations without compromising the reliability of the code.

In addition, final classes can help to reduce the complexity of the codebase, as they are not subject to change and can be used as a reference point for other classes. This makes it easier for developers to understand the code and make changes as needed.

How To Create A Final Class In Java

Creating a final class in Java is relatively simple. All you need to do is define the class with the keyword “final” — this can be done either when you declare the class (e.g. “final public class MyClass”) or when you declare particular methods (“final public void mymethod()”). Once you have declared the class as final, no further modifications can be made.

It is important to note that once a class is declared as final, all of its methods and variables are also considered final. This means that they cannot be modified or overridden. Additionally, any class that extends a final class will also be considered final, as it cannot be modified or extended.

How To Access Final Classes

Accessing final classes is no different from accessing non-final classes. You can access a final class using the typical Java syntax (i.e. ClassName.method() or new ClassName()) and then call any public methods defined in the class. To summarise, the only difference between accessing a final class and a non-final class is that the former cannot be changed.

It is important to note that final classes are not necessarily immutable. While the class itself cannot be changed, the objects created from the class can still be modified. For example, a final class may contain a mutable field, which can be changed after the object is created. Therefore, it is important to understand the implications of using a final class before deciding to use it in your code.

Common Uses Of Final Classes

Final classes have a variety of uses in Java development. Most frequently, they are used to create immutable objects — objects that cannot be modified or altered in any way. This ensures reliable and predictable behaviour of code even when different user requests are made. Common uses of final classes include creating utility classes, providing better control over instances of objects, or simply creating an immutable object.

Final classes can also be used to prevent inheritance, which can be useful when you want to ensure that a class cannot be extended or modified. This can be beneficial when you want to ensure that the code remains consistent and reliable. Additionally, final classes can be used to improve the performance of an application, as the compiler can optimize the code more efficiently when it knows that the class cannot be extended.

Examples of Final Classes In Java

An example of a final class in Java might look like this:

public final class MyClass {        public String message;    public MyClass(String msg) {        this.message = msg;    }    public void show() {        System.out.println(this.message);    }}

In the code above, MyClass has been declared as “final”, meaning that it cannot be extended or modified in any way.

Best Practices For Using Final Classes In Java

Although there are many advantages to using final classes, it is important to use them responsibly. Some best practices to keep in mind include:

  • Avoid making all your classes and functions final: Although using final classes can be beneficial, it should not be applied to each and every class or function as this can lead to an overly rigid code base and will hamper flexibility.
  • Make only necessary methods of a class final: Making only certain methods of a class final helps maintain flexibility while still guaranteeing the reliability of important parts of the code.
  • Avoid making long chains of final classes: Making too many consecutively nested final classes is not recommended as this can lead to unwieldy code and can become difficult to maintain or change if needed.

Troubleshooting Common Issues With Final Classes

As with any type of programming, there may be occasions when there are issues related to the use of final classes. Common issues include:

  • Inability to access private members of parent classes: If a child class attempts to access private members of its parent class, it will be unable to do so (as these are not inherited by child classes).
  • Not being able to extend classes: As indicated above, when dealing with a final class it is not possible for child classes to extend it. This can make certain coding projects difficult to complete as multiple classes may rely on each other’s properties and methods.
  • Poor performance due to limited flexibility: As stated earlier, although final classes provide better control over code’s unpredictability, they may also lead to poor performance as they cannot be changed or adapted when needed.

Conclusion

In this article, we have discussed final classes in Java — what they are, their benefits and uses, how to create them and access them, best practices to keep in mind, and common troubleshooting issues you may experience when dealing with them. Final classes are a powerful tool for developers and if used correctly they can help ensure reliable and predictable code while keeping performance high.

Anand Das

Anand Das

Anand is Co-founder and CTO of Bito. He leads technical strategy and engineering, and is our biggest user! Formerly, Anand was CTO of Eyeota, a data company acquired by Dun & Bradstreet. He is co-founder of PubMatic, where he led the building of an ad exchange system that handles over 1 Trillion bids per day.

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