Java is a popular programming language known for its reliability and flexibility. One of its unique features is the “final” keyword. While it may seem like just another keyword, its use can significantly impact the functionality and structure of your Java code. If you looking for the answer to what is the use of final keyword in Java the here you will get the answer.
In this blog, we will explore the various uses of the final keyword in Java and how it can enhance the readability, maintainability, and performance of your code. So, if you’re a Java programmer looking to improve your skills or just curious about the final keyword, keep reading!
The “final” keyword in Java is a powerful tool that helps to enforce certain constraints in a program. It provides a way to declare variables, methods, and classes as unmodifiable, which can be useful in situations where immutability is desirable.
This feature is particularly useful for improving the security, reliability, and performance of code. By understanding the use of the final keyword, Java developers can create more efficient, maintainable, and scalable applications.
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What is the final keyword in JAVA?
Table of Contents
“Final” is a modifier that provides the restriction. In Java, we can use the final in three ways.
In Java, the ‘final’ keyword indicates that a variable, method, or class cannot be overridden or modified.
What is the final Variable?
Once we declare a variable as a final, we can’t perform re-assignment.
For Example
syntax :- final int B=10;
Note:- In Java, the final variable’s first alphabet is always written in an uppercase letter like you can see above. We have declared a final variable.
Program for Final Variable declaration
class math {
public static void main(String[] args) {
final int Math=30;
System.out.println(Math);
}
}
Output
30
Program snapshot with output.
Output
Suppose we want to change the variable value can; is it possible? Let’s checked
- Program
class math {
public static void main(String[] args) {
final int MATH=30;
System.out.println(MATH);
MATH=82;
System.out.println(MATH);
}
}
Output
/tmp/JdNgZMp6uN/math.java:9: error: cannot assign a value to final variable MATH
MATH=82;
^
1 error
Also read: JavaScript Remove Duplicates From Array
Program snapshot with output
Output
One more example of that
Program
class total_subject {
public static void main(String[] args) {
final int Subject=5;
System.out.println(Subject);
Subject=6;
//now we want to add one more subject, so we assign a new value to the Subject variable. But after making the final (Subject) variable, it is not possible.
System.out.println(Subject);
}
}
Output
/tmp/fO1VAXNjXD/total_subject.java:7: error: cannot assign a value to final variable Subject
Subject=6;
^
1 error
Program snapshot with output
Output
What is the final Method?
Whenever we declare a method as a final, it can’t be overridden by our extended class.
We need to create a final method when we want nobody to use our code which is mentioned in the main method. Then, we create this main method as a final method.
Syntax:- final void English1()
{
}
- Program
class Owner
{
void mNumber()
{
System.out.println("(123)456-7890");
}
void atmPIN()
{
System.out.println("365");
}
}
class Thirdparty extends Owner
{
@Override
void mNumber()
{
System.out.println("(123) 456-7890");
}
@Override
void atmPIN()
{
System.out.println("365");
}
}
class Final
{
public static void main(String[] args) {
Thirdparty t=new Thirdparty();
t.mNumber(); t.atmPIN();
}
}
Output
(123) 456-7890
365
Program snapshot with output
In program no 3, You can see thirdparty class access all the data of the owner class.
Output
Now, if you don’t want to access third party class atmPin data from the Owner program, then you can use the final method. For example, please look into the below program.
- Program
class Owner
{
void mNumber()
{
System.out.println("(123)456-7890");
}
final void atmPIN()
{
System.out.println("365");
}
}
class Thirdparty extends Owner
{
@Override
void mNumber()
{
System.out.println("(123) 456-7890");
}
@Override
void atmPIN()
{
System.out.println("365");
}
}
class Final
{
public static void main(String[] args) {
Thirdparty t=new Thirdparty();
t.mNumber(); t.atmPIN();
}
}
Output
/tmp/NOzZ6VROOq/Final.java:23: error: atmPIN() in Thirdparty cannot override atmPIN() in Owner
void atmPIN()
^
overridden method is final
1 error
Program snapshot with output
Now you can see we make the final method of void atmPIN() in this program.
Output
What is the final Class?
Whenever we declare a class as a final, it can’t be extended or inherited to sub-classes.
Syntax:- final class A
{
}
- Program
class Owner
{
void mNumber()
{
System.out.println("(123)456-7890");
}
void atmPIN()
{
System.out.println("365");
}
}
class Thirdparty extends Owner
{
@Override
void mNumber()
{
System.out.println("(123) 456-7890");
}
@Override
void atmPIN()
{
System.out.println("365");
}
}
class Final
{
public static void main(String[] args) {
Thirdparty t=new Thirdparty();
t.mNumber(); t.atmPIN();
}
}
Output
(123) 456-7890
365
Program snapshot with output
In this program, we have used two inherited data classes as sub-classes.
Output
If we want nobody to access any method or data which is used in one class. Then we make this class a final class.
- Program
final class Owner
{
void mNumber()
{
System.out.println("(123)456-7890");
}
void atmPIN()
{
System.out.println("365");
}
}
class Thirdparty extends Owner
{
@Override
void mNumber()
{
System.out.println("(123) 456-7890");
}
@Override
void atmPIN()
{
System.out.println("365");
}
}
class Final
{
public static void main(String[] args) {
Thirdparty t=new Thirdparty();
t.mNumber(); t.atmPIN();
}
}
Output
/tmp/NOzZ6VROOq/Final.java:15: error: cannot inherit from final Owner
class Thirdparty extends Owner
^
1 error
Program snapshot with output
Output
Why use final in Java?
The final keyword in Java is used to indicate that a variable, method, or class cannot be overridden or modified, This can be useful in a variety of situations:
Immutable objects
Making an object final can ensure its state cannot be modified, making it useful for creating immutable objects.
Security
By making a variable or method final, you can prevent it from being overridden in a malicious subclass, which can be useful for security-sensitive code.
Performance
Marking a method as final can improve performance because the Java compiler can make certain optimizations knowing that the method cannot be overridden.
Design
Making a class final can be useful to prevent it from being subclassed and ensure that the class’s behavior cannot be overridden.
Functional programming
By making a variable final, it can be passed as an argument to a lambda expression, which helps in functional programming.
Advantages Of Final Keyword In JAVA
The “final” keyword in Java has several advantages:
- It can indicate that a variable’s value cannot be changed once it is initialized. This can help prevent accidental changes and improve code readability.
- It can indicate that a subclass cannot override a method. This can be useful for ensuring that certain methods always behave in a certain way.
- It can be used to indicate that a class cannot be subclassed. This can be useful for creating immutable classes or for preventing certain types of inheritance.
- It can be used to indicate that a parameter of a method or constructor is final, which can help prevent accidental changes to the parameter’s value within the method or constructor.
- It can help to improve the performance of the program. Since final variables are constants and the JIT (Just-In-Time) compiler can optimize the code more effectively when it knows that the value of a variable will never change.
Disadvantages Of Final Keyword In JAVA
The “final” keyword in Java also has some disadvantages:
- It can make the code less flexible, as once a variable or method is declared final, it cannot be changed or overridden.
- It can make the code harder to maintain, as it can be difficult to understand the suggestion of a final variable or method without carefully reading the code.
- It can make the code less expressive, as it can be difficult to convey the intent of a final variable or method without additional documentation.
- It can make the code less maintainable, as it can be difficult to change the codebase when final variables or methods are present.
Conclusion
In this article, we have discussed “What Is The Use Of Final Keyword In JAVA” we hope you are fully satisfied with our knowledge. You can better understand clearly the final keyword in Java. This is helpful to you. After all clarification, you can use this keyword easily with a good understanding of your program.
FAQ( Frequently Asked Questions)
What is the use of the final keyword in Java?
The “final” keyword in Java has three main uses:
To indicate that a variable’s value cannot be changed once it is initialized. This can help prevent accidental changes and improve code readability.
To indicate that a class cannot be subclassed. This can be useful for creating fixed classes or for preventing certain types of inheritance.
What is the use of static and final keywords in Java?
In Java, the “static” keyword is used to indicate that a variable or method belongs to a class rather than an instance of the class. This means that the variable or method can be accessed without creating an instance of the class. The “final” keyword indicates that a variable’s value cannot be changed or that a method cannot be overridden.