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Home Interviews What is the significance of the 'final' keyword in Java? – MindStick
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1 Answers

Ashutosh Patel
Ashutosh Patel 21 Jul 2024
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Final Keyword in Java

The key word ‘end’ is used to indicate that something cannot always be changed. It varies in importance according to its use:

Final Variables 

When applied to a variable, it means that the value of the variable cannot be changed once it is initialized.

Syntax-

final int x = 10;
// x = 20; // Compilation error: cannot assign a value to final variable x

Final Methods 

Used in a method, it means that subclasses cannot be placed on the method.

Syntax-

class Parent {
   final void display() {
       System.out.println("Parent's display method");
   }
}
class Child extends Parent {
   // Compilation error: Cannot override the final method from Parent
    void display() {
       System.out.println("Child's display method");
    }
}

Final Classes 

When applied to a class, it means that the class cannot be parsed (i.e. no other class can inherit from it).

Syntax-

final class FinalClass {
   // Class implementation
}
// Compilation error: Cannot inherit from final FinalClass
// class SubClass extends FinalClass {
//     // Class implementation
// }

Final Parameters 

When applied to a method parameter, it indicates that the parameter cannot be changed in the method.

Syntax- 

void printValue(final int num) {
   // num = 20; // Compilation error: cannot assign a value to final parameter num
   System.out.println("Value: " + num);
}

The 'final' keyword ensures immutability, prevents method execution, prohibits subclassing, or forces method parameters to remain unchanged within a method This provides code reliability, security, and performance up in Java programs.

Also, Read: What is a HashMap and how does it work?

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