final keyword in java?

In Java, the final keyword is used to stop changes.
It can be used with variables, methods, and classes.

• If a variable is final, its value cannot be changed.
• If a method is final, it cannot be overridden.
• If a class is final, it cannot be inherited.

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1. Final Variable

A final variable can only be assigned once.

final int x = 10;
x = 20; //  Error: cannot change value

• Acts like a constant
• Must be initialized once (either at declaration or in constructor)

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2. Final Method

A final method cannot be overridden by subclasses.

class Parent {
    final void show() {
        System.out.println("Final method");
    }
}

class Child extends Parent {
    void show() { //  Error
        System.out.println("Cannot override");
    }
}

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3. Final Class

A final class cannot be inherited (extended).

final class Animal {}

class Dog extends Animal { //  Error
}

Example:

• String class in Java is final