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Java Exception Handling MCQ Test

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instanceof operator

In Java, the `instanceof` operator is used to check whether an object is an instance of a particular class or implements a particular interface. It returns `true` if the object is an instance of the specified class or implements the specified interface; otherwise, it returns `false`.

Syntax:

object instanceof ClassName

or

object instanceof InterfaceName


- `object`: The object whose type is to be checked.

- `ClassName`: The name of the class.

- `InterfaceName`: The name of the interface.


Example:


class Animal {}

class Dog extends Animal {}

class Cat extends Animal {}

public class Main {

    public static void main(String[] args) {

        Animal a = new Dog();

        System.out.println(a instanceof Animal); // true

        System.out.println(a instanceof Dog);    // true

        System.out.println(a instanceof Cat);    // false

    }

}


In this example:

- `a instanceof Animal` returns `true` because `a` is an instance of `Animal`.

- `a instanceof Dog` returns `true` because `a` is also an instance of `Dog`.

- `a instanceof Cat` returns `false` because `a` is not an instance of `Cat`.


Usage:

- Useful for checking the type of objects before performing operations or casting.

- Helps in implementing polymorphic behavior and dynamic dispatch.


Note:

- The `instanceof` operator returns `false` if the object is `null`.

- It's often used in conjunction with conditional statements, casting, and polymorphism to write more flexible and robust code.

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