Java Inheritance and Abstraction

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    Question 1

    Which of the following statements about the Object class in Java is true?


    • Every Java class extends Object class either directly or indirectly.

    • Only classes without a superclass extend Object class.

    • The Object class cannot be extended.


    • Object class is an abstract class.


    Question 2

    What will be the output of the following code?

    Java 
    class A {
    void display() {
        System.out.println("Class A");
    }
}
class B extends A {
    void display() {
        System.out.println("Class B");
    }
}
public class Main {
    public static void main(String[] args) {
        A obj = new B();
        obj.display();
    }
}


    • Class A

    • Class B

    • Compilation error

    • Runtime error

    Question 3

    Which keyword is used to create a subclass in Java?

    • implements

    • inherits

    • extends

    • interface

    Question 4

    What is abstraction in Java?

    • Hiding method names

    • Hiding internal implementation and showing only functionality

    • Creating private variables

    • Inheriting classes

    Question 5

    Which keyword is used to define an abstract class?


    • interface

    • abstract


    • static

    • private


    Question 6

    What happens if an abstract class does not have any abstract methods?

    • It will not compile.

    • The class can still be abstract.

    • Java will automatically provide an abstract method.

    • It becomes a concrete class.

    Question 7

    Which of the following statements about inheritance is false?


    • Java supports single inheritance.

    • Java allows multiple class inheritance using extends.

    • Interfaces can be used to achieve multiple inheritance.


    • The super keyword can be used to invoke the parent class constructor.


    There are 7 questions to complete.

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