Java Constructors

    Last Updated :
    Discuss
    Comments

    Question 1

    Which of the following is true about Java constructors?

    • Constructors have a return type of void.

    • Constructors must always be public.

    • A constructor is automatically called when an object is created.

    • Constructors can only be defined explicitly.


    Question 2

    What happens if you do not define a constructor in a Java class?

    • The program will not compile.

    • The compiler provides a default constructor.

    • The class cannot be instantiated.

    • The constructor from another class will be used.


    Question 3

    Can a Java constructor be private?


    • No, it must be public.

    • Yes, but the class cannot be instantiated outside the class.

    • Yes, and it can be accessed from anywhere.

    • No, Java does not allow private constructors.

    Question 4

    How can one constructor call another constructor within the same class?

    • Using super()

    • Using this()

    • Using new()

    • Constructors cannot call each other


    Question 5

    What will be the output of this program?

    Java 
    class Demo {
    int num;
    Demo() {
        this(100);
        System.out.println("Default Constructor");
    }
    Demo(int n) {
        num = n;
        System.out.println("Parameterized Constructor");
    }
}
public class Main {
    public static void main(String[] args) {
        Demo obj = new Demo();
    }
}


    • Default Constructor

    • Parameterized Constructor

    • Parameterized Constructor
      Default Constructor

    • Compilation Error


    Question 6

    Can a constructor be final in Java?


    • Yes, if you override it.

    • No, because constructors are not inherited.

    • Yes, but only in abstract classes.

    • Yes, but only for utility classes.

    Question 7

    What will be the output of the following code?

    Java 
    class Base {
    Base() {
        System.out.println("Base Constructor");
    }
}
class Derived extends Base {
    Derived() {
        System.out.println("Derived Constructor");
    }
}
public class Main {
    public static void main(String[] args) {
        Derived obj = new Derived();
    }
}


    • Base Constructor
      Derived Constructor

    • Derived Constructor
      Base Constructor


    • Compilation Error

    • Runtime Error

    Question 8

    What will be the output of this program?

    Java 
    class A {
    private A() {
        System.out.println("Private Constructor");
    }
    public static void createInstance() {
        new A();
    }
}
public class Main {
    public static void main(String[] args) {
        A.createInstance();
    }
}


    • Compilation Error

    • Private Constructor

    • Runtime Error


    • No Output

    Question 9

    What is the purpose of a constructor?


    • Destroy objects

    • Allocate memory

    • Initialize objects

    • Call main() method

    There are 9 questions to complete.

    Take a part in the ongoing discussion