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(); } }

Parameterized ConstructorDefault Constructor

Java Constructors

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Question 1

Which of the following is true about Java constructors?

A
Constructors have a return type of void.
B
Constructors must always be public.
C
A constructor is automatically called when an object is created.
D
Constructors can only be defined explicitly.

Question 2

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

A
The program will not compile.
B
The compiler provides a default constructor.
C
The class cannot be instantiated.
D
The constructor from another class will be used.

Question 3

Can a Java constructor be private?

A
No, it must be public.
B
Yes, but the class cannot be instantiated outside the class.
C
Yes, and it can be accessed from anywhere.
D
No, Java does not allow private constructors.

Question 4

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

A
Using super()
B
Using this()
C
Using new()
D
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();
    }
}

A
Default Constructor
B
Parameterized Constructor
C
Parameterized Constructor
Default Constructor
D
Compilation Error

Question 6

Can a constructor be final in Java?

A
Yes, if you override it.
B
No, because constructors are not inherited.
C
Yes, but only in abstract classes.
D
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();
    }
}

A
Base Constructor
Derived Constructor
B
Derived Constructor
Base Constructor
C
Compilation Error
D
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();
    }
}

A
Compilation Error
B
Private Constructor
C
Runtime Error
D
No Output

Question 9

What is the purpose of a constructor?

A
Destroy objects
B
Allocate memory
C
Initialize objects
D
Call main() method

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