Java Constructors

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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.


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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.


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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.

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Question 4

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

  • Using super()

  • Using this()

  • Using new()

  • Constructors cannot call each other


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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


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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.

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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

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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

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Question 9

What is the purpose of a constructor?


  • Destroy objects

  • Allocate memory

  • Initialize objects

  • Call main() method

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There are 9 questions to complete.

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