Java Constructors (original) (raw)

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.

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.

What will be the output of the following Java code?

Java `

class Test { int x; Test() { x = 10; } } public class Main { public static void main(String[] args) { Test obj = new Test(); System.out.println(obj.x); } }

`

Can a Java constructor be private?

• 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.

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

• Constructors cannot call each other

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 Constructor
• Parameterized Constructor
  Default Constructor

What will happen if you explicitly define a constructor with parameters but do not define a no-argument constructor?

• Java will provide a default no-argument constructor.
• You cannot create an object without passing arguments.
• Compilation error occurs.
• The constructor will be inherited from Object class.

Can a constructor be final in Java?

• No, because constructors are not inherited.
• Yes, but only in abstract classes.
• Yes, but only for utility classes.

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

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(); } }

`

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