Core Java Interview Questions and Answers: Question 41 to Question 50
Here you can find the 100+ most frequently asked important core java interview questions and answers (41 to 50) for placement (campus) interview and competitive examinations.
41. What is the use of an abstract variable?
Answer: Variables can’t be declared as abstract. only classes and methods can be declared as abstract.
42. Can you create an object of an abstract class?
Answer: Not possible. Abstract classes can’t be instantiated.
43. Can a abstract class be defined without any abstract methods?
Answer: Yes it’s possible. This is basically to avoid instance creation of the class.
44. Class C implements Interface I containing method m1 and m2 declarations.
Class C has provided implementation for method m2. Can i create an object of Class C?
Answer: No not possible. Class C should provide an implementation for all the methods in the Interface I. Since Class C didn’t provide an implementation for the m1 method, it has to be declared as abstract. Abstract classes can’t be instantiated.
45. Can a method inside an Interface be declared as final?
Answer: No not possible. Doing so will result in a compilation error. public and abstract are the only applicable modifiers for method declaration in an interface.
46. Can an Interface implement another Interface?
Answer: An Inteface doesn’t provide implementation hence an interface cannot implement another interface.
47. Can an Interface extend another Interface?
Answer: Yes an Interface can inherit another Interface, for that matter, an Interface can extend more than one Interface.
48. Can a Class extend more than one Class?
Answer: Not possible. A Class can extend only one class but can implement any number of Interfaces.
49. Why is an Interface be able to extend more than one Interface but a Class can’t extend more than one Class?
Answer: Basically Java doesn’t allow multiple inheritances, so a Class is restricted to extend only one Class. But an Interface is a pure abstraction model and doesn’t have an inheritance hierarchy like classes(do remember that the base class of all
classes is Object). So an Interface is allowed to extend more than one Interface.
50. Can an Interface be final?
Answer: Not possible. Doing so so will result in compilation error.
Summary
Here you can find the 100+ frequently asked important Core Java Interview Questions and Answers 41 to 50. If you like the material share it with your friends. Like the Facebook page for regular updates and YouTube channel for video tutorials.