Suppose A is an abstract class, B is a concrete subclass of A, and both A and B have a default constructor. Which of the following is correct?
1. A a = new A();
2. A a = new B();
3. B b = new A();
4. B b = new B();
A. 1 and 2
B. 2 and 4
C. 3 and 4
D. 1 and 3
E. 2 and 3
Answer: Option B
This Question Belongs to Java Program >> Interfaces And Abstract Classes
Option 1. & 3. is wrong because we cant create object of abstract class.
2 & 4 are correct because B is concrete class and its object is created and in Option 2, reference of class A(abstract class) can be used to hold its child class's object.