1Z0-811 Inheritance and Polymorphism 2

Question 1

What is method overriding in Java?

Accepted Answer

Providing a new implementation of a parent class method in a subclass

Answer

Method overriding occurs when a subclass provides a specific implementation of a method already defined in its parent class with the same signature.

Question 2

Which annotation should be used when overriding a method to catch signature errors at compile time?

Accepted Answer

@Override

Answer

The @Override annotation tells the compiler to verify that the method actually overrides a parent method, catching errors if the signature doesn't match.

Question 3

Can a private method in a parent class be overridden by a subclass?

Accepted Answer

No, private methods are not inherited and cannot be overridden

Answer

Private methods are not visible to subclasses and therefore cannot be overridden; a subclass defining a same-name private method simply creates a new unrelated method.

Question 4

What is the rule regarding access modifiers when overriding a method?

Accepted Answer

The overriding method must have the same or broader (less restrictive) access modifier

Answer

An overriding method must have the same or broader (less restrictive) access modifier than the method it overrides.

Question 5

What is runtime polymorphism in Java?

Accepted Answer

Method overriding resolved at runtime based on the actual object type

Answer

Runtime polymorphism (dynamic dispatch) occurs when the JVM determines which overridden method to call based on the actual object type at runtime, not the reference type.

(1Z0-811) Oracle Java SE11 Programmer Practice Test

(1Z0-811) Oracle Java SE11 Programmer Practice Test

1Z0-811 Inheritance and Polymorphism 2