1Z0-811 Inheritance and Polymorphism

Question 1

Which keyword is used in Java to create a subclass that inherits from a parent class?

Accepted Answer

extends

Answer

The 'extends' keyword is used to create a subclass that inherits fields and methods from a parent class.

Question 2

How many classes can a Java class directly extend?

Accepted Answer

Only one

Answer

Java supports single inheritance for classes, meaning a class can only directly extend one other class.

Question 3

What does calling 'super()' inside a constructor do?

Accepted Answer

Calls the parent class constructor

Answer

When 'super()' is used in a constructor, it calls the parent class's constructor to initialize inherited fields.

Question 4

Which access modifier makes a member accessible to subclasses in different packages but not to unrelated classes?

Accepted Answer

protected

Answer

The 'protected' access modifier allows access from subclasses regardless of package and from classes within the same package.

Question 5

Are constructors inherited by subclasses in Java?

Accepted Answer

No, constructors are not inherited

Answer

Constructors are not inherited in Java; however, subclasses can call parent constructors using super().

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