Inheritance and Polymorphism Flashcards

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

Answer: extends

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

How many classes can a Java class directly extend?

Answer: Only one

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

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

Answer: Calls the parent class constructor

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

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

Answer: protected

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

Are constructors inherited by subclasses in Java?

Answer: No, constructors are not inherited

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

What is the implicit parent class of every Java class that does not explicitly extend another class?

Answer: java.lang.Object

Every Java class implicitly extends java.lang.Object if no other parent class is specified.

Given: class Animal {} and class Dog extends Animal {}, which statement is true?

Answer: Dog is a type of Animal

In an 'is-a' relationship, Dog is a type of Animal because Dog extends Animal, inheriting its behavior.