Exploring Superclasses and Subclasses in AP CS A

This video tutorial introduces the concepts of superclasses and subclasses in programming. It explains the 'has-a' and 'is-a' relationships with examples, such as the relationship between a student and a person. The tutorial discusses common and specific attributes in classes, and how to create superclass-subclass relationships using the 'extends' keyword. It also covers implementation details and the importance of class hierarchy for code reuse and polymorphism.

What does a 'has a' relationship in classes represent?

• Instance variables within a class

• A method within a class

• A superclass extending a subclass

• A subclass extending a superclass

What is true about the 'is a' relationship?

• It describes a more specific version of something

• A student has a person

• It is always symmetrical

• Every person is a student

What is an example of an 'is a' relationship?

• Every dog is an animal

• A worker has a job title

• A person has a name

• A student has a person

Which attribute would only be found in a Student class and not in a Person class?

• Name

• Job title

• Birthday

• Grade

Which class would have a method to calculate GPA?

• Person

• Student

• Animal

• Worker

What is the purpose of a superclass?

• To prevent code reuse

• To store specific attributes of a subclass

• To create a 'has a' relationship

• To allow subclasses to inherit common attributes

How do you create a subclass from a superclass?

• Using the 'extends' keyword

• By copying all attributes from the superclass

• Subclasses cannot be created from superclasses

• Using the 'implements' keyword

Can a subclass extend multiple superclasses?

• Yes, it can extend any number of superclasses

• No, subclasses cannot extend superclasses

• Yes, but only if they are related

• No, it can only extend one superclass

What does inheritance in object-oriented programming allow?

• A superclass to access attributes of a subclass

• Subclasses to inherit attributes from multiple superclasses

• Preventing subclasses from accessing superclass attributes

• Subclasses to inherit attributes and behaviors from a superclass

What is true about the relationship between HighSchoolStudent, Student, and Person classes?

• Student class is a superclass of Person class

• Person class can access attributes of Student and HighSchoolStudent classes

• HighSchoolStudent can access attributes of both Student and Person classes

• HighSchoolStudent is a superclass of Student class