37. OCR A Level (H446) SLR7 – 1.2 Object-oriented languages part

What is the primary mechanism provided by OOP for allowing a class to acquire the properties and methods of another class?

• Encapsulation

• Abstraction

• Inheritance

• Polymorphism

Answer explanation

Inheritance is the primary mechanism in OOP for a class to acquire properties and methods from another class.

How many methods are associated with every object created from the generic light bulb class?

• Four

• Six

• Ten

• Eight

Answer explanation

Every object created from the generic light bulb class has eight methods associated with it, making the correct answer choice 'Eight'.

What term is used to refer to the original class from which a new class inherits properties in OOP?

• Subclass

• Derived class

• Superclass

• Child class

Answer explanation

The term used to refer to the original class from which a new class inherits properties in OOP is 'Superclass'.

What additional attribute might an 'Employee' class, which inherits from the 'Person' class, include?

• Date of Birth

• Height

• National Insurance Number

• Favorite Color

Answer explanation

An 'Employee' class might include the 'National Insurance Number' attribute as it is often required for employment purposes and distinguishes an employee from a person.

How many attributes does an hourly paid employee object have, considering inheritance from 'Person' and 'Employee' classes?

• Three

• Four

• Two

• Five

Answer explanation

The hourly paid employee object has four attributes due to inheritance from 'Person' and 'Employee' classes, which contribute to the total count.

What happens when a subclass defines a method that has the same name as a method in its superclass?

• The subclass method is ignored

• The subclass method overrides the superclass method

• The program crashes

• The superclass method is automatically deleted

Answer explanation

When a subclass defines a method with the same name as a method in its superclass, the subclass method overrides the superclass method, allowing the subclass to provide its own implementation.

What keyword is used to access a method from the original superclass when it has been overridden in a subclass?

• parent

• super

• base

• original

Answer explanation

The keyword 'super' is used to access a method from the original superclass when it has been overridden in a subclass.

How many methods does a salaried employee object have?

• Seven

• Six

• Nine

• Eight

Answer explanation

A salaried employee object has eight methods, making the correct answer choice Eight.

What prefix is used for the name of a salaried employee in the system?

• E_

• S_

• P_

• H_

Answer explanation

The prefix 'S_' is used for the name of a salaried employee in the system, making it the correct choice.

What keyword is used to indicate that a class inherits from another class?

• extends

• implements

• inherits

• derives

Answer explanation

The keyword 'inherits' is used to indicate that a class inherits from another class in object-oriented programming.