OOPS Concepts Test Questions

A polymorphism can be called what?

• A relationship between two objects.
• The order of objects in a sequence.
• A function that performs in different ways.
• Functions that perform the same way.

Answer: A function that performs in different ways.

How can dynamic binding be contrasted with static binding?

• They are bound together with polymorphic compiling.
• Dynamic binding is compile time binding, while static binding is runtime binding.
• Static binding is better than dynamic binding.
• Dynamic binding is runtime binding, while static binding is compile time binding.

Answer: Dynamic binding is runtime binding, while static binding is compile time binding.

What is a simple way to think of inheritance?

• One object generating another object.
• One object acquiring the properties of another.
• One object writing new properties for another.
• New properties written from scratch.

Answer: One object acquiring the properties of another.

When does binding occur with static binding?

• At runtime.
• Never.
• At compile time.
• After runtime binding occurs.

Answer: At compile time.

A clone method is needed to:

• make any copies of the parent object
• make any copies of children objects
• to create a second copy of all contained subobjects
• make any copies of this object

Answer: to create a second copy of all contained subobjects

What are classes used for?

• Classes are used to manage metadata.
• Classes define objects.
• Classes are used to define specific types.
• Classes describe different features.

Answer: Classes are used to define specific types.

Programming languages supporting the OOPS paradigm are typically contained within what two classes?

• Logic-based and inference-based.
• Prototype-based, or class-based.
• System based and program-based.
• OOPS-based and object-based

Answer: Prototype-based, or class-based.

When two methods have the same name, what are they considered, and what kind of binding do they have?

• Overloaded, static.
• Overloaded, late.
• Overloaded, dynamic.
• Overhauled, static.

Answer: Overloaded, static.

What is a primary motivation for using OOP?

• To increase speed of writing code.
• To increase reusability and maintainability of code.
• To increase data coupling.
• Because other programming paradigms have become obsolete.

Answer: To increase reusability and maintainability of code.

Ref counts are:

• a way of managing object lifetimes
• how wrestling referees determine a winner
• magic methods on all classes
• an optimization for compilers

Answer: a way of managing object lifetimes

When a variable is defined within a class, what is it considered?

• A varying variable.
• An early variable.
• A class variable.
• An instance variable.

Answer: An instance variable.

Why is dynamic binding referred to as “late binding”?

• It is not bound at compile time.
• It is bound at compile time.
• It is not bound at runtime.
• It is never bound.

Answer: It is not bound at compile time.

Static functions can use which variables?

• private and static
• public
• private
• static

Answer: static

What are objects identified by?

• Their qualities.
• Their relationship with other objects.
• Their orientation within a program.
• Their unique name.

Answer: Their unique name.

Which of the following could be considered a polymorphism?

• Two classes named “clsCalculation” with the single function, “add”.
• Two functions named “clsCalculation”.
• The class, “clsCalculation” with two functions, both named “Add”.
• Two classes named “add”.

Answer: The class, “clsCalculation” with two functions, both named “Add”.

Can an object have more than one instance?

• Yes.+58pts
• No.
• Yes, but they must be in two different physical locations.
• Yes, but it will result in errors.

Answer: Yes

A mutator method is also known as a:

• Setter
• deleter
• updater
• getter

Answer: Setter

True or false? Static variables are visible outside of the class

• depends
• False
• True

Answer: depends

An abstract class can:

• Be subclassed
• Only contain abstract methods
• Be instantiated

Answer: Be subclassed

A trait is:

• another word for class
• another word for interface
• a collection of methods

Answer: a collection of methods

What is the difference between interfaces and abstract classes?

• interfaces cannot have methods whereas abstract classes can
• interfaces cannot have properties whereas abstract classes can
• abstract classes can provide default implementation whereas interfaces cannot provide implementations
• interfaces can provide default implementation whereas abstract classes cannot provide implementations

Answer: abstract classes can provide default implementation whereas interfaces cannot provide implementations

Why is composition considered a simpler method than inheritance?

• It isn't considered a simpler method.
• Composition has complex namespace clashes.
• It is filled with complicated inheritance hierarchies.
• Composition lacks the namespace clash, and the complicated inheritance hierarchies.

Answer: Composition lacks the namespace clash, and the complicated inheritance hierarchies.

True or false? Abstract methods are only defined in the parent.

• False
• True

Answer: False

True or false? Polymorphism means to support multiple inheritance.

• True
• False

Answer: False

What is the most important trait of a polymorphism?

• The common interface.
• The total differences.
• The multiple interfaces.
• The difference in interface.

Answer: The common interface.

True or false? It's legal to have two variables both named $count where one is a global variable and the other is used inside a class.

• only if $count is static in both uses
• False
• True

Answer: True

What are method names typically restricted by?

• Code conventions.
• The alphabet.
• Grammatical rules.
• Ethical rules.

Answer: Code conventions.

Which of the following is included in the field of formal semantics?

• The comprehension of relational models.
• The definition of semantic models.
• The understanding of programming models.
• The definition of logistic models.

Answer: The definition of semantic models.

What kind of relationship is the public class “Animal” with the extension, “Mammal” demonstrating?

• HAS-A Relationship
• IS-A Relationship
• WAS-A Relationship
• IS-NOT-A Relationship

Answer: IS-A Relationship

Lambda functions are allowed in class definitions

• False
• True

Answer: False