Polymorphism Overview and Interfaces Quiz
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Questions and Answers

What does polymorphism enable you to do?

program in the general

Which of the following is false about interfaces?

  • An interface describes a set of methods that can be called on an object, providing a default implementation for the methods.
  • An interface only defines methods without implementation.
  • An interface can contain method implementations. (correct)
  • An interface cannot specify any member variables.

What does polymorphism specifically enable the creation of programs that handle?

a wide variety of classes in a general manner

Polymorphism allows classes to be added with little or no modifications to the generic portion of a program.

<p>True (A)</p> Signup and view all the answers

When used correctly, polymorphism will never require changes to be made to any part of the program.

<p>False (B)</p> Signup and view all the answers

Unfortunately, polymorphic programs make it difficult to add new capabilities to a system.

<p>False (B)</p> Signup and view all the answers

Polymorphism enables objects of different classes that are related by a class hierarchy to be processed generically.

<p>True (A)</p> Signup and view all the answers

The major drawback to polymorphically designed programs is that they do not take into account the future addition or deletion of classes.

<p>False (B)</p> Signup and view all the answers

During what process does polymorphism allow for specifics to be dealt with?

<p>execution</p> Signup and view all the answers

What does polymorphism involve?

<p>the same message sent to a variety of objects, which each interpret in their own way</p> Signup and view all the answers

Polymorphism allows the addition of classes providing they were at least considered during program development.

<p>False (B)</p> Signup and view all the answers

When a request is made to use a derived-class-object method through a base-class reference, C# polymorphically chooses the correct overridden method in the appropriate derived class that's associated with the object.

<p>True (A)</p> Signup and view all the answers

Polymorphism allows you to command a wide variety of objects even if you do not know the objects' types.

<p>True (A)</p> Signup and view all the answers

Polymorphism helps promote software extensibility.

<p>True (A)</p> Signup and view all the answers

What best describes the relationship between base class and derived class types?

<p>A derived class reference can be assigned to a base class variable, but a base class reference cannot be assigned to a derived class variable.</p> Signup and view all the answers

If an app needs to perform a derived-class-specific operation on a derived class object referenced by a base class variable, the app must first cast the base class reference to a derived class reference through a technique known as _________.

<p>downcasting</p> Signup and view all the answers

If a derived class reference is assigned to a base class variable, the variable must be cast back to the derived class before any derived class methods can be called with it.

<p>True (A)</p> Signup and view all the answers

What may not be instantiated?

<p>abstract classes</p> Signup and view all the answers

The abstract methods and properties of a class do not provide an implementation.

<p>True (A)</p> Signup and view all the answers

Concrete classes provide implementations for every method and property they define.

<p>True (A)</p> Signup and view all the answers

You may define implementations for abstract methods to act as default implementations.

<p>False (B)</p> Signup and view all the answers

All methods in an abstract class are inherently abstract.

<p>False (B)</p> Signup and view all the answers

An abstract base class can be used to declare references.

<p>True (A)</p> Signup and view all the answers

The abstract keyword has the same effect as the virtual keyword.

<p>False (B)</p> Signup and view all the answers

An abstract class may be derived from another abstract class.

<p>True (A)</p> Signup and view all the answers

Objects of abstract base classes can be instantiated.

<p>False (B)</p> Signup and view all the answers

Study Notes

Polymorphism Overview

  • Polymorphism allows programming in a generalized manner, enabling flexibility in handling various classes.
  • It facilitates the use of different related classes generically, enhancing code extensibility.
  • The addition of new classes can be achieved with minimal changes to the existing program architecture.

Interfaces

  • An interface defines a collection of methods that must be implemented without providing default implementations.
  • Incorrectly, it is believed interfaces provide default implementations for methods.

True/False Statements

  • Polymorphism enables classes to be added with little or no modifications to existing code: True.
  • While polymorphism aims to be adaptive, certain parts may require changes when the new class directly interacts with existing logic: False.
  • Polymorphic programming simplifies adding new capabilities: True.
  • Polymorphism allows objects from different classes in the same hierarchy to be processed without needing to know the specific class type: True.

Execution and Message Handling

  • The specifics of class behaviors are resolved during program execution.
  • A single message can be sent to various objects, each interpreting the message based on its class-specific logic.

Base and Derived Classes

  • A reference of a derived class can be assigned to a base class variable; the reverse is not true.
  • When needing to call derived class methods with a base class reference, it must first be downcast to the appropriate derived class type.

Abstract Classes

  • Abstract classes cannot be instantiated directly and are typically used as base classes.
  • They can contain abstract methods that do not have implementations, unlike concrete classes that fully implement methods.
  • It is syntax error to provide implementations for abstract methods, reinforcing that they are meant to be overridden in subclasses.

Key Characteristics

  • Not all methods in an abstract class are abstract; some may be concrete with implemented functionality.
  • Abstract classes can be effectively utilized for declaring references, allowing flexibility in method calls.
  • The abstract and virtual keywords serve distinct roles: abstract methods require overrides, while virtual methods provide default implementations.

General Insights

  • Polymorphic programming enhances software extensibility and adaptability, supporting future class additions seamlessly.
  • The relationship between base and derived classes is crucial for polymorphic behavior, enabling a flexible programming environment.

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Description

Test your understanding of polymorphism and interfaces in programming with this quiz. Explore key concepts and true/false statements to reinforce your knowledge about code extensibility and the role of interfaces. Perfect for students looking to grasp object-oriented programming principles.

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