Deck 11: Object-Oriented Programming: Inheritance

Question 1

Which of the following pairs demonstrates the has-a relationship between the first and the second terms

A) car, vehicle
B) house, window
C) teacher, person
D) None of the above

Answer 1

B

Question 2

Inheritance is the process of building a class with object references of other classes.

Answer 2

False
Inheritance is the process of taking a class and extending its behaviors and capabilities.Building a class from preexisting object references is known as composition.

Question 3

A derived class cannot access the members of its base class.

A) private
B) static
C) protected
D) None of the above.

Answer 3

A

Question 4

Constructors are not inherited.

Question 5

Inheritance is represented by a(n)________ relationship.

A) "uses"
B) "is-a"
C) "has-a"
D) None of the above.

Question 6

An object of one class cannot be an object of another class.

Question 7

Identify which of the following examples could be considered a base class for the Computer class

A) machine
B) hard-drive
C) software
D) keyboard

Question 8

A class inherited from two or more levels up in the hierarchy is known as a

A) indirect base class
B) direct base class
C) superclass
D) None of the above

Question 9

Which of the following is not a base/derived class relationship

A) Ford/Taurus
B) University/Boston University
C) Sailboat/Tugboat
D) Country/USA

Question 10

A derived class can effect state changes in base class private members only through public,protected,internal methods provided in the base class and inher
ited into the derived class.

Question 11

A base class may have only one derived class.

Question 12

Which of the following pairs demonstrates the is-a relationship between the first and the second terms

A) car, engine
B) book, table of contents
C) baseball, sport
D) None of the above

Question 13

An advantage of inheritance is that:

A) all methods can be inherited
B) all instance variables can be uniformly accessed by base classes and derived classes
C) Objects of a derived class can be treated like objects of their base class
D) None of the above.

Question 14

A class that inherits from another class is referred to as the derived class.

Question 15

A derived class is often larger and more general than its base class.

Question 16

The process of abstraction allows you to focus on the commonalities among objects in the system.

Question 17

Members of a base class that are private are not inherited by derived classes.

Question 18

Every object of a base class is an object of that class's derived classes.

Question 19

Multiple inheritance,widely used in C#,is the process of inheriting from more than one class.

Question 20

All classes in C# have object as either a direct or indirect base class.

Question 21

Which base class members are inherited by all derived classes of that base class

A) private instance variables and methods
B) protected instance variables and methods
C) private constructors
D) protected constructors

Question 22

Base class methods with this level of access cannot be called from derived classes.

A) private
B) public
C) protected
D) package

Question 23

Consider the classes below,declared in the same file:
Class A
{
Int a;
Public A()
{
A = 7;
}
}
Class B : A
{
Int b;
Public B()
{
B = 8;
}
}
Which of the statements below is false

A) Both variables a and b are instance variables.
B) After the constructor for class B is executed, the variable a will have the value 7.
C) After the constructor for class B is executed, the variable b will have the value 8.
D) A reference to class A can be treated as a reference to class B.

Question 24

To avoid duplicating code (and possibly errors),use ________,rather than ________.

A) inheritance, the "copy-and-paste" approach.
B) the "copy-and-past" approach, inheritance.
C) a class that explicitly extends object, a class that does not extend object. d. a class that does not extend object, a class that explicitly extends object.

Question 25

Which of the following classes is the root of the class hierarchy

A) object
B) Point
C) ToString
D) None of the above

Question 26

The protected members of a class may be accessed in their base class or any classes derived from that base class.

Question 27

Overriding a method differs from overloading a constructor because:

A) For an overloaded constructor, the base class constructor will always be called first.
B) For an overridden constructor, the base class constructor will always be called first.
C) Overloaded methods have the same signature.
D) Overridden methods have the same signature.

Question 28

When a derived class constructor calls its base class constructor,what happens if the base class's constructor does not assign a value to an instance variable

A) a syntax error occurs
B) a compile-time error occurs
C) a run-time error occurs
D) the program compiles and runs correctly because the instance variables are initialized to their default values

Question 29

How can a derived class call a base class constructor

A)implicitly
B) explicitly
C) a and b
D) the derived class cannot call the base class constructor

Question 30

Every class in C#,except __________,extends an existing class.

A) Integer
B) object
C) String
D) Class

Question 31

When a program creates a derived-class object,the object constructor is the last constructor called and the first whose body finishes executing.

Question 32

A base class's constructors are inherited into its derived classes.

Question 33

When a derived-class member overrides a base-class member,the base-class member can be accessed from the derived-class by using the keyword

A) base
B) top
C) super
D) None of the above

Question 34

A method must be declared
__________ for it to be overridden by derived classes.

A) overrides
B) overridable
C) virtual
D) None of the above

Question 35

Using protected instance variables can cause derived-class methods to be written to depend on base-class implementation.

Question 36

A "copy-and-paste" approach is a simple and efficient way from a software-engineering perspective of providing func
tionality that exists in other classes.

Question 37

private fields of a base class can be accessed in a derived class

A) by calling private methods declared in the base class
B) by calling public or protected methods declared in the base class
C) directly
D) All of the above

Question 38

The first task of any derived-class constructor is to call its base-class con
structor.

Question 39

Which statement is true when a base class has protected instance variables

A) A derived class object can assign an invalid value to the base class's instance variables, thus leaving the object in an inconsistent state.
B) Derived class methods are more likely to be written so that they depend on the base class's data implementation.
C) We may need to modify all the derived classes of the base class if the base class implementation changes.
D) All of the above.

Question 40

Derived classes provide the functionality and features inherited by base classes.

Question 41

A base class is often designed by factoring out commonalities among a set of classes.

Question 42

When creating derived classes,you must use discretion in choosing the proper base class.Ideally,the base class will not contain excessive capabilities or information.

Question 43

If a base class constructor is overridden,the original constructor can no longer be called explicitly by the derived class.

Question 44

Which of the following statements is (are)true
A)We can use inheritance to customize existing software.
B)A base class specifies commonality.
C)A base class can be modified without modifying derived classes
D)A derived class can be modified without modifying its derived class.

A) All of the above
B) None of the above
C) A, B and C
D) A, B and D

Question 45

Inheritance preserves the integrity of a base class.

Question 46

When a base class method is overridden in a derived class,it is common to have the derived
class version call the base class version and do some additional work.

Question 47

Method Equals will accurately compare any two objects.

Question 48

To enhance performance and reduce errors,it's a good idea to make derived classes larger than they need to be.

Question 49

The default Equals implementation determines:

A) whether two references refer to the same object in memory.
B) whether two references have the same type.
C) whether two objects have the same instance variables.
D) whether two objects have the same instance variable values.

Question 50

A key to improving the software development process is encouraging soft
ware reuse.

Question 51

The default implementation of method ToString of object returns a string representing ________.

A) the object's type
B) the object class name
C) namespace_name.object_class_name
D) None of the above