Deck 11: Classes Continued

Question 1

If a class implements an interface, all its subclasses do so implicitly.

Answer 1

True

Question 2

Characteristics common to several classes can be collected in a common abstract subclass. ____________________

Answer 2

False

Question 3

A class variable belongs to an object and is allocated storage when the object is created.

Answer 3

False

Question 4

Interfaces can be organized in an inheritance hierarchy.

Question 5

Classes that are related by inheritance have a has-a relationship. ____________________

Question 6

When you declare a variable, it should have a different interface name from the type name.

Question 7

An abstract class is one that will not be instantiated. ____________________

Question 8

Class methods can reference only instance variables, never static variables.

Question 9

It is easier to maintain a program that uses interface types.

Question 10

A Java ____ specifies the set of methods available to clients of a class.

A) interface
B) alias
C) variable
D) exception

Question 11

The methods in an interface are usually private. ____________________

Question 12

____ is when methods in different classes with a similar function are given the same name.

A) Aliasing
B) Inheritance
C) Polymorphism
D) Referencing

Question 13

The value of a class constant is assigned ____.

A) during execution
B) based on user input
C) based on inheritance
D) when the variable is declared

Question 14

A class can implement methods in addition to those listed in the interface.

Question 15

An interface is a class.

Question 16

A subclass often has methods that do not appear in its superclass.

Question 17

A class method is activated when a message is sent to the class rather than the object. ____________________

Question 18

____ provides a mechanism for reusing code and can reduce the effort required to implement a new class.

A) Aliasing
B) Inheritance
C) Polymorphism
D) Referencing

Question 19

In general, a static variable is used in any situation in which all instances share a common data value.

Question 20

In the TurtleGraphics package, the pen is initially all of the following EXCEPT ____.

A) at position [0,0]
B) ready to draw a square
C) pointing north
D) in the down position

Question 21

To compare objects for equality, use the ____.

A) = = operator
B) equals method
C) compare operator
D) both a and b are true.

Question 22

The class immediately above another is called its ____.

A) superclass
B) subclass
C) descendent
D) root

Question 23

The most general type of array is one whose element type is ____.

A) String
B) Object
C) Shape
D) Int

Question 24

____ a variable to a type that conflicts with its true identity leads to a run-time error.

A) Defining
B) Assigning
C) Declaring
D) Casting

Question 25

In Java, all classes are part of an immense hierarchy, with the class ____________________ at the root.

Question 26

A(n) ____________________ class is one that will be instantiated.

Question 27

FIGURE 11-1
Alec suggests that Amara create documentation for her program by embedding comments using the ____ symbol.

A) <
B) @
C) {
D) /**

Question 28

A(n) ____ method is accessible to a class's descendents, but not to any other classes in the hierarchy.

A) protected
B) private
C) dependent
D) inherited

Question 29

FIGURE 11-1
In Figure 11-1 above, we say that AAA ____ Object.

A) aliases
B) extends
C) aggregates
D) overrides

Question 30

When information needs to be shared among all instances of a class, that information can be represented in terms of ____________________ variables.

Question 31

When the element type of an array is a(n) ____ or interface, objects of those types or any subtype can be directly inserted into the array.

A) primitive
B) concrete
C) abstract
D) reference

Question 32

A class's ____ provides the information needed to use the class without revealing anything about its implementation..

A) value
B) definition
C) interface
D) hierarchy

Question 33

One way to enforce preconditions is to ____.

A) use comments
B) declare them
C) use inheritance
D) throw an exception

Question 34

The relationship that allows an object of one class to send a message to an object of another class is called ____.

A) inheritance
B) superclass
C) dependency
D) aggregation

Question 35

A(n) ____________________ method cannot be overridden by a subclass.

Question 36

Methods in a subclass can be related to methods in a superclass in all of the following ways EXCEPT ____.

A) implementation of a concrete method.
B) extension
C) overriding
D) finality

Question 37

FIGURE 11-1
Figure 11-1 above shows an example of a ____ hierarchy.

A) class
B) interface
C) program
D) method

Question 38

The ____ process uses the clone message to obtain copies.

A) duplication
B) deep copying
C) aliasing
D) overriding

Question 39

When related classes have the same ____, they can be used interchangeably in a program.

A) value
B) definition
C) interface
D) hierarchy

Question 40

If more than one class implements an interface, its methods are ____.

A) aggregated
B) public
C) dependent
D) polymorphic

Question 41

Identify the letter of the choice that best matches the phrase or definition.
a.Dependency
b.Extension
c.Overriding
d.Aggregation
e.Inheritance
When an object of one class contains objects of another class as structural components.

Question 42

A method's ____________________ describe what should be true before it is called.

Question 43

Identify the letter of the choice that best matches the phrase or definition.
a.Dependency
b.Extension
c.Overriding
d.Aggregation
e.Inheritance
When objects are related by sending and receiving a message.

Question 44

Identify the letter of the choice that best matches the phrase or definition.
a.Dependency
b.Extension
c.Overriding
d.Aggregation
e.Inheritance
When the subclass method does not exist in the superclass.

Question 45

Identify the letter of the choice that best matches the phrase or definition.
a.Dependency
b.Extension
c.Overriding
d.Aggregation
e.Inheritance
When the subclass method is intended as a replacement of the superclass method.

Question 46

Identify the letter of the choice that best matches the phrase or definition.
a.Dependency
b.Extension
c.Overriding
d.Aggregation
e.Inheritance
When an object's class is a subclass of a more general class.