Deck 17: Object-Oriented Design

Question 1

An abstraction hides details. A good abstraction hides the right details at the right time so that we can manage __________.

A) Capacity
B) Time
C) Complexity
D) None of the above

Answer 1

Complexity

Question 2

Each _______ clause on a try statement handles a particular kind of exception that may be thrown within the try block.

A) Catch
B) Exception
C) Throw
D) None of the above

Answer 2

Catch

Question 3

The versions of an overloaded method are distinguished by their ___________. The number, type, or order of their parameters must be distinct.

A) Signatures
B) Headers
C) Documentation
D) None of the above

Answer 3

Signatures

Question 4

A _______ is a blueprint for an object; it reserves no memory space for data. Each object has its own data space, and thus its own state.

A) Class
B) Object
C) UML
D) None of the above

Question 5

The ________ of a variable, which determines where it can be referenced, depends on where it is declared.

A) Type
B) Value
C) Scope
D) None of the above

Question 6

Several references can refer to the same object. These references are ________ of each other.

A) Copies
B) Aliases
C) Siblings
D) None of the above

Question 7

The toString and equals methods are defined in the Object class and therefore are ________ by every class in every Java program.

A) Inherited
B) Copied
C) Ignored
D) None of the above

Question 8

Visibility modifiers determine which variables and methods are inherited. ___________ visibility provides the best possible encapsulation that permits inheritance.

A) Public
B) Private
C) Protected
D) None of the above

Question 9

A child class can _________ (redefine) the parent's definition of an inherited method.

A) Override
B) Overload
C) Implement
D) None of the above

Question 10

A class derived from an abstract parent must __________ all of its parent's abstract methods, or the derived class will also be considered abstract.

A) Use
B) Copy
C) Override
D) Overload

Question 11

A reference variable can refer to any object created from any class related to it by ___________.

A) Reference
B) Value
C) Inheritance
D) None of the above

Question 12

A ______ is a Java language element used to group related classes under a common name.

Question 13

Each object has a ____ and a set of ____.

Question 14

An object reference variable stores the ______ of an object.

Question 15

The reserved word ______ represents a reference that does not point to a valid object.

Question 16

A variable declared in a method is ______ to that method and cannot be used outside of it.

Question 17

The ______ operator compares object references for equality, returning true if the references are aliases of each other.

Question 18

The ______ method can be defined to determine equality between objects in any way we consider appropriate.

Question 19

If an object has no references to it, a program cannot use it. Java performs ______ by periodically reclaiming the memory space occupied by these objects.

Question 20

A ______ class represents a primitive value so that it can be treated as an object.

Question 21

A parent's constructor can be invoked using the ______ reference.

Question 22

The child of one class can be the parent of one or more other classes, creating a class ______.

Question 23

All Java classes are derived, directly or indirectly, from the ______ class.

Question 24

An ______ class cannot be instantiated. It represents a concept on which other classes can build their definitions.

Question 25

A ______ reference can refer to different types of objects over time.

Question 26

Interfaces allow us to make ______ references, in which the method that is invoked is based on the particular object being referenced at the time.

Question 27

The messages printed by a thrown exception indicate the nature of the problem and provide a ______.

Question 28

If an exception is not caught and handled where it occurs, it is ______ to the calling method.

Question 29

The new operator returns a reference to a newly created object.

Question 30

The values of an object's variables define its behavior. The methods to which an object responds define its state.

Question 31

Objects should be encapsulated. The rest of a program should interact with an object only through a well-defined interface.

Question 32

Instance variables should be declared with public visibility to promote encapsulation.

Question 33

A constructor cannot have any return type, even void.

Question 34

The this reference always refers to the currently executing object.

Question 35

When an object is passed to a method, the actual and formal parameters become aliases of each other.

Question 36

A method is made static by using the static modifier in the method
declaration.

Question 37

Inherited variables and methods can be used in the derived class as if they had been declared locally.

Question 38

An interface is a collection of abstract methods. It cannot be instantiated.

Question 39

Common features should be located as low in a class hierarchy as is reasonable, minimizing maintenance efforts.

Question 40

Inheritance can be applied to interfaces, so that one interface can be derived from another interface.

Question 41

A polymorphic reference uses the type of the reference, not the type of the object, to determine which version of a method to invoke.

Question 42

Errors and exceptions represent unusual or invalid processing.

Question 43

Objects should be self-governing. Explain.

Question 44

Describe each of the following:
a. public method
b. private method
c. public variable
d. private variable

Question 45

What are constructors used for? How are they defined?

Question 46

How are overloaded methods distinguished from each other?

Question 47

What is an aggregate object?

Question 48

What is the difference between a static variable and an instance variable?

Question 49

What is the difference between a class and an interface?

Question 50

Describe the relationship between a parent class and a child class.

Question 51

What relationship should every class derivation represent?

Question 52

What is the significance of the Object class?

Question 53

How is overriding related to polymorphism?

Question 54

How can polymorphism be accomplished using interfaces?