Question 1

Which of the following statements is false?

Accepted Answer

A)  References to interface types do not have access to method toString. 
B)  Method toString can be invoked implicitly on any object. 
C)  With inheritance, classes and their inherited classes tend to be very similar. 
D)  Dramatically different classes can often meaningfully implement the same interface. 
A)  References to interface types do not have access to method toString. 
B)  Method toString can be invoked implicitly on any object. 
C)  With inheritance, classes and their inherited classes tend to be very similar. 
D)  Dramatically different classes can often meaningfully implement the same interface. C

Question 2

Non-abstract classes are called ________.

Accepted Answer

A)  real classes. 
B)  instance classes. 
C)  implementable classes. 
D)  concrete classes. 
A)  real classes. 
B)  instance classes. 
C)  implementable classes. 
D)  concrete classes. D

Question 3

Which of the following statements about abstract superclasses is true?

Accepted Answer

A)  abstract superclasses may contain data. 
B)  abstract superclasses may not contain implementations of methods. 
C)  abstract superclasses must declare all methods as abstract. 
D)  abstract superclasses must declare all data members not given values as abstract. 
A)  abstract superclasses may contain data. 
B)  abstract superclasses may not contain implementations of methods. 
C)  abstract superclasses must declare all methods as abstract. 
D)  abstract superclasses must declare all data members not given values as abstract. A

Question 4

Which keyword is used to specify that a class will define the methods of an interface?

Accepted Answer

A)  uses 
B)  implements 
C)  defines 
D)  extends 
A)  uses 
B)  implements 
C)  defines 
D)  extends

Question 5

It is a UML convention to denote the name of an abstract class in ________.

Accepted Answer

A)  bold. 
B)  italics. 
C)  a diamond. 
D)  there is no convention of the UML to denote abstract classes-they are listed just as any other class. 
A)  bold. 
B)  italics. 
C)  a diamond. 
D)  there is no convention of the UML to denote abstract classes-they are listed just as any other class.

Question 6

When a superclass variable refers to a subclass object and a method is called on that object, the proper implementation is determined at execution time. What is the process of determining the correct method to call?

Accepted Answer

A)  early binding. 
B)  non-binding. 
C)  on-time binding. 
D)  late binding. 
A)  early binding. 
B)  non-binding. 
C)  on-time binding. 
D)  late binding.

Question 7

Which of the following statements is false?

Accepted Answer

A)  You cannot prevent client code from creating objects of a class. 
B)  One common use of a private constructor is sharing initialization code among a class's other constructors. 
C)  Another common use of private constructors is to force client code to use so-called "factory methods" to create objects. 
D)  A factory method is a public static method that creates and initializes an object of a specified type (possibly of the same class), then returns a reference to it. 
A)  You cannot prevent client code from creating objects of a class. 
B)  One common use of a private constructor is sharing initialization code among a class's other constructors. 
C)  Another common use of private constructors is to force client code to use so-called "factory methods" to create objects. 
D)  A factory method is a public static method that creates and initializes an object of a specified type (possibly of the same class), then returns a reference to it.

Question 8

Which of the following statements is false?

Accepted Answer

A)  An advantage of inheritance over interfaces is that only inheritance provides the is-a relationship. 
B)  Objects of any subclass of a class that implements an interface can also be thought of as objects of that interface type. 
C)  When a method parameter is declared with a subclass or interface type, the method processes the object passed as an argument polymorphically. 
D)  All objects have the methods of class Object. 
A)  An advantage of inheritance over interfaces is that only inheritance provides the is-a relationship. 
B)  Objects of any subclass of a class that implements an interface can also be thought of as objects of that interface type. 
C)  When a method parameter is declared with a subclass or interface type, the method processes the object passed as an argument polymorphically. 
D)  All objects have the methods of class Object.

Question 9

A(n)_______class cannot be instantiated.

Accepted Answer

A)  final. 
B)  concrete. 
C)  abstract. 
D)  polymorphic. 
A)  final. 
B)  concrete. 
C)  abstract. 
D)  polymorphic.

Question 10

Which of the following is false?

Accepted Answer

A)  You should not call overridable methods from constructors-when creating a subclass object, this could lead to an overridden method being called before the subclass object is fully initialized. 
B)  It's OK to any of a class's methods from its constructors. 
C)  When you construct a subclass object, its constructor first calls one of the direct superclass's constructors. If the superclass constructor calls an overridable method, the subclass's version of that method will be called by the superclass constructor. 
D)  It's acceptable to call a static method from a constructor. 
A)  You should not call overridable methods from constructors-when creating a subclass object, this could lead to an overridden method being called before the subclass object is fully initialized. 
B)  It's OK to any of a class's methods from its constructors. 
C)  When you construct a subclass object, its constructor first calls one of the direct superclass's constructors. If the superclass constructor calls an overridable method, the subclass's version of that method will be called by the superclass constructor. 
D)  It's acceptable to call a static method from a constructor.

Question 11

Which of the following statements is false?

Accepted Answer

A)  Prior to Java SE 8, it was common to associate with an interface a class containing static helper methods for working with objects that implemented the interface. 
B)  Class Collections contains many static helper methods for working with objects that implement interfaces Collection, List, Set and more. 
C)  Collections method sort can sort objects of any class that implements interface List. 
D)  With non-static interface methods, helper methods can now be declared directly in interfaces rather than in separate classes. 
A)  Prior to Java SE 8, it was common to associate with an interface a class containing static helper methods for working with objects that implemented the interface. 
B)  Class Collections contains many static helper methods for working with objects that implement interfaces Collection, List, Set and more. 
C)  Collections method sort can sort objects of any class that implements interface List. 
D)  With non-static interface methods, helper methods can now be declared directly in interfaces rather than in separate classes.

Question 12

Which of the following statements is false?

Accepted Answer

A)  In Java SE 8, an interface may declare default methods-that is, public methods with concrete implementations that specify how an operation should be performed. 
B)  When a class implements an interface, the class receives the interface's default concrete implementations if it does not override them. 
C)  When you enhance an existing interface with default methods-any class that implemented the original interface will break. 
D)  With default methods, you can declare common method implementations in interfaces (rather than abstract classes), which gives you more flexibility in designing your classes. 
A)  In Java SE 8, an interface may declare default methods-that is, public methods with concrete implementations that specify how an operation should be performed. 
B)  When a class implements an interface, the class receives the interface's default concrete implementations if it does not override them. 
C)  When you enhance an existing interface with default methods-any class that implemented the original interface will break. 
D)  With default methods, you can declare common method implementations in interfaces (rather than abstract classes), which gives you more flexibility in designing your classes.

Question 13

Classes and methods are declared final for all but the following reasons:

Accepted Answer

A)  final methods allow inlining the code. 
B)  final methods and classes prevent further inheritance. 
C)  final methods are static. 
D)  final methods can improve performance. 
A)  final methods allow inlining the code. 
B)  final methods and classes prevent further inheritance. 
C)  final methods are static. 
D)  final methods can improve performance.

Question 14

Consider classes A, B and C, where A is an abstract superclass, B is a concrete class that inherits from A and C is a concrete class that inherits from B. Class A declares abstract method originalMethod, implemented in class B. Which of the following statements is true of class C?

Accepted Answer

A)  Method originalMethod cannot be overridden in class C-once it has been implemented in concrete class B, it is implicitly final. 
B)  Method originalMethod must be overridden in class C, or a compilation error will occur. 
C)  If method originalMethod is not overridden in class C but is called by an object of class C, an error occurs. 
D)  None of the above. 
A)  Method originalMethod cannot be overridden in class C-once it has been implemented in concrete class B, it is implicitly final. 
B)  Method originalMethod must be overridden in class C, or a compilation error will occur. 
C)  If method originalMethod is not overridden in class C but is called by an object of class C, an error occurs. 
D)  None of the above.

Question 15

For which of the following would polymorphism not provide a clean solution?

Accepted Answer

A)  A billing program where there is a variety of client types that are billed with different fee structures. 
B)  A maintenance log program where data for a variety of types of machines is collected and maintenance schedules are produced for each machine based on the data collected. 
C)  A program to compute a 5% savings account interest for a variety of clients. 
D)  An IRS program that maintains information on a variety of taxpayers and determines who to audit based on criteria for classes of taxpayers. 
A)  A billing program where there is a variety of client types that are billed with different fee structures. 
B)  A maintenance log program where data for a variety of types of machines is collected and maintenance schedules are produced for each machine based on the data collected. 
C)  A program to compute a 5% savings account interest for a variety of clients. 
D)  An IRS program that maintains information on a variety of taxpayers and determines who to audit based on criteria for classes of taxpayers.

Question 16

Which statement best describes the relationship between superclass and subclass types?

Accepted Answer

A)  A subclass reference cannot be assigned to a superclass variable and a superclass reference cannot be assigned to a subclass variable. 
B)  A subclass reference can be assigned to a superclass variable and a superclass reference can be assigned to a subclass variable. 
C)  A superclass reference can be assigned to a subclass variable, but a subclass reference cannot be assigned to a superclass variable. 
D)  A subclass reference can be assigned to a superclass variable, but a superclass reference cannot be assigned to a subclass variable. 
A)  A subclass reference cannot be assigned to a superclass variable and a superclass reference cannot be assigned to a subclass variable. 
B)  A subclass reference can be assigned to a superclass variable and a superclass reference can be assigned to a subclass variable. 
C)  A superclass reference can be assigned to a subclass variable, but a subclass reference cannot be assigned to a superclass variable. 
D)  A subclass reference can be assigned to a superclass variable, but a superclass reference cannot be assigned to a subclass variable.

Question 17

If the superclass contains only abstract method declarations, the superclass is used for ________.

Accepted Answer

A)  implementation inheritance. 
B)  interface inheritance. 
C)  Both. 
D)  Neither. 
A)  implementation inheritance. 
B)  interface inheritance. 
C)  Both. 
D)  Neither.

Question 18

Which of the following is not possible?

Accepted Answer

A)  A class that implements two interfaces. 
B)  A class that inherits from two classes. 
C)  A class that inherits from one class, and implements an interface. 
D)  All of the above are possible. 
A)  A class that implements two interfaces. 
B)  A class that inherits from two classes. 
C)  A class that inherits from one class, and implements an interface. 
D)  All of the above are possible.

Question 19

Which of the following statements is false?

Accepted Answer

A)  As of Java SE 8, any interface containing only one method is known as a functional interface. 
B)  There are many functional interfaces throughout the Java APIs. 
C)  Functional interfaces are used extensively with Java SE 8's new lambda capabilities. 
D)  Anonymous methods provide a shorthand notation for creating lambdas. 
A)  As of Java SE 8, any interface containing only one method is known as a functional interface. 
B)  There are many functional interfaces throughout the Java APIs. 
C)  Functional interfaces are used extensively with Java SE 8's new lambda capabilities. 
D)  Anonymous methods provide a shorthand notation for creating lambdas.

Question 20

In Java SE 7 and earlier, an interface may contain:

Accepted Answer

A)  private static data and public abstract methods. 
B)  only public abstract methods. 
C)  public static final data and public abstract methods. 
D)  private static data and public final methods. 
A)  private static data and public abstract methods. 
B)  only public abstract methods. 
C)  public static final data and public abstract methods. 
D)  private static data and public final methods.

Exam 10: Object-Oriented Programming: Polymorphism and Interfaces

Which of the following statements is false?

Non-abstract classes are called ________.

Which of the following statements about abstract superclasses is true?

Which keyword is used to specify that a class will define the methods of an interface?

It is a UML convention to denote the name of an abstract class in ________.

When a superclass variable refers to a subclass object and a method is called on that object, the proper implementation is determined at execution time. What is the process of determining the correct method to call?

Which of the following statements is false?

Which of the following statements is false?

A(n)_______class cannot be instantiated.

Which of the following is false?

Which of the following statements is false?

Which of the following statements is false?

Classes and methods are declared final for all but the following reasons:

Consider classes A, B and C, where A is an abstract superclass, B is a concrete class that inherits from A and C is a concrete class that inherits from B. Class A declares abstract method originalMethod, implemented in class B. Which of the following statements is true of class C?

For which of the following would polymorphism not provide a clean solution?

Which statement best describes the relationship between superclass and subclass types?

If the superclass contains only abstract method declarations, the superclass is used for ________.

Which of the following is not possible?

Which of the following statements is false?

In Java SE 7 and earlier, an interface may contain:

Introduction to Computers, the Internet and Java

Introduction to Java Applications; Inputoutput and Operators

Introduction to Classes, Objects, Methods and Strings

Control Statements: Assignment, and Operators

Control Statements: Logical Operators

Methods: a Deeper Look

Arrays and Arraylists

Classes and Objects: a Deeper Look

Object-Oriented Programming: Inheritance

Exception Handling: a Deeper Look

Javafx Graphical User Interfaces

Javafx Gui

Strings, Characters and Regular Expressions

Files, Inputoutput Streams, Nio and Xml Serialization

Generic Collections

Lambdas and Streams

Recursion

Searching, Sorting and Big O

Generic Classes and Methods: a Deeper Look

Custom Generic Data Structures

Concurrency

Accessing Databases With Jdbc

Swing Gui Components

Graphics and Java 2d

Networking

Java Persistence Api Jpa

Javaserver Faces Web Apps

Javaserver Faces Web Apps

Swing Gui Components

Filters