Question 1

Consider the following code snippet:   Which of the following statements is correct?

Accepted Answer

A) The toString() method of the Object class is being used to set the value of s. 
B) The toString() method of the Integer class is being used to set the value of s. 
C) No toString() method is being used to set the value of s. 
D) This code will not compile. 
A) The toString() method of the Object class is being used to set the value of s. 
B) The toString() method of the Integer class is being used to set the value of s. 
C) No toString() method is being used to set the value of s. 
D) This code will not compile.

Question 2

Suppose the abstract class Message is defined below   A concrete subclass of Message, called FrenchMessage, is defined.Which methods must FrenchMessage define?

Accepted Answer

A) translate() only 
B) getMessage() only 
C) The FrenchMessage constructor and translate() only 
D) The FrenchMessage constructor, getMessage(), and translate() 
A) translate() only 
B) getMessage() only 
C) The FrenchMessage constructor and translate() only 
D) The FrenchMessage constructor, getMessage(), and translate()

Question 3

What reserved word in a method definition ensures that subclasses cannot override the method?

Accepted Answer

A) abstract 
B) anonymous 
C) final 
D) static 
A) abstract 
B) anonymous 
C) final 
D) static

Question 4

Consider the Counter class below.

Accepted Answer

A) true 
B) false 
C) nothing since equals is not defined for Counter 
D) a syntax error 
A) true 
B) false 
C) nothing since equals is not defined for Counter 
D) a syntax error

Question 5

Consider the following code snippet:   What is wrong with this code?

Accepted Answer

A) The return statement should use the == operator instead of the equals method. 
B) The parameter in the equals method should be declared as Score otherScore. 
C) It is an error to cast otherScore as a Score object before using the equals method. 
D) There is nothing wrong with this code. 
A) The return statement should use the == operator instead of the equals method. 
B) The parameter in the equals method should be declared as Score otherScore. 
C) It is an error to cast otherScore as a Score object before using the equals method. 
D) There is nothing wrong with this code.

Question 6

Consider the following code snippet:   What does this code do?

Accepted Answer

A) This code tests whether anObject was created from a superclass of Auto. 
B) This code creates a subclass type object from a superclass type object. 
C) This class safely converts an object of any type to an object of type Auto. 
D) This code safely converts an object of type Auto or a subclass of Auto to an object of type Auto. 
A) This code tests whether anObject was created from a superclass of Auto. 
B) This code creates a subclass type object from a superclass type object. 
C) This class safely converts an object of any type to an object of type Auto. 
D) This code safely converts an object of type Auto or a subclass of Auto to an object of type Auto.

Question 7

Consider the hierarchy of classes shown below.   What is the superclass of the class TelevisionShow?

Accepted Answer

A) Object 
B) Comedy 
C) RealityShow 
D) This class has no superclass 
A) Object 
B) Comedy 
C) RealityShow 
D) This class has no superclass

Question 8

You are creating a class inheritance hierarchy about motor vehicles that will contain classes named Vehicle, Auto, and Motorcycle.Which of the following statements is correct?

Accepted Answer

A) Vehicle should be the default class, 
while Auto and Motorcycle should be the subclasses. 
B) Vehicle should be the superclass, 
while Auto and Motorcycle should be the subclasses. 
C) Vehicle should be the subclass, while Auto and Motorcycle should be the superclasses. 
D) Vehicle should be the subclass, while Auto and Motorcycle should be the default classes. 
A) Vehicle should be the default class, 
while Auto and Motorcycle should be the subclasses. 
B) Vehicle should be the superclass, 
while Auto and Motorcycle should be the subclasses. 
C) Vehicle should be the subclass, while Auto and Motorcycle should be the superclasses. 
D) Vehicle should be the subclass, while Auto and Motorcycle should be the default classes.

Question 9

Consider the following code snippet:   If the Programmer class inherits from the Employee class, and only the Employee class has an implementation of the increaseSalary method, which statement is correct?

Accepted Answer

A) The increaseSalary method call will cause a run-time error. 
B) The increaseSalary method of the Employee class will be executed. 
C) The Programmer class is required to provide an implementation of the increaseSalary method. 
D) Programmer objects must be cast to Employee objects before the method call can me made. 
A) The increaseSalary method call will cause a run-time error. 
B) The increaseSalary method of the Employee class will be executed. 
C) The Programmer class is required to provide an implementation of the increaseSalary method. 
D) Programmer objects must be cast to Employee objects before the method call can me made.

Question 10

Consider the following code snippet:   Assume that the Programmer class inherits from the Employee class, and only the Employee class has an implementation of the toString() method.Which of the following statements is correct?

Accepted Answer

A) The toString() method of the Object class will be used when this code is executed. 
B) The toString() method of the Employee class will be used when this code is executed. 
C) The toString() method of the String class will be used when this code is executed. 
D) This code will not compile because there is no toString() method in the Programmer class. 
A) The toString() method of the Object class will be used when this code is executed. 
B) The toString() method of the Employee class will be used when this code is executed. 
C) The toString() method of the String class will be used when this code is executed. 
D) This code will not compile because there is no toString() method in the Programmer class.

Question 11

What reserved word in a class definition ensures that subclasses cannot be created from the class?

Accepted Answer

A) abstract 
B) anonymous 
C) final 
D) static 
A) abstract 
B) anonymous 
C) final 
D) static

Question 12

Consider the following code snippet:

Accepted Answer

A) The Vehicle class constructor would invoke the constructor of the Motorcycle class with no parameters. 
B) The Motorcycle class constructor would invoke the constructor of the Vehicle class with a parameter value of 0. 
C) The Motorcycle class constructor would invoke the constructor of the Vehicle class with no parameters. 
D) This code would not compile. 
A) The Vehicle class constructor would invoke the constructor of the Motorcycle class with no parameters. 
B) The Motorcycle class constructor would invoke the constructor of the Vehicle class with a parameter value of 0. 
C) The Motorcycle class constructor would invoke the constructor of the Vehicle class with no parameters. 
D) This code would not compile.

Question 13

Consider the following class hierarchy:   Which of the following code fragments is NOT valid in Java?

Accepted Answer

A) Vehicle myAuto = new Auto("sedan"); 
B) LandVehicle myAuto = new Auto("sedan"); 
C) Auto myAuto = new Auto("sedan"); 
D) LandVehicle myAuto = new Vehicle("sedan"); 
A) Vehicle myAuto = new Auto("sedan"); 
B) LandVehicle myAuto = new Auto("sedan"); 
C) Auto myAuto = new Auto("sedan"); 
D) LandVehicle myAuto = new Vehicle("sedan");

Question 14

Consider the following code snippet:
  What is wrong with this code?
A)The return statement should use the == operator instead of the equals method.
B)The parameter in the equals method should be declared as Coin otherCoin.
C)otherCoin must be cast as a Coin object before using the equals method.
D)There is nothing wrong with this code.

Accepted Answer

The answer of Consider the following code snippet:
  What...

Question 15

Consider the classes shown below:

Accepted Answer

A) -14 21 
B) 21 21 
C) 21 100 
D) 100 100 
A) -14 21 
B) 21 21 
C) 21 100 
D) 100 100

Question 16

What is the term used for a subclass that defines a method with the same name as a method in its superclass, but with different parameter types?

Accepted Answer

A) implementing 
B) inheriting 
C) overriding 
D) overloading 
A) implementing 
B) inheriting 
C) overriding 
D) overloading

Question 17

Consider the following code snippet:   Which of the following statements is true?

Accepted Answer

A) This method will call itself. 
B) This method calls a public method in its subclass. 
C) This method calls a private method in its superclass 
D) This method calls a public method in its superclass. 
A) This method will call itself. 
B) This method calls a public method in its subclass. 
C) This method calls a private method in its superclass 
D) This method calls a public method in its superclass.

Question 18

Why is the following code, which assumes ChoiceQuestion is a subclass of Question, considered poor strategy?

Accepted Answer

A) Question should be the subclass, not the other way around. 
B) instanceof is not an operator but rather a method. 
C) instanceof should not be used for type tests that can be solved by using polymorphism. 
D) the instanceof reserved word should only be used in a class constructor. 
A) Question should be the subclass, not the other way around. 
B) instanceof is not an operator but rather a method. 
C) instanceof should not be used for type tests that can be solved by using polymorphism. 
D) the instanceof reserved word should only be used in a class constructor.

Question 19

Consider the classes shown below:

Accepted Answer

A) 100 100 
B) -14 100 
C) -14 -14 
D) 100 -14 
A) 100 100 
B) -14 100 
C) -14 -14 
D) 100 -14

Question 20

Which of the following statements about classes is true?

Accepted Answer

A) You can create an object from a class declared with the keyword final. 
B) You can override methods in a class declared with the keyword final. 
C) You can extend a class declared with the keyword final. 
D) You can create subclasses from a class declared with the keyword final. 
A) You can create an object from a class declared with the keyword final. 
B) You can override methods in a class declared with the keyword final. 
C) You can extend a class declared with the keyword final. 
D) You can create subclasses from a class declared with the keyword final.

Exam 9: Inheritance

Consider the following code snippet: Which of the following statements is correct?

Suppose the abstract class Message is defined below A concrete subclass of Message, called FrenchMessage, is defined.Which methods must FrenchMessage define?

What reserved word in a method definition ensures that subclasses cannot override the method?

Consider the Counter class below.

Consider the following code snippet: What is wrong with this code?

Consider the following code snippet: What does this code do?

Consider the hierarchy of classes shown below. What is the superclass of the class TelevisionShow?

You are creating a class inheritance hierarchy about motor vehicles that will contain classes named Vehicle, Auto, and Motorcycle.Which of the following statements is correct?

Consider the following code snippet: If the Programmer class inherits from the Employee class, and only the Employee class has an implementation of the increaseSalary method, which statement is correct?

Consider the following code snippet: Assume that the Programmer class inherits from the Employee class, and only the Employee class has an implementation of the toString() method.Which of the following statements is correct?

What reserved word in a class definition ensures that subclasses cannot be created from the class?

Consider the following code snippet:

Consider the following class hierarchy: Which of the following code fragments is NOT valid in Java?

Consider the classes shown below:

What is the term used for a subclass that defines a method with the same name as a method in its superclass, but with different parameter types?

Consider the following code snippet: Which of the following statements is true?

Why is the following code, which assumes ChoiceQuestion is a subclass of Question, considered poor strategy?

Consider the classes shown below:

Which of the following statements about classes is true?

Introduction

Using Objects

Implementing Classes

Fundamental Data Types

Decisions

Loops

Arrays and Array Lists

Designing Classes

Interfaces

Input/Output and Exception Handling

Object-Oriented Design

Recursion

Sorting and Searching

The Java Collections Framework

Basic Data Structures

Tree Structures

Generic Classes

Stream Processing

Graphical User Interfaces

Advanced Input/Output

Multithreading

Internet Networking

Relational Databases

XML

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