Question 1

Which of the following statements is false?

Accepted Answer

A)  A class can directly inherit from class Object.
B)  It's often much more efficient to create a class by inheriting from a similar class than to create the class by writing every line of code the new class requires.
C)  If the class you're inheriting from declares instance variables as private,the inherited class can access those instance variables directly.
D)  A class's instance variables are normally declared private to enforce good software engineering.

Question 2

Using the protected keyword also gives a member:

Accepted Answer

A)  public access.
B)  package access.
C)  private access.
D)  block scope.

Question 3

The default equals implementation of class Object determines:

Accepted Answer

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 4

Which of the following is the superclass constructor call syntax?

Accepted Answer

A)  keyword super,followed by a dot (. ) .
B)  keyword super,followed by a set of parentheses containing the superclass constructor arguments.
C)  keyword super,followed by a dot and the superclass constructor name.
D)  None of the above.

Question 5

Private fields of a superclass can be accessed in a subclass

Accepted Answer

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

Question 6

An advantage of inheritance is that:

Accepted Answer

A)  All methods can be inherited.
B)  All instance variables can be uniformly accessed by subclasses and superclasses.
C)  Objects of a subclass can be treated like objects of their superclass.
D)  None of the above.

Question 7

When overriding a superclass method and calling the superclass version from the subclass method,failure to prefix the superclass method name with the keyword super and a dot (.) in the superclass method call causes ________.

Accepted Answer

A)  a compile-time error.
B)  a syntax error.
C)  infinite recursion.
D)  a runtime error. C

Question 8

Which of the following is not a superclass/subclass relationship?

Accepted Answer

A)  Employee/Hourly Employee.
B)  Vehicle/Car.
C)  Sailboat/Tugboat.
D)  None of the above. C

Question 9

Superclass methods with this level of access cannot be called from subclasses.

Accepted Answer

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

Question 10

Which of the following keywords allows a subclass to access a superclass method even when the subclass has overridden the superclass method?

Accepted Answer

A)  base.
B)  this.
C)  public.
D)  super.

Question 11

Which method changes the text the label displays?

Accepted Answer

A)  changeText.
B)  setText.
C)  changeLabel.
D)  setLabel.

Question 12

To avoid duplicating code,use ________,rather than ________.

Accepted Answer

A)  inheritance,the "copy-and-past" approach.
B)  the "copy-and-paste" 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 13

Class ________ represents an image that can be displayed on a JLabel.

Accepted Answer

A)  Image.
B)  Icon.
C)  ImageIcon.
D)  IconImage.

Question 14

Inheritance is also known as the

Accepted Answer

A)  knows-a relationship.
B)  has-a relationship.
C)  uses-a relationship.
D)  is-a relationship.

Question 15

Which of the following statements is false?

Accepted Answer

A)  A subclass is often larger than its superclass.
B)  A superclass object is a subclass object.
C)  The class following the extends keyword in a class declaration is the direct superclass of the class being declared.
D)  Java uses interfaces to provide the benefits of multiple inheritance.

Question 16

The default implementation of method clone of Object performs a ________.

Accepted Answer

A)  empty copy.
B)  deep copy.
C)  full copy.
D)  shallow copy.

Question 17

Every class in Java,except ________,extends an existing class.

Accepted Answer

A)  Integer.
B)  Object.
C)  String.
D)  Class.

Question 18

When a subclass constructor calls its superclass constructor,what happens if the superclass's constructor does not assign a value to an instance variable?

Accepted Answer

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

Question 19

Overriding a method differs from overloading a method because:

Accepted Answer

A)  Overloaded methods have the same signature.
B)  Overridden methods have the same signature.
C)  Both of the above.
D)  Neither of the above.

Question 20

Which superclass members are inherited by all subclasses of that superclass?

Accepted Answer

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

Exam 9: Object Oriented Programming: Inheritance

Which of the following statements is false?

Correct AnswerverifiedShow Answer

Using the protected keyword also gives a member:

Correct AnswerverifiedShow Answer

The default equals implementation of class Object determines:

Correct AnswerverifiedShow Answer

Which of the following is the superclass constructor call syntax?

Correct AnswerverifiedShow Answer

Private fields of a superclass can be accessed in a subclass

Correct AnswerverifiedShow Answer

An advantage of inheritance is that:

Correct AnswerverifiedShow Answer

When overriding a superclass method and calling the superclass version from the subclass method,failure to prefix the superclass method name with the keyword super and a dot (.) in the superclass method call causes ________.

Correct AnswerverifiedC

Which of the following is not a superclass/subclass relationship?

Correct AnswerverifiedC

Superclass methods with this level of access cannot be called from subclasses.

Correct AnswerverifiedShow Answer

Which of the following keywords allows a subclass to access a superclass method even when the subclass has overridden the superclass method?

Correct AnswerverifiedShow Answer

Which method changes the text the label displays?

Correct AnswerverifiedShow Answer

To avoid duplicating code,use ________,rather than ________.

Correct AnswerverifiedShow Answer

Class ________ represents an image that can be displayed on a JLabel.

Correct AnswerverifiedShow Answer

Inheritance is also known as the

Correct AnswerverifiedShow Answer

Which of the following statements is false?

Correct AnswerverifiedShow Answer

The default implementation of method clone of Object performs a ________.

Correct AnswerverifiedShow Answer

Every class in Java,except ________,extends an existing class.

Correct AnswerverifiedShow Answer

When a subclass constructor calls its superclass constructor,what happens if the superclass's constructor does not assign a value to an instance variable?

Correct AnswerverifiedD

Overriding a method differs from overloading a method because:

Correct AnswerverifiedShow Answer

Which superclass members are inherited by all subclasses of that superclass?

Correct AnswerverifiedShow Answer

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C

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C

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To avoid duplicating code,use ,rather than .

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D

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