Question 1

class cannot be instantiated.

Accepted Answer

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

Question 2

Every object in Java knows its own class and can access this information through method .

Accepted Answer

A) getClass. 
B) getInformation. 
C) objectClass. 
D) objectInformation. 
A) getClass. 
B) getInformation. 
C) objectClass. 
D) objectInformation. A

Question 3

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 4

Assigning a subclass reference to a superclass variable is safe:

Accepted Answer

A) because the subclass object has an object of its superclass. 
B) because the subclass object is an object of its superclass. 
C) only when the superclass is abstract. 
D) only when the superclass is concrete. 
A) because the subclass object has an object of its superclass. 
B) because the subclass object is an object of its superclass. 
C) only when the superclass is abstract. 
D) only when the superclass is concrete.

Question 5

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 6

All of the following methods are implicitly final except:

Accepted Answer

A) a method in an abstract class. 
B) a private method. 
C) a method declared in a final class. 
D) static method. 
A) a method in an abstract class. 
B) a private method. 
C) a method declared in a final class. 
D) static method.

Question 7

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 8

Which of the following could be used to declare abstract method method1 in abstract class Class1 (method1 returns an int and takes no arguments)?

Accepted Answer

A) public int method1(); 
B) public int abstract method1(); 
C) public abstract int method1(); 
D) public int nonfinal method1(); 
A) public int method1(); 
B) public int abstract method1(); 
C) public abstract int method1(); 
D) public int nonfinal method1();

Question 9

Polymorphism enables you to:

Accepted Answer

A) program in the general. 
B) program in the specific. 
C) absorb attributes and behavior from previous classes. 
D) hide information from the user. 
A) program in the general. 
B) program in the specific. 
C) absorb attributes and behavior from previous classes. 
D) hide information from the user.

Question 10

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 11

The UML distinguishes an interface from other classes by placing the word "interface" in above the interface name.

Accepted Answer

A) italics. 
B) carets. 
C) guillemets. 
D) bold. 
A) italics. 
B) carets. 
C) guillemets. 
D) bold.

Question 12

Polymorphism allows for specifics to be dealt with during:

Accepted Answer

A) execution. 
B) compilation. 
C) programming. 
D) debugging. 
A) execution. 
B) compilation. 
C) programming. 
D) debugging.

Question 13

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 14

Declaring a method final means:

Accepted Answer

A) it will prepare the object for garbage collection. 
B) it cannot be accessed from outside its class. 
C) it cannot be overloaded. 
D) it cannot be overridden. 
A) it will prepare the object for garbage collection. 
B) it cannot be accessed from outside its class. 
C) it cannot be overloaded. 
D) it cannot be overridden.

Question 15

Which of the following does not complete the sentence correctly? An interface .

Accepted Answer

A) forces classes that implement it to declare all the interface methods. 
B) can be used in place of an abstract class when there is no default implementation to inherit. 
C) is declared in a file by itself and is saved in a file with the same name as the interface followed by the .java extension. 
D) can be instantiated. 
A) forces classes that implement it to declare all the interface methods. 
B) can be used in place of an abstract class when there is no default implementation to inherit. 
C) is declared in a file by itself and is saved in a file with the same name as the interface followed by the .java extension. 
D) can be instantiated.

Question 16

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.

Question 17

Interfaces can have methods.

Accepted Answer

A) 0 
B) 1 
C) 2 
D) any number of 
A) 0 
B) 1 
C) 2 
D) any number of

Question 18

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 19

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 syntax 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 syntax 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 20

A class that implements an interface but does not declare all of the interface's methods must be declared:

Accepted Answer

A) public. 
B) interface. 
C) abstract. 
D) final. 
A) public. 
B) interface. 
C) abstract. 
D) final.

Exam 10: Object-Oriented Programming: Polymorphism

class cannot be instantiated.

Every object in Java knows its own class and can access this information through method .

Non-abstract classes are called:

Assigning a subclass reference to a superclass variable is safe:

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?

All of the following methods are implicitly final except:

Which of the following is not possible?

Which of the following could be used to declare abstract method method1 in abstract class Class1 (method1 returns an int and takes no arguments)?

Polymorphism enables you to:

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

The UML distinguishes an interface from other classes by placing the word "interface" in above the interface name.

Polymorphism allows for specifics to be dealt with during:

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

Declaring a method final means:

Which of the following does not complete the sentence correctly? An interface .

Which of the following statements about abstract superclasses is true?

Interfaces can have methods.

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?

A class that implements an interface but does not declare all of the interface's methods must be declared:

Introduction to Computers and Java

Introduction to Java Applications

Introduction to Classes and Objects

Control Statements: Part 1

Control Statements: Part 2

Methods: a Deeper Look

Arrays and Arraylists

Classes and Objects: a Deeper Look

Object Oriented Programming: Inheritance

Exception Handling

Atm Case Study,part 1: Object-Oriented Design With the Uml

Atm Case Study,part 2: Implementing an Object-Oriented Design

Gui Components: Part 1

Graphics and Java 2d

Strings

Files,streams and Object Serialization

Recursion

Searching, Sorting and Big O

Generic Collections

Generic Classes and Methods

Custom Generic Data Structures

Applets and Java Web Start

Multimedia: Applets and Applications

Gui, Part 2

Multithreading

Networking

Accessing Databases With Jdbc

Java Server Faces Web Applications

Ajax-Enabled Jsf Web Applications

Web Services

Filters