Deck 7: Object-Oriented Programming, Part 2: User-Defined Classes

Question 1

Which access modifier can be referenced by methods of the same class only?

A) Public
B) Private
C) Protected
D) None of these is correct.

Answer 1

B

Question 2

What is the purpose of class constructors?

A) To initiate private access modifiers
B) To return a void
C) To initialize the instance variables of the new object
D) All of these are correct.

Answer 2

C

Question 3

Inside the curly braces we define the data of the class, called its ___________, and the methods.

A) fields
B) client programs
C) access modifier
D) loop updater

Answer 3

A

Question 4

Which of the following is a correct class name?

A) Execute
B) String
C) math
D) add

Question 5

The instance variables of a class hold the data for each object of that class.

Question 6

What will happen if you do not put curly braces around a method body?

A) You will get the message illegal start of expression.
B) You will get the message ';' expected.
C) You will get one or more compiler errors.
D) All of these are correct.

Question 7

If the return type of the method is void, as in main, there is no need for a return statement. Given that control automatically returns to the caller when the end of the method is reached, most programmers omit the return statement in void methods.

Question 8

Which of the following statements regarding the default initial value of instance variables byte and boolean is correct?

A) The instance variable byte is treated like the variable float, whereas boolean is given the same value as double.
B) Like byte, boolean is given the value of null.
C) Numeric variables such as boolean are given the value of 0 and byte variables are given the value false.
D) Numeric variables such as byte are given the value of 0 and boolean variables are given the value false.

Question 9

Which of the following is an advantage of providing multiple constructors?

A) It allows the method to skip the default constructor.
B) It gives the client the ability to avoid overloading the method.
C) It gives the client a choice of ways to create an object.
D) None of these is correct.

Question 10

If you do not write a constructor for a class, the compiler will provide a default constructor.

Question 11

The following is the general form of which method?
Public void setInstanceVariable( dataType newValue )
{
// validate newValue, then assign to the instance variable
}

A) Mutator
B) Uneven
C) Public
D) Autoclass

Question 12

Declaring a variable with the same name as the parameter of a method inside the method body will not have any effect.

Question 13

How does a method know for which object the method was called?

A) Any instance variable referred to by a method is considered to be declared to the object.
B) JVM sets the object reference, setName, to refer to the object for which the method has been called.
C) JVM sets the object reference, this, to refer to the object for which the method has been called.
D) None of these is correct.

Question 14

A parameter to a mutator method with the same name as the instance variable being changed hides the instance variable.

Question 15

Why should you provide new versions of the toString and equals methods from the Object class?

A) To get better functionality
B) To get a true return
C) To be able to change headers
D) All of these are correct.

Question 16

The __________ method is called automatically when an object reference is used as a String.

A) enum
B) toString
C) overriding
D) getName

Question 17

An instance method can reference which of the following?

A) Class variables
B) Instance variables
C) Class methods
D) All of these are correct.

Question 18

Methods that are defined to be non-static are subject to which of the following important restrictions?

A) Can reference only static variables
B) Cannot use the object reference this
C) Both reference only static variables and not use the object reference this
D) None of these is correct.

Question 19

When you define a static variable for your class, it is better to define its accessor and mutator methods as class methods.

Question 20

static variables that are constants are usually declared to be public because they typically are provided to allow the client to set preferences for the operations of a class. If you define a static variable for your class that is not a constant, it is best to define it as private and provide accessor and mutator methods, as appropriate, for client access to the static variable.

Question 21

Static data belong to the class, rather than to a particular object, or instance, of the class.

Question 22

Which of the following is a similarity between ordinal( ) and compareTo( Enum eObj )?

A) Both return enum
B) Both return 0 if two objects are the same
C) Both return int
D) Both set the default value as 0

Question 23

The enum objects are instantiated as constant objects, meaning that their values can be changed.

Question 24

enum Colors { RED, YELLOW, BLUE }; can be used to write a statement that represents colors in various order.

Question 25

The enum functionality is built into java.lang, so we must use an import statement to define enum types.

Question 26

A _____________ is a collection of related classes that can be imported into programs.

A) package
B) name program
C) valueOf method
D) main method

Question 27

Name duplication is when a file with the same name as a file you are trying to use already exists.

Question 28

Which of the following is not one of the criteria for a well-defined class?

A) The class should be easy to understand and use.
B) The class documentation should be clear, easy to understand, and complete.
C) The class documentation should represent the class well.
D) All of these are criteria for a well-defined class.

Question 29

How should slashes and asterisks be used in a Javadoc comment?

A) Start with /* and end it with /**.
B) Start with /* and end with */.
C) Start with /** and end with */.
D) None of these is correct.

Question 30

Javadoc is an executable program used to produce HTML-based documentation similar to the documentation available on Oracle's Java website.

Question 31

Javadoc recognizes two types of tags: block tags and comment tags.

Question 32

Block tags start with the character @.

Question 33

Javadoc discards all whitespace characters and the * at the beginning of each line until a non-whitespace character and non * character is encountered, so starting each comment with an * makes the Javadoc stand out.

Question 34

The data type of the return value of the toString method is:

A) Object.
B) boolean.
C) String.
D) class.

Question 35

The data type of the return value of the equals method is:

A) Object.
B) boolean.
C) equals.
D) class.

Question 36

The enum functionality is built into which package?

A) java.enum
B) java.lang
C) java.io
D) java.util
E) java.text

Question 37

A javadoc comment starts with:

A) //.
B) /*.
C) /**.
D) */.

Question 38

A javadoc comment ends with:

A) //.
B) /*.
C) /**.
D) */.

Question 39

Mutator methods can be void methods or can return the reference this.

Question 40

Mutator methods take no parameters.

Question 41

The access modifier of accessor and mutator methods is usually __________.

Question 42

A method parameter or local variable that has the same name as an instance variable will __________ that instance variable.

Question 43

The enum objects are instantiated as __________ objects.

Question 44

A package statement uses the keyword __________.

Question 45

The __________ method typically returns a String representation of the object data.

Question 46

A(n) _________ is a collection of classes that can be imported into a program.

Question 47

In the instance variable declaration private int value:

A) private is the access modifier, int is the name of the instance variable, and value is the data type.
B) private is the name of the instance variable, int is the data type, and value is the access modifier.
C) private is the access modifier, int is the data type, and value is the name of the instance variable.
D) private is the data type, int is the access modifier, and value is the name of the instance variable.

Question 48

A method of a class can access:

A) only the instance variables of its class.
B) only its parameters.
C) only the local variables the method defines.
D) the instance variables of its class, its parameters, and its local variables.

Question 49

It is possible to create user-defined classes in Java.

Question 50

The body of a method must be surrounded by curly braces.

Question 51

The default constructor takes no parameters.

Question 52

A method of a class can call other methods of that same class.

Question 53

Accessor methods are void methods.

Question 54

Accessor methods take no parameters.

Question 55

static methods can use the object reference this.

Question 56

static methods can call non-static methods.

Question 57

static methods can reference non-static variables.

Question 58

When we initialize an enum type, we use String literals.

Question 59

In the class header public class TV, public is the access modifier and TV is the name of the class.

Question 60

The access modifier of constructors should be __________.

Question 61

When we provide several constructors, we are __________ that method.

Question 62

The name of a method, along with its parameter list, is called the __________ of that method.

Question 63

The reference __________ refers to the object reference with which this method has been called.

Question 64

When we code the toString method of a class, we are __________ the toString method of the Object class.

Question 65

We can define class variables using the keyword __________.

Question 66

price is an instance variable of a class. Inside the method public void change( int price ), how do we refer to the instance variable price and not the parameter price?

Question 67

What are the three access modifiers?

Question 68

In addition to modifying the value of an instance variable, what is the other function of a mutator method?

Question 69

What syntax is used to define a class?

Question 70

Analyze why a programmer would want to make known the public method names and their APIs, but not the code of the class.

Question 71

Compare and contrast methods with instance variables.

Question 72

Construct a method in which you could omit the return expression.

Question 73

Suppose Angelica ran a program with multiple constructors and got a compiler error. How could she improve her program to avoid the error?

Question 74

What is an advantage of returning the reference this for several methods-for example, mutators?

Question 75

How would you defend taking the time to design your own classes?

Question 76

In terms of accessing instance variables, are static or non-static variables more restricted?

Question 77

What is Javadoc?

Question 78

Give an example of a Javadoc tag.