Deck 3: A First Look at Classes and Objects

Question 1

Methods that operate on an object's fields are called

A) instance methods.
B) instance variables.
C) private methods.
D) public methods.

Answer 1

A

Question 2

You should not define a class field that is dependent upon the values of other class fields

A) in order to keep it current.
B) because it is redundant.
C) in order to avoid having stale data.
D) because it should be defined in another class.

Answer 2

C

Question 3

For the following code, which statement is not true?
Public class Sphere
{ private double radius;
Public double x;
Private double y;
Private double z;
}

A) The z field is available to code that is written outside the Sphere class.
B) The radius field is not available to code written outside the Sphere class.
C) The radius, x, y, and z fields are members of the Sphere class.
D) The x field is available to code that is written outside the Sphere class.

Answer 3

A

Question 4

You use this key word to import a class.

A) import
B) assume
C) use
D) link

Question 5

The key word new

A) creates a new class.
B) creates a new Java byte code file.
C) creates an object in memory.
D) creates a new variable in memory.

Question 6

The scope of a local variable is

A) inside the parentheses of a method header.
B) the method in which they are defined.
C) inside the class, but not inside any method.
D) the entire class.

Question 7

Another term for an object of a class is a(n)

A) access specifier.
B) instance.
C) member.
D) method.

Question 8

A constructor is a method that

A) returns an object of the class.
B) never receives any arguments.
C) performs initialization or setup operations.
D) removes the object from memory.

Question 9

A group of related classes is called a(n)

A) archive.
B) package.
C) collection.
D) attachment.

Question 10

UML diagrams do not contain

A) fields.
B) methods.
C) class names.
D) object names.

Question 11

A class's responsibilities include

A) the things a class is responsible for knowing.
B) the things a class is responsible for doing.
C) both A and B
D) neither A nor B

Question 12

When an object is created, the attributes associated with the object are called

A) instance fields.
B) class instances.
C) instance methods.
D) fixed attributes.

Question 13

Class objects normally have ________ that perform useful operations on their data, but primitive variables do not.

A) fields
B) relationships
C) methods
D) instances

Question 14

Data hiding, which means that critical data stored inside the object is protected from code outside the object, is accomplished in Java by

A) using the public access specifier on the class methods.
B) using the private access specifier on the class methods.
C) using the private access specifier on the class fields.
D) using the private access specifier on the class definition.

Question 15

A method

A) may have zero or more parameter variables.
B) never has parameter variables.
C) must have at least two parameter variables.
D) may have only one parameter variables.

Question 16

Which of the following is not involved in finding the classes when developing an object-oriented application?

A) Describe the problem domain.
B) Write the code.
C) Refine the list of nouns to include only those that are relevant to the problem.
D) Identify all the nouns.

Question 17

What does the following UML diagram entry mean? + setHeight(h : double) : void

A) a public method with a parameter of data type double that does not return a value
B) a private field called Height that is a double data type
C) a private method with no parameters that returns a double data type
D) a public field called Height that is a double data type

Question 18

In the blueprint/house analogy, think of a class as a blueprint that describes a house and ________ as instances of the house built from the blueprint.

A) methods
B) fields
C) objects
D) attributes

Question 19

It is common practice in object-oriented programming to make all of a class's

A) fields private.
B) methods private.
C) fields public.
D) fields and methods public.

Question 20

In UML diagrams, what symbol indicates that a member is public?

A) -
B) *
C) #
D) +

Question 21

The public access specifier for a field indicates that the field may not be accessed by statements outside the class.

Question 22

The java.lang package is automatically imported into all Java programs.

Question 23

When an argument is passed by value,

A) the parameter variable holds the address of the argument.
B) the parameter variable cannot be changed.
C) the parameter variable holds a copy of the value passed to it.
D) changes can be made to the argument variable.

Question 24

A method that gets a value from a class's field but does not change it is known as a mutator method.

Question 25

The term "default constructor" is applied to the first constructor written by the author of the class.

Question 26

What is the following statement an example of? import java.util.*;

A) an explicit import statement
B) an unconditional import statement
C) a wildcard import statement
D) a conditional import statement

Question 27

The term "no-arg constructor" is applied to any constructor that does not accept arguments.

Question 28

A constructor is a method that is automatically called when an object is created.

Question 29

When a local variable in an instance method has the same name as an instance field, the instance field hides the local variable.

Question 30

A method that stores a value in a class's field or in some other way changed the value of a field is known as a mutator method.

Question 31

A constructor

A) always accepts two arguments.
B) has the same name as the class.
C) has return type of void.
D) always has an access specifier of private.

Question 32

An access specifier indicates how the class may be accessed.

Question 33

If you do not provide initialization values for a class's numeric fields, they will

A) cause a runtime error.
B) contain an unknown value.
C) be automatically initialized with 0.
D) cause a compiler error.

Question 34

A UML diagram uses the ________ symbol to indicate that a member is private.

A) *
B) -
C) #
D) +

Question 35

For the following code, which statement is not true?
Public class Circle
{ private double radius;
Public double x;
Private double y;
}

A) The y field is available to code that is written outside the Circle class.
B) The radius field is not available to code written outside the Circle class.
C) The radius, x, and y fields are members of the Circle class.
D) The x field is available to code that is written outside the Circle class.

Question 36

What is the following statement an example of? import java.util.Scanner;

A) an explicit import statement
B) an unconditional import statement
C) a wildcard import statement
D) a conditional import statement

Question 37

One or more objects may be created from a(n)

A) field.
B) method.
C) instance.
D) class.

Question 38

Shadowing is the term used to describe where the field name is hidden by the name of a local or parameter variable.

Question 39

To indicate the data type of a variable in a UML diagram, you specify

A) the variable name followed by the data type.
B) the class name followed by the variable name followed by the data type.
C) the variable name followed by a colon and the data type.
D) the data type followed by the variable name.

Question 40

After the header, the body of the method appears inside a set of

A) braces, {}.
B) parentheses, ().
C) brackets, [].
D) double quotes, "" .