Question 1

If a method does not have a return statement, then

Accepted Answer

A)  it will produce a syntax error when compiled 
B)  it must be a void method 
C)  it can not be called from outside the class that defined the method 
D)  it must be defined to be a public method 
E)  it must be an int, double, float or String method 
A)  it will produce a syntax error when compiled 
B)  it must be a void method 
C)  it can not be called from outside the class that defined the method 
D)  it must be defined to be a public method 
E)  it must be an int, double, float or String method B

Question 2

Consider a Rational class designed to represent rational numbers as a pair of int's, along with methods reduce (to reduce the rational to simplest form), gcd (to find the greatest common divisor of two int's), as well as methods for addition, subtraction, multiplication, and division. Why should the reduce and gcd methods be declared to be private.

Accepted Answer

A)  Because they will never be used 
B)  Because they will only be called from methods inside of Rational 
C)  Because they will only be called from the constructor of Rational 
D)  Because they do not use any of Rational's instance data 
E)  Because it is a typo and they should be declared as public 
A)  Because they will never be used 
B)  Because they will only be called from methods inside of Rational 
C)  Because they will only be called from the constructor of Rational 
D)  Because they do not use any of Rational's instance data 
E)  Because it is a typo and they should be declared as public B

Question 3

Write a toString method that returns the player's name, position and batting average formatted to have 1 digit to the left of the decimal and 3 digits to the right of the decimal. Assume DecimalFormat has been imported.

Accepted Answer

public String toString( )
{
DecimalFormat df = new DecimalFormat("0.000");
return name + "	" + position + "	" + df.format(battingAverage);
}

Question 4

A constructor may contain a return statement so long as no value (or expression) is returned.

Accepted Answer

A) True 
 B)False

Question 5

Accessors and mutators provide mechanisms for controlled access to a well-encapsulated class.

Accepted Answer

A) True 
 B)False

Question 6

The relationship between a class and an object is best described as

Accepted Answer

A)  classes are instances of objects 
B)  objects are instances of classes 
C)  objects and classes are the same thing 
D)  classes are programs while objects are variables 
E)  objects are the instance data of classes 
A)  classes are instances of objects 
B)  objects are instances of classes 
C)  objects and classes are the same thing 
D)  classes are programs while objects are variables 
E)  objects are the instance data of classes

Question 7

For the questions below, use the following class definition.
import java.text.DecimalFormat;
public class Student
{
private String name;
private String major;
private double gpa;
private int hours;
public Student(String newName, String newMajor, double newGPA, int newHours)
{
name = newName;
major = newMajor;
gpa = newGPA;
hours = newHours;
}
public String toString( )
{
DecimalFormat df = new DecimalFormat("xxxx"); // xxxx needs to be replaced
return name + "
" + major + "
" + df.format(gpa) + "
" + hours
}
}
-Assume that another method has been defined that will compute and return the student's class rank (Freshman, Sophomore, etc). It is defined as: public String getClassRank( )
Given that s1 is a student, which of the following would properly be used to get s1's class rank?

Accepted Answer

A)  s1 = getClassRank( ); 
B)  s1.toString( ); 
C)  s1.getHours( ); 
D)  s1.getClassRank( ); 
E)  getClassRank(s1); 
A)  s1 = getClassRank( ); 
B)  s1.toString( ); 
C)  s1.getHours( ); 
D)  s1.getClassRank( ); 
E)  getClassRank(s1);

Question 8

Formal parameters are those that appear in the method call and actual parameters are those that appear in the method header.

Accepted Answer

A) True 
 B)False

Question 9

The behavior of an object is defined by the object's

Accepted Answer

A)  instance data 
B)  constructor 
C)  visibility modifiers 
D)  methods 
E)  all of the above 
A)  instance data 
B)  constructor 
C)  visibility modifiers 
D)  methods 
E)  all of the above

Question 10

Consider a sequence of method invocations as follows: main calls m1, m1 calls m2, m2 calls m3 and then m2 calls m4, m3 calls m5. If m4 has just terminated, what method will resume execution?

Accepted Answer

A)  m1 
B)  m2 
C)  m3 
D)  m5 
E)  main 
A)  m1 
B)  m2 
C)  m3 
D)  m5 
E)  main

Question 11

An example of passing message to a String where the message has a String parameter would occur in which of the following messages?

Accepted Answer

A)  length 
B)  substring 
C)  equals 
D)  toUpperCase 
E)  none of the above, it is not possible to pass a String as a parameter in a message to a String 
A)  length 
B)  substring 
C)  equals 
D)  toUpperCase 
E)  none of the above, it is not possible to pass a String as a parameter in a message to a String

Question 12

In order to preserve encapsulation of an object, we would do all of the following except for which one?

Accepted Answer

A)  Make the instance data private 
B)  Define the methods in the class to access and manipulate the instance data 
C)  Make the methods of the class public 
D)  Make the class final 
E)  All of the above preserve encapsulation 
A)  Make the instance data private 
B)  Define the methods in the class to access and manipulate the instance data 
C)  Make the methods of the class public 
D)  Make the class final 
E)  All of the above preserve encapsulation

Question 13

For the questions below, use the following class definition.
import java.text.DecimalFormat;
public class Student
{
private String name;
private String major;
private double gpa;
private int hours;
public Student(String newName, String newMajor, double newGPA, int newHours)
{
name = newName;
major = newMajor;
gpa = newGPA;
hours = newHours;
}
public String toString( )
{
DecimalFormat df = new DecimalFormat("xxxx"); // xxxx needs to be replaced
return name + "
" + major + "
" + df.format(gpa) + "
" + hours
}
}
-Which of the following patterns should be used in place of "xxxx" when instantiating df so that the gpa to be output in typical form (like 3.810)?

Accepted Answer

A)  "#.###" 
B)  "#.0" 
C)  "0.# " 
D)  "0.000" 
E)  "0.0##" 
A)  "#.###" 
B)  "#.0" 
C)  "0.# " 
D)  "0.000" 
E)  "0.0##"

Question 14

When reasoning about a car, we use such information as its make and model, year, color, cost (or worth), number of miles, gas mileage, insurance cost, and so forth. Consider a program that will attempt to determine how practical a car might be on a road trip. Which of these types of information might you use in your program as instance data?
 Provide a justification for your selection.

Accepted Answer

Because a road trip will include such fa

Question 15

While multiple objects of the same class can exist, in a given program there can be only one version of each class.

Accepted Answer

A) True 
 B)False

Question 16

Explain why it would be a poor decision to make instance data public instead of private. Give an example of why this could result in a problem.

Accepted Answer

If the instance data are public, then an

Question 17

A GUI container is an object that defines a screen element.

Accepted Answer

A) True 
 B)False

Question 18

Java methods can return more than one item if they are modified with the reserved word continue, as in public continue int foo( ) { ... }

Accepted Answer

A) True 
 B)False

Question 19

A variable whose scope is restricted to the method where it was declared is known as a(n)

Accepted Answer

A)  parameter 
B)  global variable 
C)  local variable 
D)  public instance data 
E)  private instance data 
A)  parameter 
B)  global variable 
C)  local variable 
D)  public instance data 
E)  private instance data

Question 20

Defining formal parameters requires including each parameters type.

Accepted Answer

A) True 
 B)False

If a method does not have a return statement, then

Write a toString method that returns the player's name, position and batting average formatted to have 1 digit to the left of the decimal and 3 digits to the right of the decimal. Assume DecimalFormat has been imported.

A constructor may contain a return statement so long as no value (or expression) is returned.

Accessors and mutators provide mechanisms for controlled access to a well-encapsulated class.

The relationship between a class and an object is best described as

Formal parameters are those that appear in the method call and actual parameters are those that appear in the method header.

The behavior of an object is defined by the object's

Consider a sequence of method invocations as follows: main calls m1, m1 calls m2, m2 calls m3 and then m2 calls m4, m3 calls m5. If m4 has just terminated, what method will resume execution?

An example of passing message to a String where the message has a String parameter would occur in which of the following messages?

In order to preserve encapsulation of an object, we would do all of the following except for which one?

While multiple objects of the same class can exist, in a given program there can be only one version of each class.

Explain why it would be a poor decision to make instance data public instead of private. Give an example of why this could result in a problem.

A GUI container is an object that defines a screen element.

Java methods can return more than one item if they are modified with the reserved word continue, as in public continue int foo( ) { ... }

A variable whose scope is restricted to the method where it was declared is known as a(n)

Defining formal parameters requires including each parameters type.

Introduction

Data and Expressions

Using Classes and Objects

Conditionals and Loops

More Conditionals and Loops

Object-Oriented Design

Arrays

Inheritance

Polymorphism

Exceptions

Recursion

Collections

Filters

Exam 4: Writing Classes

If a method does not have a return statement, then

Write a toString method that returns the player's name, position and batting average formatted to have 1 digit to the left of the decimal and 3 digits to the right of the decimal. Assume DecimalFormat has been imported.

A constructor may contain a return statement so long as no value (or expression) is returned.

Accessors and mutators provide mechanisms for controlled access to a well-encapsulated class.

The relationship between a class and an object is best described as

Formal parameters are those that appear in the method call and actual parameters are those that appear in the method header.

The behavior of an object is defined by the object's

Consider a sequence of method invocations as follows: main calls m1, m1 calls m2, m2 calls m3 and then m2 calls m4, m3 calls m5. If m4 has just terminated, what method will resume execution?

An example of passing message to a String where the message has a String parameter would occur in which of the following messages?

In order to preserve encapsulation of an object, we would do all of the following except for which one?

While multiple objects of the same class can exist, in a given program there can be only one version of each class.

Explain why it would be a poor decision to make instance data public instead of private. Give an example of why this could result in a problem.

A GUI container is an object that defines a screen element.

Java methods can return more than one item if they are modified with the reserved word continue, as in public continue int foo( ) { ... }

A variable whose scope is restricted to the method where it was declared is known as a(n)

Defining formal parameters requires including each parameters type.

Introduction

Data and Expressions

Using Classes and Objects

Conditionals and Loops

More Conditionals and Loops

Object-Oriented Design

Arrays

Inheritance

Polymorphism

Exceptions

Recursion

Collections

Filters