cs

Question 1

Output?

public static void main(String [] args){
int number = 6;
int secondNumber = changeNumber (number);
System.out.print(number + “ “ + secondNumber);
}

      public static int changeNumber(int number){
        number = 12;
        return number;
      }

Answer 1

6 12

Question 2

Which Line will Line A produce?

public class Unknown{
private int x;

            public Unknown(){
                x = 17;
                method1();
                method2(5);
                method3();
                System.out.println(x);      // Line D
            }
        
            public void method1(){
                --x;
                int x = this.x;
                x++;
                System.out.println(this.x); // Line A
            }
        
            public void method2(int x){
                x++;
                System.out.println(x);      // Line B
            }
        
            public void method3(){
                --x;
                int x = 2;
                x++;
                System.out.println(x);      // Line C
            }
        }

Answer 2

16

Question 3

Output?

public void foo () {
int x = 42;
int y = 24;
mystery (x, y);
System.out.println (x + “ “ + y);
}

        public void mystery (int var1, int var2) {
          int temp = var1;
          var1 = var2;
          var2 = temp;
        }

Answer 3

42 24

Question 4

What should be done to correct the following code?

public class exam {
float mark;
public static void main(String[]arg){
float aCopyofMark;
exam e = new exam();
System.out.println( e.mark + aCopyofMark);
}
}

Answer 4

Initalize aCopyofMark

Question 5

How many objects are created in the following declaration?

String name;

Answer 5

0

Question 6

Output?

int income = 30;
boolean condition1 = true, condition2 = true;
if(income < 100)
if(income > 10)
if(condition1){
System.out.print(“A”);
if(income < 20)
System.out.print(“B”);
}
else
System.out.print(“C”);
if(!condition2){
if(income > 50)
System.out.print(“D”);
}
else{
System.out.print(“E”);
}

Answer 6

AE

Question 7

The scope of a variable in Java is:

Answer 7

The part of the program in which it can be used

Question 8

Which of the following JUnit tests will fail?

Answer 8

assertNull(50-25-25);

Question 9

Imagine a class named Club, to be a member a person must be aged 15 or older, but less than 50. What values would you use to boundary test a method designed to check if a person was a suitable age to join?

Answer 9

14 15 49 50

Question 10

Which set of values is just enough to provide code coverage for the following code: if (cost > 10 && tip > 4)

cost: 20 and tip: 2, cost: 20 and tip: 6, cost: 9 and tip: 1, cost: 9 and tip: 6

cost: 20 and tip: 4, cost: 5 and tip: 1

cost: 20 and tip: 2, cost: 9 and tip: 5, cost: 15 and tip: 6

Answer 10

cost: 20 and tip: 2, cost: 9 and tip: 5, cost: 15 and tip: 6

Question 11

Which set of values is just enough to provide code coverage for the following code: if (cost < 10 || cost >20)

cost: 5, 10, 15, 20

cost: 5, 25

cost: 5, 25, 15

Answer 11

cost: 5, 25, 15

Question 12

Which line of code is needed at the beginning of the follow block of code used to test whether remove throws the correct exception:

          try
          {
            collection.remove(item);
          }
          catch (Exception exception)
          {
            thrown = exception;
          }

          assertNotNull(thrown);

          assertTrue(thrown instanceof NoSuchElementException);

          assertEquals(thrown.getMessage(), "That item is not in the collection.");

Exception thrown;

Exception thrown = null;

Exception thrown = NoSuchElementException;

Exception thrown = That item is not in the collection.”;

Answer 12

Exception thrown = null;

Question 13

Which of the following lines of code would properly test the equality of two arrays. For example:

        Object[] expectedArray = {"H","I","J","K"};
        Object[] actualArray = {"A","B","C","D"};            

assertEquals(expectedArray, actualArray);

assertEquals(actualArray, expectedArray);

      if (actualArray.length == expectedArray.length) {
        for (int i =0; i < expectedArray.length; i++)
        {
          assertEquals(expectedArray[i],actualArray[i]);
        }  
      }

      for (int i =0; i < expectedArray.length; i++)
      {
        assertEquals(expectedArray[i],actualArray[i]);
      }  

      for (int i =0; i < actualArray.length; i++)
       {
        assertEquals(expectedArray[i],actualArray[i]);
      }  

assertTrue( expectedArray.equals( actualArray) );

Answer 13

if (actualArray.length == expectedArray.length) {
for (int i =0; i < expectedArray.length; i++)
{
assertEquals(expectedArray[i],actualArray[i]);
}
}

Question 14

Suppose you are writing a method in a new class. You are also writing unit test cases to demonstrate that this method works correctly. You know you have written enough test cases to demonstrate the method works as desired when?

You have written at least one test case for every input value that can be given to the method.

You have written at least one test case for every output value that can be produced by the method.

You have written at least one test case that uses the method.

You have written at least one test case for every input/output value combination that can be given to/produced by the method.

You have written separate test cases for each identifiable “group” of input values and/or output values where the behavior is expected to be similar.

Answer 14

You have written separate test cases for each identifiable “group” of input values and/or output values where the behavior is expected to be similar.

Question 15

Which method is run before each test method?

All of these answers are correct

public void setUp(){}

public void SetUp(){}

public Hokie(){}

public void setup(){}

public void SetUp(){}, public void setup(){}, and public Hokie(){} are all correct

Answer 15

public void setUp(){}

Question 16

Which of the following is false according to the course style guidelines?

constants use a reverse camel case convention

package names should be all lowercase

methods and variable follow the same naming convention

classes and interfaces both follow the same naming convention

Answer 16

constants use a reverse camel case convention

Question 17

Reasons for following style and documentation guidelines are:

code is easier to debug

code is more readable and easier to understand

all of these

code is easier to maintain

Answer 17

all of these

Question 18

Which of the following is not a commonly used javadoc tag?

@return

@version

@param

@args

@author

Answer 18

@args

Question 19

Which of the following do not need to be avoided to adhere to the course style guidelines

unused fields/variables

sufficient javadocs

lines that are too long

debug statements left within the code

hardcoded values

Answer 19

sufficient javadocs

Question 20

When an exception occurs within a method, the method creates an Exception object then hands it off to the Java runtime system to take further action, this is referred to as…

instantiating a semaphore

exception passing

runtime passing

throwing an exception

Answer 20

throwing an exception

Question 21

Which of the following could NOT result in code throwing a null pointer exception?

Using an object that became null

Attempting to use an object that was declared but never instantiated

Attempting to invoke a method from a null object

Attempting to use an object that was instantiated but never declared

Answer 21

Attempting to use an object that was instantiated but never declared

Question 22

True or False:
The following is a valid combination of try and finally blocks:

try {
// statements
}
finally {
// statements
}

Answer 22

True

Question 23

Which of the following statements are false?

A try block can have multiple catch blocks

A catch block must have an associated try block

Code in a finally block will always execute whether or not an exception occurs in the try block

A try block can have only one catch block

Answer 23

A try block can have only one catch block

Question 24

Which pair of code blocks are used to enclose exception-prone code, and to check for and handle exceptional events?

try and catch

catch and while

try and finally

if and then

Answer 24

try and catch

Question 25

We implement the following code and receive an error message on the riskyCodeThatWantsToDefer() method call indicating “Unhandled exception type IOException”.

public void riskyCodeThatWantsToDefer ( ) throws IOException {
// some code
}

public void callingMethod() {
riskyCodeThatWantsToDefer();
}
We realize that the riskyCodeThatWantsToDefer() method has passed exception handling responsibility to callingMethod().
To resolve this error we must modify callingMethod().
Which of the modifications listed below would resolve this error?

public static void callingMethod() {
try {
riskyCodeThatWantsToDefer();
}
catch (IOException e) {
e.printStackTrace();
}
}

public static void callingMethod() throws IOException {

riskyCodeThatWantsToDefer();
}

Both of these answers are correct

Answer 25

Both of these answers are correct

Question 26

Consider the following: When foo is executed, what is printed out?

        public void foo () {
          int x = 42;
          int y = 24;
          mystery (x, y);
          System.out.println (x + "  " + y);
        }

        public void mystery (int var1, int var2) {
          int temp = var1;
          var1 = var2;
          var2 = temp;
        }

42 24

24 42

Answer 26

42 24

Question 27

What kind of variable is label?

        public class Labeller extends JFrame {
          public Labeller () {
            JLabel label = new JLabel("Field or Variable");
          }
         
          public static void main (String[] args) {
           new Labeller();
          }
        }

Instance variable, Object Reference

Instance variable, primitive

local variable, primitive

local variable, Object Reference

Answer 27

local variable, Object Reference

Question 28

Using the information in the UML diagram above, suppose an Oak prepares for winter like a Tree, but it drops its leaves first. What code should replace ??? in the following code?

public class Oak extends Tree {
…
public void prepareForWinter(){
this.dropLeaves();
???
}
}

this.absorb(new Water());

super(this);

super.this();

Tree.prepareForWinter();

super.prepareForWinter();

Answer 28

super.prepareForWinter();

Question 29

The simplified UML diagram above shows the relationships among Java classes Bird, Crow, and Duck. Suppose Bird has a fly(Location place) method, but we want Crows to makeNoise() just before they take off and then behave like other Birds. Assuming Crows have a makeNoise() method, we should

Define a fly method in Crow by copying the fly code from Bird then adding in makeNoise() at the start, i.e.

      public void fly(Location place) {
        this.makeNoise();
        //[paste the body of Bird's fly method here]
      }

Define a fly method in Crow that just consists of makeNoise() and this.fly(place), i.e.

      public void fly(Location place) {
        this.makeNoise();
        this.fly(place);
      }

Define a fly method in Crow that just consists of makeNoise() and super.fly(place)
public void fly(Location place) {
this.makeNoise();
super.fly(place);
}

Define a fly method in Crow that just consists of makeNoise() and Bird.fly(place); i.e.

      public void fly(Location place) {
        this.makeNoise();
        Bird.fly(place);
      }

Define a fly method in Crow that just consists of makeNoise(), i.e.

      public void fly(Location place) {
        this.makeNoise();
      }

Answer 29

Define a fly method in Crow that just consists of makeNoise() and super.fly(place)
public void fly(Location place) {
this.makeNoise();
super.fly(place);
}

Question 30

Given an array of doubles named values, what does the following code do?

        double total = 0;
        for(double element :  values)
        {
            total = total + element;
        }
        double average = 0;
        if (values.length > 0)
        {
            average = total/values.length;
        }

Answer 30

Calculates the sum and average of the values

Question 31

Given an array of ints named values, what does the following code do?

        for (int i = 0; i < values.length; i++)
        {
            values[i] = i * i;
        }

Calculates the sum and average of the values

Prints all the values

Finds the maximum of the values

Fills the array with squares (0, 1, 4, 9, 16, …)

Answer 31

Fills the array with squares (0, 1, 4, 9, 16, …)

Question 32

Given the following code:

          for (int i=0; i < values.length; i++) {
            if (values[i] == searchedValue){
              found = true; 
            } else {
              found = false;
            }
          } 
          if (found) { 
            System.out.println("found " + searchedValue); 
          } else { 
            System.out.println ("not found"); 
          }      

If the initital values are:

        int[] values = { 3, 6, 10, 12, 100, 200, 250, 500 };
        int searchedValue = 10;
        boolean found = false;

What is output?

found 10

not found

Answer 32

not found

Question 33

Given the following code:

        for (int i=0; i < values.length; i++) {
          if (values[i] == searchedValue){
            found = true; 
          } else {
            found = false;
          }
        } 
        if (found) { 
          System.out.println("found " + searchedValue); 
        } else { 
          System.out.println ("not found"); 
        }      

If the initial values are:

      int[] values = { 3, 6, 10, 12, 100, 200, 250, 500 };
      int searchedValue = 250;
      boolean found = false;

What is output?

found 250

not found

Answer 33

not found

Question 34

If currentSize is 8, trace

        int[] values = { 35, 16, 100, 12, 100, 200, 250, 500, 0, 0};
        int newElement = 11;
        if (currentSize < values.length) {
            currentSize++;
            values[currentSize - 1] = newElement;
        }

What is the array after the code executes?

{ 35, 16, 100, 12, 100, 200, 250, 500, 11, 0};

{ 35, 16, 100, 12, 100å, 200, 250, 11, 500, 0};

{ 35, 16, 100, 12, 100, 200, 250, 500, 0, 11};

{ 11, 35, 16, 100, 12, 100, 200, 250, 500, 0 };

{ 35, 11, 16, 100, 12, 100, 200, 250, 500, 0 };

{ 35, 11, 100, 12, 100, 200, 250, 500, 0, 0 };

Answer 34

{ 35, 16, 100, 12, 100, 200, 250, 500, 11, 0};

Question 35

If pos is 4 and currentSize is 7, trace this code that removes an item:

        int[] values = {10, 20, 30, 40, 50, 60, 70};
        for (int i = pos + 1; i < currentSize; i++) {
             values[i - 1] = values[i];
        }    

What is the array after the code executes?

{10, 20, 30, 40, 50, 60, 70}

{10, 20, 30, 40, 60, 70, 70}

{10, 20, 30, 50, 60, 70, 70}

{10, 20, 30, 40, 70, 60, 50}

Answer 35

{10, 20, 30, 40, 60, 70, 70}

Question 36

Given the following code:

        public class MoveData {

            public static  void shiftUpArray(T[] dataset)
            {
                for (int i =1; i < dataset.length; i++) {
                    dataset[i] = dataset[i-1];
                }
            }
        
          public static void main(String args[]) {
          
          }
        
        
        ...
        }

Which of the following would not be possible correct code inside the main method of MoveData?

        Integer[] bits = {32, 64, 256, 512};
        shiftUpArray(bits);
      

        WritingInstrument[] box = new WritingInstrument[20];
        box[0] = new Marker();
        box[1] = new Marker();
        box[2] = new Pencil();
        shiftUpArray(box);
      

        int[] scores = {92, 18, 76, 76};
        shiftUpArray(scores);
      

        String[] oceans = {"Pacific", "Indian", "Atlantic", "Arctic"}; 
        shiftUpArray(oceans);

Answer 36

int[] scores = {92, 18, 76, 76};
shiftUpArray(scores);

Question 37

The use of a generic data type is preferred over using Object as a general class in a collection because…

It ensures that all the members of the collection are objects related by inheritance.

It allows the data type to be determined later by the client of the class.

It can contain objects of type OrderedPair.

Answer 37

It ensures that all the members of the collection are objects related by inheritance.

Question 38

What does the add method return?

True if the addition is successful, or false if not.

True if the bag contains anEntry, or false if not.

The values array filled with the entries in the bag.

The object that was added.

Answer 38

True if the addition is successful, or false if not.

Question 39

A set is an abstract data type that is similar to a bag. It is also unordered, but it does not allow duplicates. Examples of sets would be even integers or a collection of the movies you have previously seen. Which bag behavior would need to be modified for a set?

contains

clear

toArray

add

Answer 39

add

Question 40

Junit testing…

Provides ability to test specific methods

All of these answers are correct

Has a setUp method useful for initializing variables

Should be used throughout development

Uses assert statements instead of print statements

Answer 40

All of these answers are correct

Question 41

In the Fixed Size Array implementation of a Bag, depicted below as ArrayBag1, what happens when a client tries to add an element to the ArrayBag1 but the underlying array is full?

UML Diagram of Bags

The add method throws an exception

The element does not get added

The add method doubles its size and adds the new element

The add method replaces the last element with the new element

Answer 41

The element does not get added

Question 42

Which of the following 5 implementations could not be used for contains?

public boolean contains(T anEntry)
{
return getFrequencyOf(anEntry) > 0;
}

public boolean contains(T anEntry)
{
boolean found = false;
int i = 0;
while ( !found && (i < numberOfEntries))
{
if (anEntry.equals(contents[i]))
{
found = true;
}
i++;
}
return found;
}

public boolean contains(T anEntry)
{
return !isEmpty();
}

public boolean contains(T anEntry)
{
return getIndexOf(anEntry) > -1;
}

public boolean contains(T anEntry)
{
int i = 0;
while (i < numberOfEntries)
{
if (anEntry.equals(contents[i]))
{
return true;
}
i++;
}
return false;
}

Answer 42

public boolean contains(T anEntry)
{
return !isEmpty();
}

Question 43

Which of the following 5 implementations could not be used for getFrequency?

public int getFrequencyOf(T anEntry)
{
int i = 0;
int count = 0;
while(anEntry.equals(contents[i]))
{
i++;
count++;
}
return numberOfEntries - count;
}

public int getFrequencyOf(T anEntry)
{
int count = 0;
for(int i = numberOfEntries - 1; i > -1; i–)
{
if(anEntry.equals(contents[i]))
{
count++;
}
}
return count;
}

public int getFrequencyOf(T anEntry)
{
int i = 0;
int count = 0;
while( i < numberOfEntries)
{
if(anEntry.equals(contents[i]))
{
count++;
}
i++;
}
return count;
}

public int getFrequencyOf(T anEntry)
{
int count = 0;
for(int i = 0; i < numberOfEntries; i++)
{
if(anEntry.equals(contents[i]))
{
count++;
}
}
return count;
}

public int getFrequencyOf(T anEntry)
{
int count = 0;
for(int i = numberOfEntries - 1; i >= 0; i–)
{
if(anEntry.equals(contents[i]))
{
count++;
}
}
return count;
}

Answer 43

public int getFrequencyOf(T anEntry)
{
int i = 0;
int count = 0;
while(anEntry.equals(contents[i]))
{
i++;
count++;
}
return numberOfEntries - count;
}

Question 44

package linkedchain;

public class LinkedChain {

private Node head; // Reference to first node
private int numberOfEntries;

public static void main(String[] args) {

  LinkedChain chain = new LinkedChain();
  chain.add(10);
  chain.add(-2);
  chain.add(57);    }

public LinkedChain() {
head = null;
numberOfEntries = 0;
} // end default constructor

public void add(int newEntry) {
// Add to beginning of chain:
Node newNode = new Node(newEntry);
newNode.next = head; // Make new node reference rest of chain
head = newNode; // New node is at beginning of chain
numberOfEntries++;
} // end add

private class Node {
private int data;
private Node next; // Link to next node

  private Node(int dataPortion) {
     this(dataPortion, null);
  } // end constructor

  private Node(int dataPortion, Node nextNode) {
     data = dataPortion;
     next = nextNode;
  } // end constructor    } // end Node }

For this question, refer back to the code in LinkedChain class in the course material What if the line statement

chain.add(40);
was added before the line

chain.add(10);
what would the the order of the integers be starting at the front of the chain?

57, -2, 10, 40

10, -2, 57, 40

40, 10, -2, 57

40, 57, -2, 10

Answer 44

57, -2, 10, 40

Question 45

package linkedchain;

public class LinkedChain {

private Node head; // Reference to first node
private int numberOfEntries;

public static void main(String[] args) {

  LinkedChain chain = new LinkedChain();
  chain.add(10);
  chain.add(-2);
  chain.add(57);    }

public LinkedChain() {
head = null;
numberOfEntries = 0;
} // end default constructor

public void add(int newEntry) {
// Add to beginning of chain:
Node newNode = new Node(newEntry);
newNode.next = head; // Make new node reference rest of chain
head = newNode; // New node is at beginning of chain
numberOfEntries++;
} // end add

private class Node {
private int data;
private Node next; // Link to next node

  private Node(int dataPortion) {
     this(dataPortion, null);
  } // end constructor

  private Node(int dataPortion, Node nextNode) {
     data = dataPortion;
     next = nextNode;
  } // end constructor    } // end Node }

For this question, refer back to the code in the LinkedChain class in the course material What if the line statement

chain.add(16);
was added after the line

chain.add(57);
what would the order of the integers be starting at the front of the chain?

16, 10, -2, 57

10, -2, 57, 16

16, 57, -2, 10

57, -2, 10, 16

Answer 45

16, 57, -2, 10

Question 46

This is a still image of the concept map for the term “pointers”. You can check the actual concept map on the glossary page.

Which among the following is true?

A pointer is a variable whose value is a default data type

A pointer is not a variable

A pointer is a variable whose value is the address of another variable

None of the above

Answer 46

A pointer is a variable whose value is the address of another variable

Question 47

Where does new data get added to this linked implementation of a bag?

Beginning

End

Middle

Answer 47

Beginning

Question 48

What are the two fields of a Node?

data and node

data and next

data and null

Answer 48

data and next

Question 49

Which of the following is a correct implementation of getFrequencyOf

public int getFrequencyOf(T anEntry)
{
int frequency = 0;

while ((currentNode != null)) {
Node currentNode = firstNode;
if (anEntry.equals(currentNode.getData())) {
frequency++;
} // end if

currentNode = currentNode.getNext();   } // end while

return frequency;
} // end getFrequencyOf

public int getFrequencyOf(T anEntry)
{
int frequency = 0;
Node currentNode = firstNode;
while ((currentNode != null)) {
if (anEntry.equals(currentNode.getData())) {
frequency++;
} // end if

currentNode = currentNode.getNext();   } // end while

return frequency;
} // end getFrequencyOf

public int getFrequencyOf(T anEntry)
{

Node currentNode = firstNode;
while ((currentNode != null)) {
if (anEntry.equals(currentNode.getData())) {
frequency++;
} // end if

currentNode = currentNode.getNext();   } // end while

return frequency;
} // end getFrequencyOf

public int getFrequencyOf(T anEntry)
{
int frequency = 0;
Node currentNode = firstNode;
while ((currentNode != null)) {
if (anEntry.equals(currentNode.getData())) {
frequency++;
} // end if

currentNode++;   } // end while

return frequency;
} // end getFrequencyOf

Answer 49

public int getFrequencyOf(T anEntry)
{
int frequency = 0;
Node currentNode = firstNode;
while ((currentNode != null)) {
if (anEntry.equals(currentNode.getData())) {
frequency++;
} // end if

currentNode = currentNode.getNext();   } // end while

return frequency;
} // end getFrequencyOf

Question 50

Which of the following implementations could not be used for contains?

public boolean contains(T anEntry)
{
return getIndexOf(anEntry) > -1;
}

public boolean contains(T anEntry) {

Node currentNode = firstNode;

while (!anEntry.equals(currentNode.getData())) {
currentNode = currentNode.getNext();
} // end while

return true;
} // end contains

public boolean contains(T anEntry)
{
return getFrequencyOf(anEntry) > 0;
}

public boolean contains(T anEntry)
{
boolean found = false;
Node currentNode = firstNode;

while (!found && (currentNode != null)) {
if (anEntry.equals(currentNode.getData()))
found = true;
else
currentNode = currentNode.getNext();
} // end while

return found;
} // end contains

Answer 50

public boolean contains(T anEntry) {

Node currentNode = firstNode;

while (!anEntry.equals(currentNode.getData())) {
currentNode = currentNode.getNext();
} // end while

return true;
} // end contains

Question 51

The method remove that has no parameter in the linked implementation

removes the first element in the chain

removes the last element in the chain

none of these answers are correct

Answer 51

removes the first element in the chain