2022
AP
®
Computer Science A
Sample Student Responses
and Scoring Commentary
Inside:
Free-Response Question 3
Scoring Guidelines
Student Samples
Scoring Commentary
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AP®ComputerScienceA2022ScoringGuidelines
©2022CollegeBoard
ApplyingtheScoringCriteria
Applythequestionscoringcriteriafirst,whichalwaystakesprecedence.Penaltypointscanonlybe
deductedinapartofthequestionthathasearnedcreditviathequestionrubric.Nopartofaquestion(a,b,c)
mayhaveanegativepointtotal.Agivenpenaltycanbeassessedonlyonceforaquestion,evenifitoccurs
multipletimesorinmultiplepartsofthatquestion.Amaximumof3penaltypointsmaybeassessedper
question.
1‐PointPenalty
v)
Array/collectionaccessconfusion( get)[]
w) Extraneouscodethatcausesside‐effect(e.g.,printingtooutput,incorrectpreconditioncheck)
x) Localvariablesusedbutnonedeclared
y) Destructionofpersistentdata(e.g.,changingvaluereferencedbyparameter)
z) Voidmethodorconstructorthatreturnsavalue
NoPenalty
Extraneouscodewithnoside‐effect(e.g.,validpreconditioncheck,no‐op)
Spelling/casediscrepancieswherethereisnoambiguity*
Localvariablenotdeclaredprovidedothervariablesaredeclaredinsomepart
private or public qualifieronalocalvariable
Missing public qualifieronclassorconstructorheader
Keywordusedasanidentifier
Commonmathematicalsymbolsusedforoperators(ו÷≤≥<>≠)
[] vs. () vs. <>
= insteadof == andviceversa
length/size confusionforarray, String, List, or ArrayList; withorwithout ( )
Extraneous [] whenreferencingentirearray
[i,j] insteadof [i][j]
Extraneoussizeinarraydeclaration,e.g., int[size] nums = new int[size];
Missing ; wherestructureclearlyconveysintent
Missing { } whereindentationclearlyconveysintent
Missing ( ) onparameter‐lessmethodorconstructorinvocations
Missing ( ) around if or while conditions
*Spellingandcasediscr
epanciesforidentifiersfallunderthe“NoPenalty”categoryonlyifthecorrectioncan
beunambiguouslyinferredfromcontext,forexample,“ArayList”insteadof“ArrayList”.Asacounterexample,
notethatifthecodedeclares "int G=99, g=0;", thenuses "while (G < 10)" insteadof
"while (g < 10)", thecontextdoesnotallowforthereadertoassumetheuseofthelowercase
variable.
AP®ComputerScienceA2022ScoringGuidelines
©2022CollegeBoard
Question3:Array/ArrayList 9points
Canonicalsolution
(a)
public double getAverageRating()
{
int sum = 0;
for (Review r : allReviews)
{
sum += r.getRating();
}
return (double) sum / allReviews.length;
}
3points
(b)
public ArrayList<String> collectComments()
{
ArrayList<String> commentList = new ArrayList<String>();
for (int i = 0; i < allReviews.length; i++)
{
String comment = allReviews[i].getComment();
if (comment.indexOf("!") >= 0)
{
String last =
comment.substring(comment.length() – 1);
if (!last.equals("!") && !last.equals("."))
{
comment += ".";
}
commentList.add(i + "-" + comment);
}
}
return commentList;
}
6points
AP®ComputerScienceA2022ScoringGuidelines
©2022CollegeBoard
(a)
getAverageRating
ScoringCriteria DecisionRules
1 Initializesandaccumulatessum
Responsecanstillearnthepointevenif
they
failtousealooptoaccumulate
failtocall getRating orcall
getRating incorrectly
1point
2
Accesseseveryelementof allReviews
(noboundserrors)
Responseswillnotearnthepointifthey
accesstheelementsof allReviews
incorrectly
1point
3 Computesandreturns double average
ratingbasedon getRating return
values(algorithm)
Responsecanstillearnthepointevenif
they
failtoinitializetheaccumulatorforthe
sum
Responseswillnotearnthepointifthey
failtoaccumulatethesumofallratings
useintegerdivisiontocomputeaverage
includeparametersoncallto
getRating
failtocall getRating onall
elementsof allReviews
1point
Totalforpart(a) 3points
AP®ComputerScienceA2022ScoringGuidelines
©2022CollegeBoard
(b)
collectComments
ScoringCriteria DecisionRules
4 Instantiatesan ArrayList capableof
holding String objects
1point
5 Accesseseveryelementof allReviews
(noboundserrors)
Responsescanstillearnthepointevenif
they
failtokeeptrackoftheindex
Responseswillnotearnthepointifthey
accesstheelementsof allReviews
incorrectly
1point
6
Calls getComment onanelementof
allReviews,callsatleastone String
methodappropriatelyonthe
getComment returnvalue,andall
String methodcallsaresyntactically
valid
Responsescanstillearnthepointevenif
they
callsomeofthe String methodson
objectsotherthan getComment
returnvalues
Responseswillnotearnthepointifthey
includeaparameterwhencalling
getComment
callany String methodsincorrectly
callany String methodsonobjects
otherthan String values
1point
7
Comparesthefinalcharacterofthe
commenttobothaperiodandan
exclamationpoint
Responsescanstillearnthepointevenif
they
useincorrectlogicinthecomparison
call String methodsincorrectly
Responseswillnotearnthepointifthey
use == insteadof equals when
comparing String objects
1point
8 Assemblesstringappropriatelybasedon
resultofcomparisonoflastcharacterwith
periodandexclamationpoint(algorithm)
Responsescanstillearnthepointevenif
they
call String methodsincorrectly
use == insteadof equals
Responseswillnotearnthepointifthey
failtokeeptrackoftheelementindex
useincorrectlogicinthecomparison
1point
9 Addsallandonlyappropriateconstructed
stringstothe ArrayList (algorithm)
Responsescanstillearnthepointevenif
they
initializethe ArrayList incorrectly
failtoreturntheconstructed
ArrayList (returnisnotassessed)
assemblethereviewstringincorrectly
accesstheelementsof allReviews
incorrectly
1point
AP®ComputerScienceA2022ScoringGuidelines
©2022CollegeBoard
Totalforpart(b) 6points
Question‐specificpenalties
None
Totalforquestion3 9points
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AP
®
Computer Science A 2022 Scoring Commentary
© 2022 College Board.
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Question 3
Note: Student samples are quoted verbatim and may contain spelling and grammatical errors.
Overview
This question tested the student’s ability to:
•
Write program code to create objects of a class and call methods.
• Write program code to satisfy method specifications using expressions, conditional statements,
and iterative statements.
• Write program code to create, traverse, and manipulate elements in 1D array and ArrayList
objects.
This question involved the traversal and manipulation of a one-dimensional (1D) array containing
Review objects and the instantiation and building of an ArrayList containing String objects.
Students were expected to write two methods in the ReviewAnalysis class, using its 1D array
instance variable, and use two methods from the Review class when accessing Review objects.
Students were also expected to use methods of the String class and construct a String object.
In part (a) students were expected to write a loop that accessed each element of the array instance
variable allReviews and returned the calculated average of all the return values of the method
getRating. Students had to declare and initialize a variable to hold the sum of all ratings. Inside
the loop, students were expected to call the method getRating on all Review elements in
allReviews, accumulating a total of the ratings. Outside the loop, students were expected to
calculate and return the average rating as a double value.
In part (b) students were asked to develop an algorithm to: (1) Identify all Review elements of
allReviews that have comments containing an exclamation point, using the getComment
method; (2) build an ArrayList of String objects, each of which would be a string based on an
identified review and formatted according to the specification:
“<index number of Review object><hyphen><comment>”
When building the formatted String to be added to the ArrayList, the specification required
that each identified formatted comment end in a period if the original comment did not already end
with a period or an exclamation point. In identifying the comments meeting the specification,
students were to use methods of the String class, such as indexOf, substring, and equals,
as well as Boolean operators.
AP
®
Computer Science A 2022 Scoring Commentary
© 2022 College Board.
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Question 3 (continued)
Sample: 3A
Score: 8
In part (a) point 1 was earned because the integer sum is initialized and then accumulated in the
body of the for loop. Point 2 was earned because all elements of the array allReviews are
accessed correctly, and there are no bounds errors. Point 3 was earned because the average is
correctly calculated and returned. The average is calculated by accumulating the sum of ratings from
all elements of allReviews. Each rating is accessed by a call to getRating on an element of
allReviews. The average is then calculated by dividing the sum, cast to a double, by the length
of the array, which represents the number of ratings.
In part (b) point 4 was earned because an ArrayList is properly instantiated to hold String
objects. Point 5 was earned because all elements of allReviews are accessed appropriately with
an indexed for loop, and there are no bounds errors. Point 6 was not earned because the call to
the indexOf method in the first if statement is not correct. The expression
allReviews[i].indexOf("!") is incorrect because the value referred to by allReviews[i] is
not a String. The correct expression would be
allReviews[i].getComment().indexOf("!"). Alternatively, the String returned by the
method call allReviews[i].getComment() could be stored in a variable and used to call
indexOf. If the indexOf call had been correct, point 6 would have been earned, even though
parentheses are missing on the call review.length – 1. The missing parentheses is one of the
minor errors for which no penalty is assessed on this exam. (See the “No Penalty” category on page
1 of the Scoring Guidelines for a complete list of such errors.) Point 7 was earned because the final
character of the comment is compared to both a period and an exclamation point using the equals
method of the String class. A correct response could also correctly extract the final character
using the charAt method of the String class, in which case comparing the final character to
both a period and an exclamation point would require char data types and the use of the == or
!= operators. Point 8 was earned because the logic of examining the final character is correct, and
an appropriate String is assembled using the correct index from the for loop. The logic is
correct in the if statement because the response checks that the final character of the comment is
not a period and is also not an exclamation point. A period is concatenated only to comments that
end with neither a period nor an exclamation point. Point 9 was earned by adding to the ArrayList
only the appropriate constructed strings, containing the required exclamation point, even though the
call to indexOf is not syntactically valid. The incorrect indexOf method call was assessed in
Point 6.
Sample: 3B
Score: 6
In part (a) point 1 was earned because the integer total is initialized and accumulated. The
omitted call to getRating is not assessed in this point. Point 2 was earned because all elements of
the array allReviews are accessed correctly, and there are no bounds errors. Point 3
was not earned because the average is not calculated using accumulated getRating return values.
The omitted getRating method call is assessed in this point.
AP
®
Computer Science A 2022 Scoring Commentary
© 2022 College Board.
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Question 3 (continued)
In part (b) point 4 was not earned because an ArrayList is not properly instantiated to
hold String objects. The angle brackets (< and >) on the left-hand side of the assignment
statement cannot be empty. The type of object to be stored in the ArrayList must be specified
within the angle brackets. When writing a method that returns an ArrayList<String>, any of the
following ArrayList declarations and instantiations would receive credit.
ArrayList list1 = new ArrayList();
ArrayList list2 = new ArrayList<>();
ArrayList list3 = new ArrayList<String>();
ArrayList<String> list4 = new ArrayList();
ArrayList<String> list5 = new ArrayList<>();
ArrayList<String> list6 = new ArrayList<String>();
ArrayList ArrayList = new ArrayList();
Point 5 was earned because all elements of allReviews are accessed correctly using an indexed
for loop, and there are no bounds errors. Point 6 was earned because the getComment method
retrieves a String from each review and stores its value in a String variable named com.
All String method calls in the response are syntactically correct. Point 7 was earned because the
final character of the String is correctly compared to both a period and an exclamation point. The
lastIndexOf method is a String method that returns the index of the last occurrence of its
parameter. Methods that are not part of the AP Java subset can be used in a response, as long as
they are used correctly. Point 8 was not earned for multiple reasons. First, the logic used to examine
the final character is incorrect; the && operator should be used instead of the || operator. As a
result of the incorrect use of ||, a period is appended to comments that end in either a period or an
exclamation point. Second, the update of an element in the ArrayList is incorrect. The statement
exM[k] = i + "-" + com + "." does not modify the value of the String in the ArrayList
and therefore no correctly constructed String exists. Either of these errors is sufficient to deem
the point unearned. Point 9 was earned because all and only appropriate constructed strings are
added to the ArrayList. Although the constructed values are not entirely correct, that error was
assessed in point 8. Point 9 can still be earned even if a response assembles the review String
incorrectly.
Sample: 3C
Score: 3
In part (a) point 1 was earned because the integer total is initialized and is accumulated in the
body of the for loop. Point 2 was earned because all elements of the array allReviews are
accessed correctly, and there are no bounds errors. The extraneous [] used when referencing the
entire allReviews array is a minor “No Penalty” error. Point 3 was earned because the average is
correctly calculated and returned. Because the accumulated sum is stored in the double variable
total, the division in the calculation of the average produces the correct double value.
In part (b) point 4 was not earned because an ArrayList is not properly instantiated to
hold String objects. The response instead attempts to declare a String array. Point 5
was not earned because the inner loop reuses the variable i. The updated value of i at the end of
AP
®
Computer Science A 2022 Scoring Commentary
Question 3 (continued)
the inner loop is used in the outer loop. This may result in some elements of allReviews being
skipped. All elements of allReviews must be accessed in order to earn this point. Point 6
was not earned because the getComment method is never called to get a String object. All the
String methods are called on Review objects rather than String objects. Point 7
was not earned because the comparisons of the final character with a period and an exclamation
point use != instead of equals. Even though the String methods are called incorrectly, the
point could have been earned if equals had been used correctly. Point 8 was not earned because
the logic used to examine the final character is incorrect; the && operator should be used instead of
the || operator to check that neither a period nor an exclamation point appears at the end of the
String. The invalid use of != is not the reason the point was not earned, as that was assessed in
point 7. Point 9 was not earned for multiple reasons. First, the use of nested loops could allow
duplicate copies of the same comment if multiple exclamation points occur in the comment. Second,
the search for the exclamation point is syntactically incorrect.
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