FRQ3 - ArrayLists

Section 15.10 FRQ3 - ArrayLists - Part 1

From the 2025 Course and Exam Description:

Free-Response Question 3: Data Analysis with ArrayList. Students will be provided with a scenario and its associated class(es). Students will write one method of a given class based on provided specifications and examples. The method requires students to use, analyze, and manipulate data in an ArrayList structure.

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FRQ 3 requires the following skills:

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Iterate through an ArrayList

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Access elements of an ArrayList

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Call methods on elements of the ArrayList

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Use a provided class

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Subsection 15.10.1 2007 FRQ3 - Student Answer Key - Part (a)

The following is a free response question from 2007. It was question 3 on the exam. You can see all the free response questions from past exams at Past AP CSA Exams.

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Question 3. Consider a system for processing student test scores. The following class will be used as part of this system and contains a student’s name and the student’s answers for a multiple-choice test. The answers are represented as strings of length one with an omitted answer being represented by a string containing a single question mark ("?"). These answers are stored in an ArrayList in which the position of the answer corresponds to the question number on the test (question numbers start at 0). A student’s score on the test is computed by comparing the student’s answers with the corresponding answers in the answer key for the test. One point is awarded for each correct answer and 1/4 of a point is deducted for each incorrect answer. Omitted answers (indicated by "?") do not change the student’s score.

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public class StudentAnswerSheet
{

    private List<String> answers;

    /** @param key the list of correct answers, represented as strings
     *         of length one
     *  Precondition: key.size() is equal to the number of answers in
     *         this answer sheet
     *  @return this student's test score
    public double getScore(List<String> key)
    {
      /* to be implemented in part (a) */
    }

    /** @return the name of the student
     */
    public String getName()
    {
       /* implementation not shown */
    }

    // There may be other fields, constructors, and methods

}

The following table shows an example of an answer key, a student’s answers, and the corresponding point values that would be awarded for the student’s answers. In this example, there are six correct answers, three incorrect answers, and one omitted answer. The student’s score is ((6 * 1) - (3 * 0.25)) = 5.25.

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Figure 15.10.1. The answer key and student answers and point values
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Part a. Write the StudentAnswerSheet method getScore. The parameter passed to method getScore is a List of strings representing the correct answer key for the test being scored. The method computes and returns a double that represents the score for the student’s test answers when compared with the answer key. One point is awarded for each correct answer and 1/4 of a point is deducted for each incorrect answer. Omitted answers (indicated by "?") do not change the student’s score.

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The code below has a main method for testing the getScore method.

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Complete method getScore below.

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Activity 15.10.1.

Complete method getScore below.

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import java.util.ArrayList;
import java.util.Arrays;

public class StudentAnswerSheet {
    /**
     * @param key the list of correct answers, represented as strings of length one Precondition:
     *     key.size() is equal to the number of answers in this answer sheet
     * @return this student's test score
     */
    public double getScore(ArrayList<String> key) {
        // *** Write this method! ***
    }

/**
     * @return the name of the student
     */
    public String getName() {
        return name;
    }

private ArrayList<String> answers; // the list of the student's answers
    private String name;

public StudentAnswerSheet(String nm, ArrayList<String> ans) {
        name = nm;
        answers = new ArrayList<String>();
        for (String a : ans) answers.add(a);
    }

public static void main(String[] args) {
        ArrayList<String> key =
                new ArrayList<String>(
                        Arrays.asList(
                                new String[] {"A", "C", "D", "E", "B", "C", "E", "B", "B", "C"}));

ArrayList<String> answers1 =
                new ArrayList<String>(
                        Arrays.asList(
                                new String[] {"A", "B", "D", "E", "A", "C", "?", "B", "D", "C"}));
        StudentAnswerSheet s1 = new StudentAnswerSheet("S1", answers1);
        System.out.println("Your score for s1 is: " + s1.getScore(key) + " and should be 5.25");

ArrayList<String> answers2 =
                new ArrayList<String>(
                        Arrays.asList(
                                new String[] {"A", "?", "D", "E", "A", "C", "?", "B", "D", "C"}));
        StudentAnswerSheet s2 = new StudentAnswerSheet("S2", answers2);
        System.out.println("Your score for s2 is: " + s2.getScore(key) + " and should be 5.5");

ArrayList<String> answers3 =
                new ArrayList<String>(
                        Arrays.asList(
                                new String[] {"A", "?", "D", "E", "A", "C", "E", "B", "D", "C"}));
        StudentAnswerSheet s3 = new StudentAnswerSheet("S3", answers3);
        System.out.println("Your score for s3 is: " + s3.getScore(key) + " and should be 6.5");

ArrayList<String> answers4 =
                new ArrayList<String>(
                        Arrays.asList(
                                new String[] {"A", "C", "D", "E", "A", "C", "E", "B", "D", "C"}));
        StudentAnswerSheet s4 = new StudentAnswerSheet("S4", answers4);
        System.out.println("Your score for s4 is: " + s4.getScore(key) + " and should be 7.5");
    }
}
====

import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;

public class RunestoneTests extends CodeTestHelper {
    public RunestoneTests() {
        super("StudentAnswerSheet");
        // CodeTestHelper.sort = true;
    }

@Test
    public void testMain1() {
        boolean passed = false;

String expect =
                "Your score for s1 is: 5.25 and should be 5.25\n"
                        + "Your score for s2 is: 5.5 and should be 5.5\n"
                        + "Your score for s3 is: 6.5 and should be 6.5\n"
                        + "Your score for s4 is: 7.5 and should be 7.5";

String output = getMethodOutput("main");

passed = getResults(expect, output, "Checking for expected output");
        assertTrue(passed);
    }

@Test
    public void testMain2() {
        boolean passed = false;

String keyList = "A A A B B B C C C D D D E E E";
        String ansList = "A B ? B C ? C D ? D E ? E A ?";

ArrayList<String> key = new ArrayList<String>(Arrays.asList(keyList.split(" ")));

ArrayList<String> answers1 = new ArrayList<String>(Arrays.asList(ansList.split(" ")));

StudentAnswerSheet s1 = new StudentAnswerSheet("S1", answers1);

String output = "Your score for s1 is: " + s1.getScore(key);

String expect = "Your score for s1 is: 3.75";

passed = getResults(expect, output, "Checking for expected output");
        assertTrue(passed);
    }
}

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Subsection 15.10.2 2007 FRQ3 - Student Answer Key - Part (b)

Part b. Consider the following class that represents the test results of a group of students that took a multiple-choice test.

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public class TestResults {
    private List<StudentAnswerSheet> sheets;

    /**
     * Precondition: sheets.size() > 0; all answer sheets in sheets have the same number of answers
     *
     * @param key the list of correct answers represented as strings of length one Precondition:
     *     key.size() is equal to the number of answers in each of the answer sheets in sheets
     * @return the name of the student with the highest score
     */
    public String highestScoringStudent(List<String> key) {
        /* to be implemented in part (b) */
    }

    // There may be fields, constructors, and methods that are not shown.
}

Write the TestResults method highestScoringStudent, which returns the name of the student who received the highest score on the test represented by the parameter key. If there is more than one student with the highest score, the name of any one of these highest-scoring students may be returned. You may assume that the size of each answer sheet represented in sheets is equal to the size of key.

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Complete method highestScoringStudent below.

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The code below has a main method for testing the highestScoringStudent method.

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Activity 15.10.2.

Complete method highestScoringStudent below.

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import java.util.ArrayList;
import java.util.Arrays;

public class TestResults {
    private ArrayList<StudentAnswerSheet> sheets;

/**
     * Precondition: sheets.size() > 0; all answer sheets in sheets have the same number of answers
     *
     * @param key the list of correct answers represented as strings of length one Precondition:
     *     key.size() is equal to the number of answers in each of the answer sheets in sheets
     * @return the name of the student with the highest score
     */
    public String highestScoringStudent(ArrayList<String> key) {
        // *** Write this method! ***
    }

ArrayList<StudentAnswerSheet> sheets = new ArrayList<StudentAnswerSheet>();
        sheets.add(s1);
        sheets.add(s2);
        sheets.add(s3);
        sheets.add(s4);

TestResults results = new TestResults(sheets);
        System.out.println(
                "Your best is: " + results.highestScoringStudent(key) + " and should be S4");
    }

public TestResults(ArrayList<StudentAnswerSheet> shs) {
        sheets = new ArrayList<StudentAnswerSheet>();
        for (StudentAnswerSheet s : shs) sheets.add(s);
    }
}

class StudentAnswerSheet {
    private ArrayList<String> answers; // the list of the student's answers
    private String name;

public StudentAnswerSheet(String nm, ArrayList<String> ans) {
        name = nm;
        answers = new ArrayList<String>();
        for (String a : ans) answers.add(a);
    }

/**
     * @param key the list of correct answers, represented as strings of length one Precondition:
     *     key.size() is equal to the number of answers in this answer sheet
     * @return this student's test score
     */
    public double getScore(ArrayList<String> key) {
        double score = 0;
        for (int i = 0; i < key.size(); i++) {
            if (key.get(i).equals(answers.get(i))) {
                score = score + 1.0;
            } else if (!answers.get(i).equals("?")) {
                score = score - 0.25;
            }
        }
        return score;
    }

/**
     * @return the name of the student
     */
    public String getName() {
        return name;
    }
}
====

import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;

public class RunestoneTests extends CodeTestHelper {
    public RunestoneTests() {
        super("TestResults");
        // CodeTestHelper.sort = true;
    }

@Test
    public void testMain1() {
        boolean passed = false;

String output = getMethodOutput("main");

passed = getResults(expect, output, "Checking for expected output");
        assertTrue(passed);
    }

@Test
    public void testMain2() {
        boolean passed = false;

String keyList = "A A A B B B C C C D D D E E E";
        String ansList1 = "A B ? B C ? C D ? D E ? E A ?";
        String ansList2 = "A B D B C D C D B D E C E A B";
        String ansList3 = "A A A B B B C C C D D D E E E";
        String ansList4 = "B B B B B B C C C C C C E E E";

ArrayList<String> key = new ArrayList<String>(Arrays.asList(keyList.split(" ")));

ArrayList<String> answers1 = new ArrayList<String>(Arrays.asList(ansList1.split(" ")));
        ArrayList<String> answers2 = new ArrayList<String>(Arrays.asList(ansList2.split(" ")));
        ArrayList<String> answers3 = new ArrayList<String>(Arrays.asList(ansList3.split(" ")));
        ArrayList<String> answers4 = new ArrayList<String>(Arrays.asList(ansList4.split(" ")));

StudentAnswerSheet s1 = new StudentAnswerSheet("S1", answers1);
        StudentAnswerSheet s2 = new StudentAnswerSheet("S2", answers2);
        StudentAnswerSheet s3 = new StudentAnswerSheet("S2", answers3);
        StudentAnswerSheet s4 = new StudentAnswerSheet("S2", answers4);

ArrayList<StudentAnswerSheet> sheets = new ArrayList<StudentAnswerSheet>();
        sheets.add(s1);
        sheets.add(s2);
        sheets.add(s3);
        sheets.add(s4);

TestResults results = new TestResults(sheets);

// change this next line
        String output = "Your best is: " + results.highestScoringStudent(key);

String expect = "Your best is: S2";

passed = getResults(expect, output, "Checking for expected output");
        assertTrue(passed);
    }
}

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