15.6. StudentAnswerSheet - Part B¶

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

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.

15.6.1. Try and Solve It¶

Complete method highestScoringStudent below.

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

Complete method highestScoringStudent below.

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

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

public StudentAnswerSheet(String nm, List<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;
    }
}

public class TestResults
{
    private ArrayList<StudentAnswerSheet> sheets;

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

/**
     * 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! ***
    }

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");

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");
    }
}

====
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 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\n"
                    + "Your best is: S4 and should be S4";

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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