Free Response Questions

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Java1 class period5 exercises19 graded tests

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Free Response Questions

Each coding exercise has its own folder. Open its .java file and press Run to try it. Run Tests checks every graded exercise in this lesson at once.

Free Response - Trio A

The following is a free response question from 2014. It was question 4 on the exam. You can see all the free response questions from past exams at Past AP CSA Exams.

Question 4. The menu at a lunch counter includes a variety of sandwiches, salads, and drinks. The menu also allows a customer to create a “trio,” which consists of three menu items: a sandwich, a salad, and a drink. The price of the trio is the sum of the two highest-priced menu items in the trio; one item with the lowest price is free. Each menu item has a name and a price. The four types of menu items are represented by the four classes Sandwich, Salad, Drink, and Trio. All four classes implement the following MenuItem interface.

Interfaces are no longer on the AP CSA exam, but you can just treat an interface like a superclass. Just substitute the word class instead of interface below and your TrioClass can extend MenuItem instead of implementing the interface.

public interface MenuItem
{
    /**
     * @return the name of the menu item
     */
    String getName();

    /**
     * @return the price of the menu item
     */
    double getPrice();
}

The following diagram shows the relationship between the MenuItem interface and the Sandwich, Salad, Drink, and Trio classes.

UML class diagram showing MenuItem is implemented by Sandwich, Salad, Drink, and Trio.

UML class diagram showing MenuItem is implemented by Sandwich, Salad, Drink, and Trio.

For example, assume that the menu includes the following items. The objects listed under each heading are instances of the class indicated by the heading.

Example objects

Example objects

The menu allows customers to create Trio menu items, each of which includes a sandwich, a salad, and a drink. The name of the Trio consists of the names of the sandwich, salad, and drink, in that order, each separated by “/” and followed by a space and then “Trio”. The price of the Trio is the sum of the two highest-priced items in the Trio; one item with the lowest price is free. A trio consisting of a cheeseburger, spinach salad, and an orange soda would have the name "Cheeseburger/Spinach Salad/Orange Soda Trio" and a price of $4.00 (the two highest prices are $2.75 and $1.25). Similarly, a trio consisting of a club sandwich, coleslaw, and a cappuccino would have the name "Club Sandwich/Coleslaw/Cappuccino Trio" and a price of $6.25 (the two highest prices are $2.75 and $3.50).

Try and Solve It

Exercise 1

Write the Trio class (near the end of the code) that implements the MenuItem interface (which is like extending a class). Your implementation must include a constructor that takes three parameters representing a sandwich, salad, and drink. The main method has code to test the result.

Open the 01-frqTrio folder and edit Trio.java. Press Run to try it; Run Tests checks it (7 tests).

Trio Student Solution 1

The following is a free response question from 2014. It was question 4 on the exam. You can see all the free response questions from past exams at Past AP CSA Exams.

public interface MenuItem
{
    /**
     * @return the name of the menu item
     */
    String getName();

    /**
     * @return the price of the menu item
     */
    double getPrice();
}

The following diagram shows the relationship between the MenuItem interface and the Sandwich, Salad, Drink, and Trio classes.

UML class diagram showing MenuItem is implemented by Sandwich, Salad, Drink, and Trio.

UML class diagram showing MenuItem is implemented by Sandwich, Salad, Drink, and Trio.

For example, assume that the menu includes the following items. The objects listed under each heading are instances of the class indicated by the heading.

Example objects

Example objects

Grading Rubric

Below is the grading rubric for the Trio class problem.

The grading rubric for the Trio class problem.

The grading rubric for the Trio class problem.

Practice Grading

The following is the first sample student response.

The first sample student response to the Trio class problem.

The first sample student response to the Trio class problem.

Apply the grading rubric shown above as you answer the following questions.

Apply the Grading Rubric

Check your understanding: Should the student earn 1 point for the correct declaration of the Trio class? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_1

Check your understanding: Should the student earn 1 point for declaring the private instance variables (sandwich, salad, and drink or name and price)? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_2

Check your understanding: Should the student earn 1 point for declaring the constructor correctly? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_3

Check your understanding: Should the student earn 1 point for correctly initializing the appropriate instance variables in the constructor? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_4

Check your understanding: Should the student earn 1 point for correctly declaring the methods in the MenuItem interface (getName and getPrice)? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_5

Check your understanding: Should the student earn 1 point for correctly constructing the string to return from getName and making it available to be returned? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_6

Check your understanding: Should the student earn 1 point for returning a constructed string from getName? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_7

Check your understanding: Should the student earn 1 point for correctly calculating the price and making it available to be returned from getPrice? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_8

Check your understanding: Should the student earn 1 point for returning the calculated price in getPrice? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_9

Check your understanding: What should the total score be for this student response (out of 9 points)? Enter it as a number (like 3). — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio1_total

Trio Student Solution 2

The following is a free response question from 2014. It was question 4 on the exam. You can see all the free response questions from past exams at Past AP CSA Exams.

public interface MenuItem
{
    /**
     * @return the name of the menu item
     */
    String getName();

    /**
     * @return the price of the menu item
     */
    double getPrice();
}

The following diagram shows the relationship between the MenuItem interface and the Sandwich, Salad, Drink, and Trio classes.

UML class diagram showing MenuItem is implemented by Sandwich, Salad, Drink, and Trio.

UML class diagram showing MenuItem is implemented by Sandwich, Salad, Drink, and Trio.

For example, assume that the menu includes the following items. The objects listed under each heading are instances of the class indicated by the heading.

Example objects

Example objects

Grading Rubric

Below is the grading rubric for the Trio class problem.

The grading rubric for the Trio class problem.

The grading rubric for the Trio class problem.

Practice Grading

The following is the second sample student response.

The start of the second sample student response to the Trio class problem.

The start of the second sample student response to the Trio class problem.

The end of the second sample student response to the Trio class problem.

The end of the second sample student response to the Trio class problem.

Apply the grading rubric shown above as you answer the following questions.

Apply the Grading Rubric

Check your understanding: Should the student earn 1 point for the correct declaration of the Trio class? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_1

Check your understanding: Should the student earn 1 point for declaring the private instance variables (sandwich, salad, and drink or name and price)? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_2

Check your understanding: Should the student earn 1 point for declaring the constructor correctly? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_3

Check your understanding: Should the student earn 1 point for correctly initializing the appropriate instance variables in the constructor? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_4

Check your understanding: Should the student earn 1 point for correctly declaring the methods in the MenuItem interface (getName and getPrice)? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_5

Check your understanding: Should the student earn 1 point for correctly constructing the string to return from getName and making it available to be returned? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_6

Check your understanding: Should the student earn 1 point for returning a constructed string from getName? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_7

Check your understanding: Should the student earn 1 point for correctly calculating the price and making it available to be returned from getPrice? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_8

Check your understanding: Should the student earn 1 point for returning the calculated price in getPrice? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_9

Check your understanding: What should the total score be for this student response (out of 9 points)? Enter it as a number (like 3). — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio2_total

Trio Student Solution 3

The following is a free response question from 2014. It was question 4 on the exam. You can see all the free response questions from past exams at Past AP CSA Exams.

public interface MenuItem
{
    /**
     * @return the name of the menu item
     */
    String getName();

    /**
     * @return the price of the menu item
     */
    double getPrice();
}

The following diagram shows the relationship between the MenuItem interface and the Sandwich, Salad, Drink, and Trio classes.

UML class diagram showing MenuItem is implemented by Sandwich, Salad, Drink, and Trio.

UML class diagram showing MenuItem is implemented by Sandwich, Salad, Drink, and Trio.

For example, assume that the menu includes the following items. The objects listed under each heading are instances of the class indicated by the heading.

Example objects

Example objects

Grading Rubric

Below is the grading rubric for the Trio class problem.

The grading rubric for the Trio class problem.

The grading rubric for the Trio class problem.

Practice Grading

The following is the third sample student response.

The start of the second sample student response to the Trio class problem.

The start of the second sample student response to the Trio class problem.

Apply the grading rubric shown above as you answer the following questions.

Apply the Grading Rubric

Check your understanding: Should the student earn 1 point for the correct declaration of the Trio class? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_1

Check your understanding: Should the student earn 1 point for declaring the private instance variables (sandwich, salad, and drink or name and price)? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_2

Check your understanding: Should the student earn 1 point for declaring the constructor correctly? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_3

Check your understanding: Should the student earn 1 point for correctly initializing the appropriate instance variables in the constructor? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_4

Check your understanding: Should the student earn 1 point for correctly declaring the methods in the MenuItem interface (getName and getPrice)? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_5

Check your understanding: Should the student earn 1 point for correctly constructing the string to return from getName and making it available to be returned? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_6

Check your understanding: Should the student earn 1 point for returning a constructed string from getName? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_7

Check your understanding: Should the student earn 1 point for correctly calculating the price and making it available to be returned from getPrice? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_8

Check your understanding: Should the student earn 1 point for returning the calculated price in getPrice? — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_9

Check your understanding: What should the total score be for this student response (out of 9 points)? Enter it as a number (like 3). — answer it on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html#qtrio3_total

Retired FRQ - Inheritance - NumberGroup - Part B

Part b. A range represents a number group that contains all (and only) the integers between a minimum value and a maximum value, inclusive. Write the Range class, which is a NumberGroup. The Range class represents the group of int values that range from a given minimum value up through a given maximum value, inclusive. For example, the declaration NumberGroup range1 = new Range(-3, 2); represents the group of integer values -3, -2, -1, 0, 1, 2.

Write the complete Range class. Include all necessary instance variables and methods as well as a constructor that takes two int parameters. The first parameter represents the minimum value, and the second parameter represents the maximum value of the range. You may assume that the minimum is less than or equal to the maximum. Write the contains method which returns true or false if a given int argument is within the range set up by the constructor.

Try and Solve It

Exercise 2

Complete the class Range with instance variables, a constructor, and a contains method.

Open the 02-NumberGroupB folder and edit Range.java. Press Run to try it; Run Tests checks it (3 tests).

Retired FRQ - Inheritance - NumberGroup - Part C

Part c. The MultipleGroups class represents a collection of NumberGroup objects and is a NumberGroup. The MultipleGroups class stores the number groups in the instance variable groupList (shown below), which is initialized in the constructor.

private ArrayList<NumberGroup> groupList;

Write the MultipleGroups method contains. The method takes an integer and returns true if and only if the integer is contained in one or more of the number groups in groupList.

For example, suppose multiple1 has been declared as an instance of MultipleGroups and consists of the three ranges created by the calls:

new Range(5, 8)
new Range(10, 12)
new Range(1, 6)

The following table shows the results of several calls to contains.

Number Group

Try and Solve It

Exercise 3

Write the method contains in the class MultiGroups. (Note that the original AP Question involved a NumberGroup interface which has been replaced with inheritance here).

Open the 03-NumberGroupC folder and edit MultiGroups.java. Press Run to try it; Run Tests checks it (3 tests).

Retired FRQ - Arrays - ArrayTester - Part A

The following is a free response question from 2018. It was question 4 on the exam. You can see all the free response questions from past exams at Past AP CSA Exams.

Question 4. This question involves reasoning about arrays of integers. You will write two static methods, both of which are in a class named ArrayTester.

public class ArrayTester
{
    /**
     * Returns an array containing the elements of column c of arr2D in the same
     * order as they appear in arr2D. Precondition: c is a valid column index in
     * arr2D. Postcondition: arr2D is unchanged.
     */
    public static int[] getColumn(int[][] arr2D, int c)
    {
        /* to be implemented in part (a) */
    }

    /**
     * Returns true if and only if every value in arr1 appears in arr2.
     * Precondition: arr1 and arr2 have the same length. Postcondition: arr1 and
     * arr2 are unchanged.
     */
    public static boolean hasAllValues(int[] arr1, int[] arr2)
    {
        /* implementation not shown */
    }

    /** Returns true if arr contains any duplicate values; false otherwise. */
    public static boolean containsDuplicates(int[] arr)
    {
        /* implementation not shown) */
    }

    /**
     * Returns true if square is a Latin square as described in part (b); false
     * otherwise. Precondition: square has an equal number of rows and columns.
     * Precondition: square has at least one row.
     */
    public static boolean isLatin(int[][] square)
    {
        /* to be implemented in part (b) */
    }
}

Part a. Write a static method getColumn, which returns a one-dimensional array containing the elements of a single column in a two-dimensional array. The elements in the returned array should be in the same order as they appear in the given column. The notation arr2D [r][c] represents the array at row r and column c.

The following code segment initializes an array and calls the getColumn method.

int [] [] arr2D = { { 0, 1, 2 }, { 3, 4, 5 }, { 6, 7, 8 }, { 9, 5, 3 }};
int[] result = ArrayTester.getColumn (arr2D, 1);

When the code segment has completed execution, the variable result result will have the following contents. result: {1, 4, 7, 5}

Try and Solve It

Exercise 4

Complete the method getColumn.

Open the 04-getColumn folder and edit ArrayTester.java. Press Run to try it; Run Tests checks it (3 tests).

Retired FRQ - Arrays - ArrayTester - Part B

Arrays are no longer part of an assigned FRQ. However, they are good practice with reading and answering FRQs.

Part b. Write the static method isLatin, which returns true if a given two-dimensional square array is a Latin square, and otherwise, returns false.

A two-dimensional square array of integers is a Latin square if the following conditions are true. 1) The first row has no duplicate values. 2) All values in the first row of the square appear in each row of the square. 3) All values in the first row of the square appear in each column of the square.

Latin Square Ex

The ArrayTester class provides two helper methods: containsDuplicates and hasAllValues. The method containsDuplicates returns true if the given one-dimensional array arr contains any duplicate values and false otherwise. The method hasAllValues returns true if and only if every value in arr1 appears in arr2. You do not need to write the code for these methods.

Latin Square Ex2

Complete method isLatin below. Assume that getColumn works as specified, regardless of what you wrote in part (a). You must use getColumn, hasAllValues, and containsDuplicates appropriately to receive full credit.

Try and Solve It

Exercise 5

Complete the method isLatin.

Open the 05-isLatinTwo folder and edit ArrayTester.java. Press Run to try it; Run Tests checks it (3 tests).

For teachers

Free Response Questions

Students read CSAwesome2's “Free Response Questions” in CS Room and work through its 5 Java coding exercises.

Time: 1 class period
Tests: 19 in 5 graded exercises, set up for you when you import the lesson

Goals

Practice for Unit 5: Inheritance (optional).

Before class

Import the lesson into your class from the Lessons page, or with New assignment → Use a lesson. It arrives as a draft with its tests already set up.
Publish it.
The original page, with its fill-in and multiple-choice questions, is on CS Awesome: https://runestone.academy/ns/books/published/csawesome2/free-response-questions.html
CS Awesome's own teacher materials: the CS Awesome teacher site

In class

Students read README.md. Questions that need CS Awesome's interactive widgets link back to it.
Students do exercises 01–05, each in its own folder, pressing Run to try their code.
Run Tests checks every graded exercise at once; scores appear in the Gradebook. Grading uses your copy of the tests, so a student who edits theirs does not change the grade.

Exercises

Folder	File	Grading	Tests
`01-frqTrio`	`Trio.java`	Autograded	7
`02-NumberGroupB`	`Range.java`	Autograded	3
`03-NumberGroupC`	`MultiGroups.java`	Autograded	3
`04-getColumn`	`ArrayTester.java`	Autograded	3
`05-isLatinTwo`	`ArrayTester.java`	Autograded	3

Teachers can download a reference solution after signing in.