Quizard

step-by-step

Start with the questions

• The Question class is abstract– a Superclass

• You’ll never create something that’s just a question.

• It’ll always be a specific type of question

Top-Down Design:refinement

Questions —

Classes that represent different types of questions.

«abstract»Question

MCQuestion TFQuestion

FRQuestion

TestQuestion

Create a test case for testing in isolation

Question class

• What does every question have?• These are the kinds of questions:

1. multiple choice2. true/false3. and free response

• They all have:– the words describing the question (including a

description of answer choices if appropriate)– correct answer– point value

constructor

• Always 3 parameters given:– question, answer and number of points are all

initialized when the question is created.

• never changed.

• don’t need mutators

• only accessors

«abstract»Question

String questionString answer

int points

MCQuestion TFQuestion

FRQuestion

What methods do all questions have in common?

Accessors:

getQuestion()

getAnswer()

getPoints()

A way to display the question

toString()

/** * Compare this question's correct answer with the entered answer * @param userAns the entered answer (in upper case) * @return 1 if userAns matches this question's answer, 0 if there is no match, * and -1 if userAns is invalid */ public abstract int compareAns(String ans);

Each subclass must define compareAns for that particular type of question.

NOT defined in Question

Fill in the code for the Question class

Accessors:

getQuestion()

getAnswer()

getPoints()

A way to display the question

toString()

abstract method

public abstract int compareAns(String ans);

«abstract»Question

String questionTextString answerText

int numPoints

«abstract»Question

String questionTextString answerText

int numPoints

MCQuestion

ArrayList ansOpts

TFQuestion

FRQuestion

How are the question subclasses unique?

Answer Options:

MC = ArrayList of choices

TF = always T/F, part of the question text

FR = no answer option given, user must enter

Some way to display the question

toString(), same for TF and MC, different for MC

/** * Compare this question's correct answer with the entered answer*/ public int compareAns(String ans)MC = user enters a letter, must be A-F (ignore case) compare to correct letter answerTF = user enters a letter, must be T or F, compare to correct letter answerFR= user enters words, to keep it simple, only an exact match counts (ignoring case)

Examples TF

From the text file:

TF 3Q: True or false: The chicken crossed the road to get to the other sideA: T

Question tester = new TFQuestion(“True or false: The chicken crossed the road to get to the other side”, “T”,3);

tester.getPoints(); // = 3 inherited from Question

tester.compareAnswer(“F”); // = 0, doesn’t match, TF method

tester.getAnswer(); // = “T” inherited from Question

«abstract»Question

String questionTextString answerText

int numPoints

TFQuestion

only code needed for TF• constructor: call the superclass, assume you are given question,

answer and points as parameters to the constructor.

• public int compareAns(String userAns)• {• if they didn’t answer T or F• return -1; // Invalid answer• else if the user answer = the correct answer• return 1; // correct• else• return 0; // incorrect• }

make TFQuestion

«abstract»Question

String questionTextString answerText

int numPoints

TFQuestion

Examples FR

From the text file:

FR 3Q: Name a random integer between 2.5 and 3.5A: 3

Question tester = new FRQuestion(“Name a random integer between 2.5 and 3.5”, “3”,3);

tester.getPoints(); // = 3

tester.compareAnswer(“8”); // = 0, doesn’t match

tester.getAnswer(); // = “3”

only code needed for FR

• constructor: call the superclass, assume you are given question, answer and points as parameters to the constructor.

• public int compareAns(String userAns)• {• if the user answer = the correct answer

(ignoring any differences in case)• return 1; // correct• else• return 0; // incorrect• }

make FRQuestion

«abstract»Question

String questionTextString answerText

int numPoints

FRQuestion

Examples MCFrom the text file:

MC 8Q: What is encapsulation? A. Being abducted by a UFO B. A 20-second news report on MSNBC C. Calling String's toUpperCase() D. Making all data members of a class privateA: D

When constructing a MC question public MCQuestion(String qtn, ArrayList options, String ans, int pts) { call the superclass constructor to make a question setting qtn, ans and pts instantiate the arraylist for this object copy all the items in the options arraylist into the instance variable arraylist }

MCQuestion

ArrayList ansOpts

write the constructor for a MCQuestion

getQuestion for MCoverrides getQuestion in Question

MCQuestion

ArrayList ansOpts

public String getQuestion() {String str; start by calling getQuestion() from superclass and adding an end-of-line character to it to create the string. for (a counter goes from 0 to the size of the ansOpts arraylist) get the next ansOpt, add it to str with an end-of-line mark at the end of each. return str; }

write the getQuestion method for a MCQuestion

• public int compareAns(String userAns)• {• if (the user answer is more than one letter long)• return -1; // invalid

• if (the user answer is not a letter from A to E)• return -1; // invalid

• if (the user answer is the same as the question answer)• return 1; // correct• else• return 0; // incorrect• }

Write the compareAns method for MCQuestion

Test the questionsimport java.util.ArrayList;

public class TestQuestion{ public static void main(String[] args) { System.out.println("Testing Questions...\n");

/* Free-response question */

Question fr = new FRQuestion("What kind of question is this?", "FR", 7); System.out.println(fr); System.out.println("Compare answers (should be 0 1): " + fr.compareAns("XYZ") + " " + fr.compareAns("FR")); System.out.println();

/* True or false question */

Question tf = new TFQuestion("This is a true/false Question", "T", 5);

System.out.println(tf); System.out.println("Compare answers (should be -1 0 1): " + tf.compareAns("X") + " " + tf.compareAns("F") + " " + tf.compareAns("T")); System.out.println();

/* Multiple-choice question */

ArrayList options = new ArrayList(); options.add(" A. Free response"); options.add(" B. Multiple choice"); options.add(" C. True/false"); MCQuestion mc = new MCQuestion("What kind of question is this?", options, "B", 10); System.out.println(mc); System.out.println("Compare answers (should be -1 0 1): " + mc.compareAns("X") + " " + mc.compareAns("C") + " " + mc.compareAns("B")); System.out.println(); }

Test ReaderWhy test it? To take the time to look at the code and

methods used in reading the input file to understand them.

• public class TestReader• {• public static void main(String[] args)• {• QuizReader reader = new QuizReader("test.dat");

• Question qtn;• while ((qtn = reader.nextQuestion()) != null)• System.out.println(qtn);• }• }