Question

According to the given UML class diagram and classes, complete the missing part of the given program by using polymorphism in the main method.

In the main method there are:

• 3 question instances,
• 1 arraylist for multiple choice answers,
• 1 arraylist for fill in the blanks answers created.

1. Add those objects to a collection and process the collection. During processing:
2. display the correctAnswer for each question.
3. add the answer to the correct collection: selectionAnswers/textAnswers
4. Specify where the polymorphic behaviours are used in your code. (use comments)

Source Code:

import java.util.ArrayList;

abstract class Question {
   String question, correctAnswer;

   public Question(String question, String correctAnswer) {
       super();
       this.question = question;
       this.correctAnswer = correctAnswer;
   }
}

class FillInTheBlank extends Question {

   public FillInTheBlank(String question, String correctAnswer) {
       super(question, correctAnswer);
   }

   public String getCorrectAnswer() {
       return correctAnswer;
   }

}

class MultipleChoice extends Question {
   String choices[];

   public MultipleChoice(String question, String correctAnswer, String choice1, String choice2, String choice3,
           String choice4) {
       super(question, correctAnswer);
       String choices[] = { choice1, choice2, choice3, choice4 };
       this.choices = choices;
   }

   public char getCorrectChoice() {
       int i;
       int a = 65; // 'A'
       char c = 'A';
       for (i = 0; i < choices.length; i++) {
           if (choices[i].equals(correctAnswer)) {
               c = (char) (a + i);
               break;
           }
       }
       return c;
   }
}

public class Test {

   public static void main(String[] args) {
       MultipleChoice q1 = new MultipleChoice("2+1=?", "3", "2", "3", "4", "5");
       FillInTheBlank q2 = new FillInTheBlank("3 is _____ number.", "an odd");
       FillInTheBlank q3 = new FillInTheBlank("2+2=___", "4");

       ArrayList<Character> selectionAnswers = new ArrayList<Character>();
       ArrayList<String> textAnswers = new ArrayList<String>();

       // Add your code here

       Question test[] = { q1, q2, q3 };
       for (int i = 0; i < test.length; i++) {
           System.out.println(test[i].correctAnswer);
           if (test[i] instanceof MultipleChoice) {
               char answer = ((MultipleChoice) test[i]).getCorrectChoice();
               selectionAnswers.add(answer);
           }
           if (test[i] instanceof FillInTheBlank) {
               String answer = ((FillInTheBlank) test[i]).getCorrectAnswer();
               textAnswers.add(answer);
           }
       }

       System.out.println();
       System.out.println(selectionAnswers.toString());
       System.out.println(textAnswers.toString());
   }
}

Answer 1

Ans Code: Test.java

package com.app;

import java.util.ArrayList;

abstract class Question {
String question, correctAnswer;

public Question(String question, String correctAnswer) {
super();
this.question = question;
this.correctAnswer = correctAnswer;
}
}

class FillInTheBlank extends Question {

public FillInTheBlank(String question, String correctAnswer) {
super(question, correctAnswer);
}

public String getCorrectAnswer() {
return correctAnswer;
}

public String toString(){
     
     
   return "FillInTheBlank["+question+":"+correctAnswer+"]";
}

}

class MultipleChoice extends Question {
String choices[];

public MultipleChoice(String question, String correctAnswer, String choice1, String choice2, String choice3,
String choice4) {
super(question, correctAnswer);
String choices[] = { choice1, choice2, choice3, choice4 };
this.choices = choices;
}

//this method returns 'B' because 65+1(1st index matching) and cast to char is 'B'
public char getCorrectChoice() {
int i;
int a = 65; // 'A'
char c = 'A';
for (i = 0; i < choices.length; i++) {
if (choices[i].equals(correctAnswer)) {
c = (char) (a + i);
break;
}
}
return c;
}

public String toString(){
     
     
   return "MultipleChoice["+question+":"+correctAnswer+"]";
}


}

public class Test {

public static void main(String[] args) {
MultipleChoice q1 = new MultipleChoice("2+1=?", "3", "2", "3", "4", "5");
FillInTheBlank q2 = new FillInTheBlank("3 is _____ number.", "an odd");
FillInTheBlank q3 = new FillInTheBlank("2+2=___", "4");

ArrayList<Character> selectionAnswers = new ArrayList<Character>();
ArrayList<String> textAnswers = new ArrayList<String>();

// Add your code here
//Here Question is an Parent class and q1,q2,q3 are childs to the Question class
//child objects are referring by using parent reference
Question test[] = { q1, q2, q3 };
for (int i = 0; i < test.length; i++) {
System.out.println(test[i].correctAnswer);
if (test[i] instanceof MultipleChoice) {
char answer = ((MultipleChoice) test[i]).getCorrectChoice();
selectionAnswers.add(answer);
}
if (test[i] instanceof FillInTheBlank) {
String answer = ((FillInTheBlank) test[i]).getCorrectAnswer();
textAnswers.add(answer);
}
}

System.out.println();
System.out.println(selectionAnswers.toString());
System.out.println(textAnswers.toString());
}
}

Output:

X Problems @ Javadoc Declaration Console X <terminated Test [Java Application] C:\Program Files Vavaljdk1.8.0_181\bin\javaw.exe (May 4, 2020, 9:53:48 PM) an odd [B] [an odd, 4]

X Problems @ Javadoc Declaration Console X <terminated Test [Java Application] C:\Program Files Vavaljdk1.8.0_181\bin\javaw.exe (May 4, 2020, 9:53:48 PM) an odd [B] [an odd, 4]