Question

The following is the class definition for Multiplier. This class has five (5) members:

• two private instance variables
• two private methods
• one public method
  • this is only public method for the class
  • it calls other two private methods

import java.util.*; //We need to use Scanner & Random in this package public class Multiplier {        private int answer; //for holding the correct answer        private Random randomNumbers = new Random(); //for creating random numbers        //ask the user to work on multiplication problems, a starter        public void quiz() {               int guess; //for holding the user's guess               Scanner input = new Scanner(System.in);               createQuestion();               do {                      System.out.println("Enter your answer or -1 to exit: ");                      guess = input.nextInt();                      if (guess == -1) {                            System.out.println("You have decided to exit!");                            break;                      }                      checkResponse(guess);               } while (guess != answer);        } //end quiz method        //print a new question and store the corresponding answer        private void createQuestion() {               //get two random numbers between 0 and 9, inclusively               int digit1 = randomNumbers.nextInt(10);               int digit2 = randomNumbers.nextInt(10);               answer = digit1 * digit2;               System.out.printf("How much is %d times %d?\n", digit1, digit2);        } //end createQuestion method        //check if the user has answered correctly        private void checkResponse(int guess) {               if (guess == answer) {                      System.out.println("Very good!\n");                      createQuestion();               }               else {                      System.out.println("Wrong answer! Try again!");               }        } //end checkResponse method } //end class Multiplier

Write a Java application to invoke the quiz defined in this class. Note: please write the program in a compact form since there are only six text lines in the answer area.

Answer 1

PROGRAM :

Multiplier.java

import java.util.*;

public class Multiplier {

private int answer;

private Random randomNumbers = new Random();

public void quiz(){

int guess;

Scanner input = new Scanner(System.in);

createQuestion();

do{

System.out.println("Enter your answer or -1 to exit: ");

guess = input.nextInt();

if(guess==-1){

System.out.println("You have decided to exit!");

break;

}

checkResponse(guess);

}while(guess!=answer);

}

private void createQuestion(){

int digit1 = randomNumbers.nextInt(10);

int digit2 = randomNumbers.nextInt(10);

answer = digit1 * digit2;

System.out.printf("How much is %d times %d?\n", digit1, digit2);

}

private void checkResponse(int guess){

if(guess==answer){

System.out.println("Very good!\n");

createQuestion();

}

else{

System.out.println("Wrong answer! Try again!");

}

}

}

MultiplierDemo.java

public class MultiplierDemo {

public static void main(String[] args) {

Multiplier mul = new Multiplier();

mul.quiz();

}

}

OUTPUT :

How much is 8 times 6? Enter your answer or -1 to exit: 48 Very good! How much is 9 times 6? Enter your answer or -1 to exit: 65 Wrong answer! Try again! Enter your answer or -1 to exit: 54 Very good! How much is 1 times 2? Enter your answer or -1 to exit: -1 You have decided to exit!