Case Study II - Solution

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Introduction This is the solution page for Case Study II. Here you will find the sample solution code to the problem, as well as an explanation of how to arrive at this solution. The information required to complete this case study can be found in the chapters previous to this one. The tasks were: Use a loop to minimize repeated code. Use an if statement to print out check digits of 10 as X.

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total = 0; total needs to be initialized before loop

Sample Solution Code

import javax.swing.*;
import java.util.Date;

/**
 *
 * This program will read in the first 9 digits of an ISBN and print out the 9 digits
 * along with the valid 10th check digit. This code uses a loop structure to remove redundant code
 * Note that this code will handle the possibility of the check digit being an 'X'.
 *
 * @author:     1010 Instructors
 * @version:    2007-September
 *
 */

public class CaseStudy2_ISBN_Solution  
{

    public static void main (String [] args) 
    {

        //variables declared here
        String temp;        //temporary input string
	int isbn;           //9-digit ISBN
	int digit;          //isolated ISBN digit
        int total = 0;      //total of isbn number when each digit is multiplied by check value
	int checkDigit;     //value of total%11(as per ISBN standard)

        //get input
	temp= JOptionPane.showInputDialog ("Enter first 9 digits of ISBN");
	isbn = Integer.parseInt (temp);

        System.out.println ("You have entered " + temp + ".\n\nThe weighted value of the ISBN is:");

	for (int i=9; i>0; i--) 
        {
            digit = isbn % 10;
	    isbn = isbn / 10;
	    total = total + digit * i;
	    System.out.println (digit + " * " + 9 + " for a running total of " + total);
	}
	
        //calculate check digit
        checkDigit = total % 11;

        System.out.println ("The weighted total is: " + total);

        //if check digit is equal to 10 then print an 'X', otherwise print the checkDigit value
	if (total%11 == 10) 
        {
	    System.out.println ("The check digit is: 'X'");
	    System.out.println ("\nThe 10-digit ISBN is: " + temp + 'X');
	}
	else 
        {
	    System.out.println ("The check digit is: " + total%11);
	    System.out.println ("\nThe 10-digit ISBN is: " + temp + checkDigit);
	}

	System.out.println ("\nProgrammed by COMP 1010 Instructors");
	System.out.println ("Date: " + new Date());
	System.out.println ("*** End of Processing ***");

    }//end main
}//end class

Links To Case Studies

Case Study I: Day One at Funky Books Inc.
Case Study II: Day Two at Funky Books Inc.
Case Study III: Day Three at Funky Books Inc.

Case Study IV: Day Four at Funky Books Inc.