validation of code

**sukatoa** · Mar 26 '08, 04:26 AM

Originally posted by soty

HI

i wrote a code to validate cash for a vending machine.... the problem am having is dat dat my code failed to validate any ammount.

please help!!!!

the code is below

public static double validDollarNote () {

boolean done = false;
double cash = 0.0;
String bill;

double Nickel = 0.05;
double Dime = 0.10;
double Quarter = 0.25;
double OneDollar = 1.0;
double FiveDollar = 5.0;

while (!done) {

bill = JOptionPane.sho wInputDialog("P ay:");

try {
cash = Double.parseDou ble(bill);
System.out.prin tln(cash);

if (cash != Dime || cash != Nickel || cash != Quarter || cash != OneDollar || cash != FiveDollar) {
throw new NumberFormatExc eption();
}
else
{
done = true;
}
} catch (NumberFormatEx ception e) {
JOptionPane.sho wMessageDialog( null, "MACHINE ACCEPTS: $.05,$.10,$.25, $1,$5\n",
"Error", JOptionPane.INF ORMATION_MESSAG E);

}
}

return cash;

}

Hello soty, i've test your code... There is something strange about your if statement....

Assume true = 1 and false = 0....

If you convert your if statement into logic...

OR = ||
AND = &&

@ OR, if one of the equality test is true, then it should return true/1
@ AND, if at least one of the equality test is false, it should return false/0

OR represents in logic as + (addition)
AND represents in logic as * (multiply)

the if statement encounters 1/true inside of ( here ), then it will allow to execute the statements inside of it....

@ your if statement,

if ( (cash != Dime || cash != Nickel || cash != Quarter || cash != OneDollar || cash != FiveDollar)

if i will enter a value .05

it is equivalent to

if ( 0 + 1 + 0 + 0 + 0) and the total is 1...

obviously it will execute all the statements inside of it....

try this one,

Code:

if((cash==Dime)||(cash==Nickel)||(cash==Quarter)||(cash==OneDollar)||(cash==FiveDollar)) {
	done = true;
} 
else {
	throw new NumberFormatException();
}

Have some experiments on it.

update us,
sukatoa

**sukatoa** · Mar 26 '08, 04:41 AM

Dont forget to inclose your code with codetags.... ;-)

just reminding
sukatoa...

**JosAH** · Mar 26 '08, 07:08 AM

Originally posted by soty

double Nickel = 0.05;
double Dime = 0.10;
double Quarter = 0.25;
double OneDollar = 1.0;
double FiveDollar = 5.0;

Don't do that. The IEEE floating point number system can't represent values
such as 0.1 exactly. Only numbers that are a sum of negative powers of two
times an exponent value can be represented exactly.

e.g. try to make 1/10 given the numbers 1/2, 1/4, 1/8, 1/16, 1/32 ... etc by
using each number at most once. For a thorough explanation read this.

Use the following monetary units instead:

[code=java]
int Nickel = 5;
int Dime = 10;
int Quarter = 25;
int OneDollar = 100;
int FiveDollar = 500;
[/code]

i.e. the monetary unit is the penny/cent instead of the dollar.

kind regards,

Jos

**soty** · Mar 28 '08, 04:59 PM

hi

av finished the code but i'm having one slight problem.....eit her av lost it or i'm jus not thinking straight.... either way i guess my logic is not coming out well.

the problem am having wif this code is that each time i wanna calculate my total sales its resets it to present price. it doesn't add it up.... please can u look into it?

thanks

Code:


/*
 *  Name :Uju
 *  Project: Vending Machine 
 *  Program: This Program uses JOptionPane to assimulate a vending machine          
 *  that can allow ther user select more that one item at each time and displays  
 *  the total expenses in that transaction
 */

import javax.swing.JOptionPane;
import javax.swing.*;
import java.util.Date;
import java.text.DecimalFormat;

public class vending {

    public static void main(String[] args) {

        vencalc();


    }

    public static int getoption() {     // this method get the displays the menue 
        //and validates the range for the option

        int option = 0;
        String choice;
        boolean done = false;

        Date currentdate = new Date();

        while (!done) {
            choice = JOptionPane.showInputDialog(null, "UJU'S VENDING MACHINE\n" + currentdate + "\n\n" + "SELECT YOUR CHOICE\n\n1     CHIPS\n2     MINT GUM\n3     NACHOS\n4     COOKIES" +
                    "\n5     LIFESAVER\n6     M&M\n7     WALNUT\n8     POPCORN\n9     MIXED NUT\n");

            if (choice == null) {
                finish();
            }

            try {

                option = Integer.parseInt(choice);
                if (option < 1 || option > 9) {
                    throw new NumberFormatException();
                } else {
                    done = true;
                }

            } catch (NumberFormatException e) {
                JOptionPane.showMessageDialog(null, "your entery was not in proper format.",
                        "Error", JOptionPane.INFORMATION_MESSAGE);
            }
        }
        return option;

    }

    public static void vencalc() {// this method calculates the vend machine.
        int val = 0;
        double price = 0.0;
        int outOfStock = 0;
        int chipInStock = 2;
        int mintgumInStock = 5;
        int nachoInStock = 5;
        int cookiesInStock = 5;
        int lifesaverInStock = 5;
        int mandmInStock = 5;
        int walnutInStock = 5;
        int popcornInStock = 5;
        int mixednutInStock = 5;
        double total = 0;

        boolean instock = true;

        while (true) {
            val = getoption();

            switch (val) {
                case 1:
                    price = 1.85;
                    instock = (chipInStock > 0);
                    break;
                case 2:
                    price = 0.95;
                    instock = (mintgumInStock > 0);
                    break;
                case 3:
                    price = 1.00;
                    instock = (nachoInStock > 0);
                    break;
                case 4:
                    price = 2.15;
                    instock = (cookiesInStock > 0);
                    break;
                case 5:
                    price = 1.05;
                    instock = (lifesaverInStock > 0);
                    break;
                case 6:
                    price = 0.85;
                    instock = (mandmInStock > 0);
                    break;
                case 7:
                    price = 4.20;
                    instock = (walnutInStock > 0);
                    break;
                case 8:
                    price = 1.15;
                    instock = (popcornInStock > 0);
                    break;
                case 9:
                    price = 1.15;
                    instock = (mixednutInStock > 0);
                    break;
            }


            Continue(price, instock,total);// this calls the continue method
            switch (val) {
                case 1:
                    chipInStock -= 1;
                    break;
                case 2:
                    mintgumInStock -= 1;
                    break;
                case 3:
                    nachoInStock -= 1;
                    break;
                case 4:
                    cookiesInStock -= 1;
                    break;
                case 5:
                    lifesaverInStock -= 1;
                    break;
                case 6:
                    mandmInStock -= 1;
                    break;
                case 7:
                    walnutInStock -= 1;
                    break;
                case 8:
                    popcornInStock -= 1;
                    break;
                case 9:
                    mixednutInStock -= 1;
                    break;
            }

            if (instock == false) {
                outOfStock = JOptionPane.showConfirmDialog(null, "Sorry, out of this item" +
                        "\nWould you like to choose another item?", "Question", JOptionPane.YES_NO_OPTION);
            }
            if (outOfStock == 1) {
                JOptionPane.showMessageDialog(null, "Please pick up your money and" +
                        "come back soon", "\nGOOD BYE!!!", JOptionPane.INFORMATION_MESSAGE);
                finish();
            }
        }


    }

    public static int getAnswer(double price) {// method that confirms if 
        //the customer wants to purshace the item

        int ans;

        ans = JOptionPane.showConfirmDialog(null, "Do you want to purchase this item?" +
                "\nItem Price: $" + price, "Confirmation", JOptionPane.YES_NO_OPTION);

        return ans;
    }

    public static void Continue(double price, boolean instock,double total) {// this method confirms for 
        //the second time if the user wants to exit
        int ans;

        ans = getAnswer(price);
        if (ans == 0) {
            collect(price, instock,total);
        } else if (ans == 1) {
            ans = JOptionPane.showConfirmDialog(null, "Do you want to purchase " +
                    "another item?", "Question", JOptionPane.YES_NO_OPTION);
            if (ans == 1) {
                finish();
            }
        }

    }

    public static double validDollarNote(double price) {// this method validates the cash input

        boolean done = false;
        double cash = 0.0;
        String bill;

        double Nickel = 0.05;
        double Dime = 0.10;
        double Quarter = 0.25;
        double OneDollar = 1.0;
        double FiveDollar = 5.0;


        while (!done) {

            bill = JOptionPane.showInputDialog("Pay:" + price);

            try {
                cash = Double.parseDouble(bill);
                System.out.println(cash);

                if (cash == Dime || cash == Nickel || cash == Quarter || cash == OneDollar || cash == FiveDollar) {
                    done = true;
                } else {
                    throw new NumberFormatException();
                }
            } catch (NumberFormatException e) {
                JOptionPane.showMessageDialog(null, "MACHINE ACCEPTS: $.05,$.10,$.25,$1,$5\n",
                        "Error", JOptionPane.INFORMATION_MESSAGE);

            }
        }

        return cash;

    }

    public static void finish() {// this is an exit method
        System.exit(0);
    }

    public static void collect(double price, boolean instock,double total) {// this this method calculates and 
        //and validates cash input.
        boolean done = false;
        double Nickel = 0.05;
        double Dime = 0.10;
        double Quarter = 0.25;
        double OneDollar = 1.0;
        double FiveDollar = 5.0;
        double amtToPay;
        String cash = null;
        double money;
        int reply;


        DecimalFormat twoDigits = new DecimalFormat("$0.00");

        amtToPay = validDollarNote(price);
        
        total+= price;
        

        while (amtToPay < price) {

            while (!done) {

                cash = JOptionPane.showInputDialog(null, "Not enough Cash for the purshase\n\n" +
                        "Please pay " + twoDigits.format(price - amtToPay) + " to complete your transaction");

                try {
                    money = Double.parseDouble(cash);

                    System.out.println(cash);

                    if (money == Dime || money == Nickel || money == Quarter || money == OneDollar || money == FiveDollar) {
                        done = true;
                    } else {
                        throw new NumberFormatException();
                    }
                } catch (NumberFormatException e) {
                    JOptionPane.showMessageDialog(null, "MACHINE ACCEPTS: $.05,$.10,$.25,$1,$5\n",
                            "Error", JOptionPane.INFORMATION_MESSAGE);

                }
            }

            if (cash == null) 
            {
                vencalc();;
            } 
            else 
            {
                amtToPay += Double.parseDouble(cash);
            }

        }

        if (amtToPay == price && instock) {
            
            reply =JOptionPane.showConfirmDialog(null, "Do you want to purchase " +
                    "another item?", "Question", JOptionPane.YES_NO_OPTION);
           
             if (reply == 1){
                JOptionPane.showMessageDialog(null, "please pick up you item\n" + "\nTOTAL: " 
                        + twoDigits.format(total) + "\nThank you");
            finish();}
        }
            
          else if (amtToPay > price && instock) {

            reply =JOptionPane.showConfirmDialog(null, "Do you want to purchase " +
                    "another item?", "Question", JOptionPane.YES_NO_OPTION);
            if (reply == 1){
                JOptionPane.showMessageDialog(null, "please pick up you item\n" + "\nTOTAL: "
                        + twoDigits.format(total) + "\nThank you");
            finish();}
            }

        }
}

validation of code

validation of code

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