Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

a little bug

Posted on 2008-06-17
5
Medium Priority
?
214 Views
Last Modified: 2010-03-30
hi,
 I have  a small problem in java, but not in c or c++. I guess the type problem . However, I don't know how to fix. please help.

if the input is 10.19 & 10.31, the result is supposed to be 12. However, I have Pennies are 12.000084.

if i change the line pennies = (amountReceived - amountDue) *100;
to pennies = amountReceived*100 - amountDue *100;

I will get correct answer because values are converted to int before do calculation. I just wonder what if I do some division program. How cold I avoid this problem? Thanks

import java.util.*;
import java.io.*;
class Demo
{
	public static void main ( String[] args)
	{
		Scanner temp;
		float amountDue, amountReceived;
 
		System.out.print("Enter the amountDue : " );
		temp = new Scanner( System.in);
        amountDue      = temp.nextFloat();
 
		System.out.print("Enter the amountReceived :");
		temp = new Scanner( System.in);
		amountReceived = temp.nextFloat();
 
		float pennies, nickels, dimes, quarters, dollars;
		float container;
 
		pennies = (amountReceived - amountDue) *100;
		System.out.print("Pennies are " + pennies + "\n");
 
	}
}

Open in new window

0
Comment
Question by:valleytech
  • 2
  • 2
5 Comments
 
LVL 11

Assisted Solution

by:spoxox
spoxox earned 1200 total points
ID: 21809212
Floating point numbers' representation at the machine's level are not exact, so errors like this happen.

A Formatter or System.out.format can help.

See http://java.sun.com/j2se/1.5.0/docs/api/java/util/Formatter.html
0
 
LVL 11

Accepted Solution

by:
spoxox earned 1200 total points
ID: 21809217

                System.out.format("Pennies are %4.2f", pennies);
0
 
LVL 6

Assisted Solution

by:psychic_zero
psychic_zero earned 800 total points
ID: 21809261
Maybe this is due to you're using float type. Maybe you can use number formatting to make sure the result is 12 by adding this code:

pennies = (amountReceived - amountDue) *100;
 
NumberFormat formatter = new DecimalFormat("##"); 
String s = formatter.format(pennies);
 
System.out.print("Pennies are " + pennies + "\n");

Open in new window

0
 
LVL 6

Expert Comment

by:psychic_zero
ID: 21809265
To do my way, I think you need to include import java.text.*;
0
 

Author Comment

by:valleytech
ID: 21809403
and pennies must be s


for future reference

import java.text.*;

pennies = (amountReceived - amountDue) *100;
 
NumberFormat formatter = new DecimalFormat("##");
String s = formatter.format(pennies);
 
System.out.print("Pennies are " + pennies + "\n");
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction Java can be integrated with native programs using an interface called JNI(Java Native Interface). Native programs are programs which can directly run on the processor. JNI is simply a naming and calling convention so that the JVM (Java…
Java Flight Recorder and Java Mission Control together create a complete tool chain to continuously collect low level and detailed runtime information enabling after-the-fact incident analysis. Java Flight Recorder is a profiling and event collectio…
Viewers learn how to read error messages and identify possible mistakes that could cause hours of frustration. Coding is as much about debugging your code as it is about writing it. Define Error Message: Line Numbers: Type of Error: Break Down…
This tutorial explains how to use the VisualVM tool for the Java platform application. This video goes into detail on the Threads, Sampler, and Profiler tabs.
Suggested Courses

916 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question