asked on

how to subtract decimal????

hi guys!!!!

i had a program that subtract two double variable.here's my code:

import java.awt.*;
import java.awt.event.*;

public class Try
{

public static void main(String argv[])
{
Frame fr = new Frame();
fr.pack();
fr.setVisible(true);

Panel panel = new Panel();

final TextField tf1 = new TextField(15);
final TextField tf2 = new TextField(15);

final Button subtract = new Button("Minus");
Button clear = new Button("Clear");
subtract.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == subtract)
{
double a = new Double(tf1.getText()).doubleValue();
double b = new Double(tf2.getText()).doubleValue();

System.out.println(a-b);
}
}

});

panel.add(tf1);
panel.add(tf2);
panel.add(subtract);
panel.add(clear);

fr.add(panel);
}//End of main

}

OUTPUT:

TF1 = 50.56
TF2 = 25
DIFFERENCE = 25.560000000000002

how would i make it so that it will only return 25.26???

thanks in advance!!!

Mick Barry

That's simply a rounding error resulting from floating point arithmetic. If you need to avoid this then use the BigDecimal class, or simply format your output to two decimal places.

rdy1437

ASKER

can you provide sample code for this??

Mick Barry

BigDecimal a = new BigDecimal("50.56");
BigDecimal b = new BigDecimal("25");
BigDecimal c = a.subtract(b);
System.out.println(c);

Mick Barry

Floating point numbers are only an approximation (albeit quite an accurate one).

girionis

There is also an excellent tutorial on BigDecimal: http://www.javaworld.com/javaworld/jw-06-2001/jw-0601-cents.html

vogen gurung

// rdy1437, here is the solution:

import java.awt.*;
import java.awt.event.*;
import java.text.DecimalFormat;

public class Try
{
public static void main(String argv[])
{
Frame fr = new Frame();
fr.pack();
fr.setVisible(true);
Panel panel = new Panel();

final TextField tf1 = new TextField(15);
final TextField tf2 = new TextField(15);

final Button subtract = new Button("Minus");
Button clear = new Button("Clear");
subtract.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
DecimalFormat twoDigits = new DecimalFormat( "0.00" );
if (e.getSource() == subtract)
{
double a = new Double(tf1.getText()).doubleValue();
double b = new Double(tf2.getText()).doubleValue();
double result =(double) a - (double) b;
System.out.println( twoDigits.format(result) );
}
}
});
panel.add(tf1);
panel.add(tf2);
panel.add(subtract);
panel.add(clear);
fr.add(panel);
}//End of main
}

vogen gurung

DecimalFormat object that is initialized with the string "0.00". Each 0 is a format flag that specifies a required digit position in the formatted floating-point number.

pls ask if have any question..

cheers

Mick Barry

vogen,

1. Please avoid proposing answers as it locks the question and make it harder for other experts to contribute.

2. I had already suggested the option of using formatting.

rdy1437

ASKER

thanks guys for your comments.i already used the comment made by objects...

Mick Barry

Good to hear it helped :-)
Can you accept my comment as an answer then please.

vogen gurung

solly, i was only trying to help.. ::(

rdy1437

ASKER

hey objects how can i give you the points?

ASKER CERTIFIED SOLUTION

Mick Barry