truncating java doubles

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Jeremy Watts - 23 Oct 2007 19:10 GMT

Hi,

How do you truncate java doubles? I am trying to convert a double to a
number thats rounded to 3 decimal places - i can do this using BigDecimals
easily but cant seem to find anything to do the same with a double.

Thanks

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Manish Pandit - 23 Oct 2007 19:28 GMT

> Hi,
>
[quoted text clipped - 3 lines]
>
> Thanks

NumberFormat might be the solution what you're looking for (http://
java.sun.com/j2se/1.4.2/docs/api/java/text/NumberFormat.html).

-cheers,
Manish

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Roedy Green - 23 Oct 2007 20:32 GMT

On Tue, 23 Oct 2007 18:10:54 GMT, "Jeremy Watts"
<jwatts1970@hotmail.com> wrote, quoted or indirectly quoted someone
who said :

>How do you truncate java doubles? I am trying to convert a double to a
>number thats rounded to 3 decimal places - i can do this using BigDecimals
>easily but cant seem to find anything to do the same with a double.

see http://mindprod.com/jgloss/round.html

Signature

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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sengsational - 23 Oct 2007 20:37 GMT

> Hi,
>
[quoted text clipped - 3 lines]
>
> Thanks

     double d = Math.PI * 20000;
     NumberFormat f = NumberFormat.getInstance();
     f.setMinimumFractionDigits(3);
     System.out.println("d:" + d);
     System.out.println("a:" + f.format(d));
     System.out.println("b:" + ((int)(d * 1000))/ 1000d);

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www - 24 Oct 2007 14:26 GMT

>     double d = Math.PI * 20000;
>     NumberFormat f = NumberFormat.getInstance();
>     f.setMinimumFractionDigits(3);
>     System.out.println("d:" + d);
>     System.out.println("a:" + f.format(d));
>     System.out.println("b:" + ((int)(d * 1000))/ 1000d);

You will see more difference(due to rounding) between a: and b:

    double d = Math.PI * 20000 + 0.0006;
    NumberFormat f = NumberFormat.getInstance();
    f.setMinimumFractionDigits(3);
    System.out.println("d:" + d);
    System.out.println("a:" + f.format(d));
    System.out.println("b:" + ((int)(d * 1000))/ 1000d);

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truncating java doubles

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