@Max/@Min with double

emmanuel · **Posted:** Wed Mar 04, 2009 8:23 pm

We have been discussing the possibility of allowing @Min and @Max to get double values instead of the current long.
There are various problems with that though.

http://firstclassthoughts.co.uk/java/tr ... traps.html
explains a lot of traps around double

Quote:

To evaluate @Min @Max we do comparison so

say @Max(2.3d) applied on 2.2999999999999997d

System.out.println(2.2999999999999997d < 2.3d); => displays false
System.out.println(new BigDecimal(""+2.2999999999999997d).compareTo(
new BigDecimal(""+2.3d) ) == -1); => displays false
System.out.println( new BigDecimal(9223372036854775807l).compareTo(new
BigDecimal(9223372036854775807d)) == 0 ); => displays false

not a pleasant surprise

To which Sebastian replies

Quote:

You have the same problem when the max value is a long:

System.out.println(0.99999999999999997d < 1L);

So one part is the question do we support the @Max for float and double
properties? And if so how do we address this issue?

So

1. do we support float and double for @Min / @Max?
2. if 1 is yes, I'd be inclined to say the value should be double but that's not fully automatic.

Thoughts?

max · **Posted:** Wed Mar 04, 2009 8:39 pm

the only way that will work is to use string and pass it to BigDecimal.

Fabio Kung · **Joined:** Wed Mar 04, 2009 10:42 pm **Posts:** 1

Or you could rely on some configurable delta

jasonbayk · **Joined:** Tue Nov 21, 2006 6:46 pm **Posts:** 6

I hate to say this, but
1. double validation is absolute must (otherwise ability to model real world using JSR 303 will be severely limited)
2. @tolerance (optional, with default as 0.0d) annotation have to be introduced to let #1 work in most of the cases