Math.round( -.5)?

[Tom Adams]

Does it seem odd that java rounds -.5 to zero?
Is that right?

package com.test;
public class RoundTest2 {
public static void main(String[] args) {
double[] a = {-.5d,-1.5,-2.5,1.5,1.75};
for (int i=0; i < a.length; i++ ) {
System.out.println( "Math.round( " + a[i] + " ) = " + Math.round(a[i]) );
}
}
}
---------- run ----------
Math.round( -0.5 ) = 0
Math.round( -1.5 ) = -1
Math.round( -2.5 ) = -2
Math.round( 1.5 ) = 2
Math.round( 1.75 ) = 2
Output completed (0 sec consumed) - Normal Termination

[Jessica Sant]

check out the API for Math.round(double)
Returns the closest long to the argument. The result is rounded to an integer by adding 1/2, taking the floor of the result, and casting the result to type long. In other words, the result is equal to the value of the expression:
(long)Math.floor(a + 0.5d)
So... it behaves just like it's supposed to.

[Tom Adams]

Yea...I read that also. Is it just me or does this seem strange? Just as a check excel and MS SQL Server both feel that -.5 should be rounded to -1. :roll:

[Jessica Sant]

lol yes -- it does seem a little strange... maybe you can write your own method called
long roundTheWayIExpectItToBehave(double d)
and use that??