On 2/4/2013 10:13 AM, Stephen Colebourne wrote:
On 4 February 2013 18:09, Brian Burkhalter <brian.burkhal...@oracle.com> wrote:
While stripTrailingZeros() should perhaps for purity of specification always
return BigDecimal.ZERO for anything which is numerically equal to zero, the
present behavior of this method has been extant for some years, so following
the prevailing convention it would be preferable to modify the specification to
match the behavior.
Proposed change:
diff -r 20eeb727d171 -r 8789e8736763 src/share/classes/java/math/BigDecimal.java
--- a/src/share/classes/java/math/BigDecimal.java Fri Feb 01 16:32:53
2013 -0800
+++ b/src/share/classes/java/math/BigDecimal.java Fri Feb 01 16:32:53
2013 -0800
@@ -2589,7 +2589,9 @@
* the {@code BigDecimal} value {@code 600.0}, which has
* [{@code BigInteger}, {@code scale}] components equals to
* [6000, 1], yields {@code 6E2} with [{@code BigInteger},
- * {@code scale}] components equals to [6, -2]
+ * {@code scale}] components equals to [6, -2]. This method has no
+ * effect on a {@code BigDecimal} <i>x</i> which is numerically
+ * equal to zero, i.e., {@code x.compareTo(BigDecimal.ZERO) == 0}.
*
* @return a numerically equal {@code BigDecimal} with any
* trailing zeros removed.
This is a bug that has bitten me on more than one occasion. Changing
the spec is not the solution here. Fixing the bug is.
Stephen
The stripTrailingZeros method has acted in this surprising way since the
IBM-led JSR 13 was integrated into the platform back in JDK 5, which
shipped in 2004.
This situation is analogous to when the specification and behavior
disagree. Our general policy to resolve such cases when evolving the
JDK is:
"..., there are times in evolving the JDK when differences are found
between the specified behavior and the actual behavior (for example
4707389, 6365176). The two basic approaches to fixing these bugs are to
change the implementation to match the specified behavior or to change
the specification (in a platform release) to match the implementation's
(perhaps long-standing) behavior; often the latter option is chosen
since it has a lower de facto impact on behavioral compatibility."
http://cr.openjdk.java.net/~darcy/OpenJdkDevGuide/OpenJdkDevelopersGuide.v0.777.html
If this issue were being addressed before JDK 5 shipped or even during
JDK 6, I would support changing the behavior of stripTrailingZeros.
However, for addressing this in JDK 8, I think it is more appropriate to
keep the behavior as-is and document this special case.
-Joe
