Name: nt126004 Date: 01/02/2002


FULL PRODUCT VERSION :
java version "1.4.0-beta3"
Java(TM) 2 Runtime Environment, Standard Edition (build
1.4.0-beta3-b84)
Java HotSpot(TM) Client VM (build 1.4.0-beta3-b84, mixed mode)



FULL OPERATING SYSTEM VERSION :
Microsoft Windows 2000 [Version 5.00.2195] SP2



A DESCRIPTION OF THE PROBLEM :
In the javadoc for java.util.regex.Matcher.appendReplacement
http://java.sun.com/j2se/1.4/docs/api/java/util/regex/Matcher.html#appendReplacement(java.lang.StringBuffer,%20java.lang.String)

the explanation does not describe how g is delimited in $g.

For example, I found that $99 was parsed as $9, so I thought
that g was limited to a single digit. Later I happened to
look at the code, and this appears to be incorrect: numerals
are added only if the result does not exceed the number of
groups in the pattern.

1. This non-obvious behavior should at least be documented.

2. I suggest there should be flag which causes the matcher
to throw an exception instead when the numeral exceeds the
groupCount. setGroupCountLimitsParse(boolean) or something.

3. There should be an (alternate) syntax which provides an
explicit delimiter. A problematic situation arises when the
following characters in the template are digits. For
example, suppose that $1 is bound to the hour, say 12, and I
want to produce military time of 1200hours. Writing
$100hours won't work if there are at least 10 groups, since
it will be parsed as $10 rather than as $1. (If there is
another workaround for this case that I don't see, it needs
to be explained.)

This bug can be reproduced always.
(Review ID: 137481)
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