Fix for 5015163, and my first webrev (original) (raw)
Kevin Bourrillion kevinb at google.com
Fri Feb 6 23:03:04 UTC 2009
- Previous message: Fix for 5015163, and my first webrev
- Next message: Fix for 5015163, and my first webrev
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Hello,
A few thoughts.
First, this functionality is badly needed. Absolutely everyone rewrites this, in hundreds of different ways. At Google we're no exception, we have our own hand-rolled Join.java class full of static methods, and it has thousands of callers in our private codebase.
Your selection of overloads (Iterable, Object[], and (Object,Object...)) is exactly correct. Kudos. We'd added Iterator versions as well, but almost no one uses them, so forget that.
My main concerns with your current API are:
I don't think that ",".join(collection) is a good idea. It clashes too strongly with the StringBuilder etc. versions. It also plain "looks weird". A static String.join(",", collection) is preferable. I don't think anyone would be surprised by this.
It should be considered separately whether to support other Appendables via static methods (somewhere) like:
Iterable<?> tokens) throws IOException
This provides a superset of what your StringBuilder etc. methods can do, but your methods are still good because of their convenience especially in chains of method calls, and because they don't need to throw any exception.
The biggest problem we've had with our Join class is that it turns out that everyone has a different idea of how they'd like nulls handled.
- output as "null" (your, and our, current behavior)
- skip?
- skip only if trailing?
- throw NPE? (often the best thing)
We now support everyone by having the concept of an instantiable Joiner (I've seen this in other languages). Example:
private static final Joiner JOINER = Joiner.with(", ").skipNulls();
. . .
return JOINER.join("Harry", "Ron", "Hermione");Just to give everyone food for thought, our Joiner's API currently looks like this:
static Joiner with(String separator)
Joiner skipNulls() Joiner useForNull(String nullText)
A appendTo(A appendable, Iterable<?> parts) throws IOException A appendTo(A appendable, Object[] parts) throws IOException A appendTo(A appendable, Object first, Object... rest) throws IOException
StringBuilder appendTo(StringBuilder builder, Iterable<?> parts) StringBuilder appendTo(StringBuilder builder, Object[] parts) StringBuilder appendTo(StringBuilder builder, Object first, Object... rest)
String join(Iterable<?> parts) String join(Object[] parts) String join(Object first, Object... rest)
MapJoiner withKeyValueSeparator(String keyValueSeparator)
class MapJoiner { A appendTo(A appendable, Map map) throws IOException StringBuilder appendTo(StringBuilder builder, Map map) String join(Map map)
MapJoiner useForNull(String nullText)}
End of random thoughts.
On Fri, Feb 6, 2009 at 12:59 PM, Rémi Forax <forax at univ-mlv.fr> wrote:
Hi all, bug 5015163 is a RFE that advocate to add a method join (like in Python) to String/StringBuilder/StringBuffer. Here is the corresponding webrev (using the new infrastucture :) http://cr.openjdk.java.net/~forax/5015163/webrev.00/ The patch is against tl repository. Who want to review it ? For the record, i have previously proposed this fix using the jdk-collaboration forum more than one year ago but because i am lazy i haven't take the time to post it here. cheers, Rémi Forax
-- Kevin Bourrillion @ Google internal: http://go/javalibraries google-collections.googlecode.com google-guice.googlecode.com
- Previous message: Fix for 5015163, and my first webrev
- Next message: Fix for 5015163, and my first webrev
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]