Re: Sorting based on multiple parameters

From:

Patricia Shanahan <pats@acm.org>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 14 Nov 2007 06:48:18 -0800

Message-ID:

<13jm2lioqvvq1ba@corp.supernews.com>

Manish Hatwalne wrote:

I am little brain-dead today. Having problems writing comparator that will
do comparison (for sorting) for multiple parameters.

Here is what I need to do - I have object MyObj with several fields. now I
need to sort a collection of such objects based on list of fields supplied.
So say if I want to sort MyObj collection based on fields "date" & "price" -
similar to SQL "...order by date, price" - how do I do this?

Or in other words, how do I write comparator for following method?

[code]
List sort(Collection<MyObj> objects, final List sortFields, final
List<Enum.ASC/DESC> ascDesc){

}
[/code]

any pointers, help would be highly appreciated!

Create an ArrayList<MyObj> using the Collection objects as the
constructor parameter. Apply Collections.sort to the List<MyObj> with a
Comparator to do the sorting.

That reduces the problem to writing a Comparator<MyObj> that orders
based on a list of fields. Do you have a plan yet for specifying the
list of fields? Are they all Comparable?

Patricia