Re: Finding nearest location, calculating distance - best way to store and sort info?

Matt Kime wrote:
> I have a database of addresses and i'm trying to find the nearest
> locations. Rather than computing the distance for all the addresses in
> the database, I'm starting by creating an array of addresses within x
> distance. Now that I have my array, I'm finding myself at my limit of
> java knowledge. I'd like to create an associative array that i can
> sort with, storing objects and sorting on their distance. What is the
> best java tool for this? The different types of maps are confusing me
> and I'm not sure if they'll work for what i want anyway. (it seems
> that a sortedMap won't work if I want to store an object - no way to
> compare my address objects)
>
> what solutions have you employed?

When I've had to do this I used the database to calculate and return the 
addresses in sorted order using a city-block metric.

Say you have the addresses with lat/long info.  You want the addresses 
within 5 miles of a given address.  The SQL (yeah, I know, evil) would 
be something like

    SELECT address from ADDRESS where address.x between ($1.x and $1.x + 
5) and address.y between ($1.y and $1.y + 5).

If you want to do it in Java then you can put everything into an array 
and write a custom Comparator to do the calculation for you:
    Collections.sort(array, new Comparator() { ...distance calculation });

Are these enough of hints?
-arturo