ArrayList Search for Value

[John Veldthuis]

I have an ArrayList set up with a set of class objects.

The class has 3 strings in it and are as follows

ProdID
GSP
Description

Okay now problem with getting all these into the list and displaying them correctly and manipulating
things except for one thing.

I wish to be able to do search through the whole list without stepping through the entire list
enumerating them. I would just like to be able to search on one field. The ProdID.

For now I do it by

dim myspec as new clsSpecs
for each myspec in specList
if test.prodid.com pareto(myspec.P rodID) = 0 then

do stuff

end if

next


Now this works but I am looking for a search method but list.BinarySear ch does not seem to do it.

Any help?

[Peter van der Goes]

Re: ArrayList Search for Value


"John Veldthuis" <johnv@no.spamo .paradise.net.n z> wrote in message
news:man0l1lvf1 5433qpv1fiqkaad k1tei5ud7@4ax.c om...[color=blue]
>I have an ArrayList set up with a set of class objects.
>
> The class has 3 strings in it and are as follows
>
> ProdID
> GSP
> Description
>
> Okay now problem with getting all these into the list and displaying them
> correctly and manipulating
> things except for one thing.
>
> I wish to be able to do search through the whole list without stepping
> through the entire list
> enumerating them. I would just like to be able to search on one field. The
> ProdID.
>
> For now I do it by
>
> dim myspec as new clsSpecs
> for each myspec in specList
> if test.prodid.com pareto(myspec.P rodID) = 0 then
>
> do stuff
>
> end if
>
> next
>
>
> Now this works but I am looking for a search method but list.BinarySear ch
> does not seem to do it.
>
> Any help?[/color]

I suggest you read this article:

http://msdn.microsoft.com/library/de...archtopic1.asp

You'll note that the objects in your ArrayList must come from a class that
implements the IComparable interface, and that the objects must be sorted
according to your IComparable implementation. Then the BinarySearch method
will yield the results you seek.

--
Peter [MVP Visual Developer]
Jack of all trades, master of none.

[John Veldthuis]

Re: ArrayList Search for Value

On Fri, 14 Oct 2005 22:57:42 -0500, "Peter van der Goes" <p_vandergoes@t oadstool.u> wrote:

Thanks. I had implemented IComparable to sort the list but was using it on the GSP entry.
I changed it to look at the ProdID and it did return what I expected. Changed it back as that was
what I needed the main sort on.

However I added an IComparable called FindProdID and used the following

myspec = new clsSpecs
mySpec.ProdID = "100676"
indx = specList.Binary Search(myspec, new FindProdID)

and all worked well and returned the index it should have.

Thanks for the pointer.
[color=blue]
>
>"John Veldthuis" <johnv@no.spamo .paradise.net.n z> wrote in message
>news:man0l1lvf 15433qpv1fiqkaa dk1tei5ud7@4ax. com...[color=green]
>>I have an ArrayList set up with a set of class objects.
>>
>> The class has 3 strings in it and are as follows
>>
>> ProdID
>> GSP
>> Description
>>
>> Okay now problem with getting all these into the list and displaying them
>> correctly and manipulating
>> things except for one thing.
>>
>> I wish to be able to do search through the whole list without stepping
>> through the entire list
>> enumerating them. I would just like to be able to search on one field. The
>> ProdID.
>>
>> For now I do it by
>>
>> dim myspec as new clsSpecs
>> for each myspec in specList
>> if test.prodid.com pareto(myspec.P rodID) = 0 then
>>
>> do stuff
>>
>> end if
>>
>> next
>>
>>
>> Now this works but I am looking for a search method but list.BinarySear ch
>> does not seem to do it.
>>
>> Any help?[/color]
>
>I suggest you read this article:
>
>http://msdn.microsoft.com/library/de...archtopic1.asp
>
>You'll note that the objects in your ArrayList must come from a class that
>implements the IComparable interface, and that the objects must be sorted
>according to your IComparable implementation. Then the BinarySearch method
>will yield the results you seek.[/color]

[Cor Ligthert [MVP]]

Re: ArrayList Search for Value

John,

If you are sure that you want to use the complete word in the exact cases,
than you can use the arraylist indexof method

http://msdn.microsoft.com/library/de...dexoftopic.asp

If you want it undependable from the cases than you should be able to use
the Icomparer as nicely described by Peter Proost, Jay B. Harlow and more
people in this newsgroup this week

http://groups.google.com/group/microsoft.public.dotnet.languages.vb/browse_frm/thread/7c81c7c859a13cd0/639adf0d52e87dfc#639adf0d52e87dfc

If you are the same John, than forget this message.

I hope this helps,

Cor

[Dennis]

Re: ArrayList Search for Value

Don't you have to sort the arraylist on the ProdID property first before
using the binarysearch?
--
Dennis in Houston


"John Veldthuis" wrote:
[color=blue]
> On Fri, 14 Oct 2005 22:57:42 -0500, "Peter van der Goes" <p_vandergoes@t oadstool.u> wrote:
>
> Thanks. I had implemented IComparable to sort the list but was using it on the GSP entry.
> I changed it to look at the ProdID and it did return what I expected. Changed it back as that was
> what I needed the main sort on.
>
> However I added an IComparable called FindProdID and used the following
>
> myspec = new clsSpecs
> mySpec.ProdID = "100676"
> indx = specList.Binary Search(myspec, new FindProdID)
>
> and all worked well and returned the index it should have.
>
> Thanks for the pointer.
>[color=green]
> >
> >"John Veldthuis" <johnv@no.spamo .paradise.net.n z> wrote in message
> >news:man0l1lvf 15433qpv1fiqkaa dk1tei5ud7@4ax. com...[color=darkred]
> >>I have an ArrayList set up with a set of class objects.
> >>
> >> The class has 3 strings in it and are as follows
> >>
> >> ProdID
> >> GSP
> >> Description
> >>
> >> Okay now problem with getting all these into the list and displaying them
> >> correctly and manipulating
> >> things except for one thing.
> >>
> >> I wish to be able to do search through the whole list without stepping
> >> through the entire list
> >> enumerating them. I would just like to be able to search on one field. The
> >> ProdID.
> >>
> >> For now I do it by
> >>
> >> dim myspec as new clsSpecs
> >> for each myspec in specList
> >> if test.prodid.com pareto(myspec.P rodID) = 0 then
> >>
> >> do stuff
> >>
> >> end if
> >>
> >> next
> >>
> >>
> >> Now this works but I am looking for a search method but list.BinarySear ch
> >> does not seem to do it.
> >>
> >> Any help?[/color]
> >
> >I suggest you read this article:
> >
> >http://msdn.microsoft.com/library/de...archtopic1.asp
> >
> >You'll note that the objects in your ArrayList must come from a class that
> >implements the IComparable interface, and that the objects must be sorted
> >according to your IComparable implementation. Then the BinarySearch method
> >will yield the results you seek.[/color]
>[/color]

[John Veldthuis]

Re: ArrayList Search for Value

On Sat, 15 Oct 2005 06:01:02 -0700, Dennis <Dennis@discuss ions.microsoft. com> wrote:
[color=blue]
>Don't you have to sort the arraylist on the ProdID property first before
>using the binarysearch?[/color]

Yes, I simply resorted using the new IComparer and then did the search and then resorted back the
original.

[John Veldthuis]

Re: ArrayList Search for Value

On Sat, 15 Oct 2005 11:08:58 +0200, "Cor Ligthert [MVP]" <notmyfirstname @planet.nl> wrote:
[color=blue]
>John,
>
>If you are sure that you want to use the complete word in the exact cases,
>than you can use the arraylist indexof method
>
>http://msdn.microsoft.com/library/de...dexoftopic.asp
>
>If you want it undependable from the cases than you should be able to use
>the Icomparer as nicely described by Peter Proost, Jay B. Harlow and more
>people in this newsgroup this week
>
>http://groups.google.com/group/micro...9adf0d52e87dfc
>
>If you are the same John, than forget this message.
>
>I hope this helps,[/color]

Thanks, different John but I understood all that. My problem was that I did not just have a simple
entry as the example but a class and was unsure of how the binarysearch worked on only filling out
part of the class. However all fixed now and working 100% how I expected thanks to the help and
pointers from those here.