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Posted to user@struts.apache.org by Vinita Keswani <vi...@yahoo.com> on 2003/11/17 19:11:33 UTC

How to iterate over two collections ?

Hello,
 
Could anyone please tell me if there is a workaround for iterating over two collections at the same time when both have the same key but different values?
 
For eg:  Descr, Cost,Volume....
Two maps one is - costMap which has descr and cost
and another one is - volMap which has descr and volume.
 
Please help
 
Vinita


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Re: How to iterate over two collections ?

Posted by Vinita Keswani <vi...@yahoo.com>.

Thanks again...
 
Yes I have to lookup using the key ..that will work fine..Thanks again.

Kris Schneider <kr...@dotech.com> wrote:
I think the code I provided does what you were asking for, but maybe I'm missing
something. Perhaps adding comments to my example will help:













Quoting Vinita Keswani :

> Thanks but in any case I have to create an iterator to loop thru the
> maps.What I want to do is to have one loop and to pick up value entries from
> another - yes may be I can try using lookups using key???
> 
> Kris Schneider wrote:With JSTL:
> 
> 
> 
> 
> 
> 
> Quoting Brice Ruth 
> :
> 
> > You could loop over one collection, exposing the varStatus, which 
> > contains the key, and use the key to look up in the second map ... I
> think?
> > 
> > Vinita Keswani wrote:
> > 
> > >Hello,
> > > 
> > >Could anyone please tell me if there is a workaround for iterating over
> two
> > collections at the same time when both have the same key but different
> > values?
> > > 
> > >For eg: Descr, Cost,Volume....
> > >Two maps one is - costMap which has descr and cost
> > >and another one is - volMap which has descr and volume.
> > > 
> > >Please help
> > > 
> > >Vinita
> > >
> > >
> > >---------------------------------
> > >Do you Yahoo!?
> > >Protect your identity with Yahoo! Mail AddressGuard
> > > 
> > >
> > 
> > -- 
> > Brice D. Ruth
> > Sr. IT Analyst
> > Fiskars Brands, Inc.
> 
> -- 
> Kris Schneider 
> D.O.Tech 

-- 
Kris Schneider 
D.O.Tech 

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Re: How to iterate over two collections ?

Posted by Kris Schneider <kr...@dotech.com>.

I think the code I provided does what you were asking for, but maybe I'm missing
something. Perhaps adding comments to my example will help:

<%-- iterate through costMap, "entry" will be an instance of Map.Entry --%>
<%-- Map.Entry exposes two properties: "key" and "value"               --%>
<c:forEach var="entry" items="${costMap}">

  <%-- output value for costMap entry --%>
  <c:out value="${entry.value}"/>

  <%-- output value for volMap entry --%>
  <c:out value="${volMap[entry.key]}"/>

</c:forEach>

Quoting Vinita Keswani <vi...@yahoo.com>:

> Thanks but in any case I have to create an iterator to loop thru the
> maps.What I want to do is to have one loop and to pick up value entries from
> another - yes may be I can try using lookups using key???
> 
> Kris Schneider <kr...@dotech.com> wrote:With JSTL:
> 
> 
> 
> 
> 
> 
> Quoting Brice Ruth 
> :
> 
> > You could loop over one collection, exposing the varStatus, which 
> > contains the key, and use the key to look up in the second map ... I
> think?
> > 
> > Vinita Keswani wrote:
> > 
> > >Hello,
> > > 
> > >Could anyone please tell me if there is a workaround for iterating over
> two
> > collections at the same time when both have the same key but different
> > values?
> > > 
> > >For eg: Descr, Cost,Volume....
> > >Two maps one is - costMap which has descr and cost
> > >and another one is - volMap which has descr and volume.
> > > 
> > >Please help
> > > 
> > >Vinita
> > >
> > >
> > >---------------------------------
> > >Do you Yahoo!?
> > >Protect your identity with Yahoo! Mail AddressGuard
> > > 
> > >
> > 
> > -- 
> > Brice D. Ruth
> > Sr. IT Analyst
> > Fiskars Brands, Inc.
> 
> -- 
> Kris Schneider 
> D.O.Tech 

-- 
Kris Schneider <ma...@dotech.com>
D.O.Tech       <http://www.dotech.com/>

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Re: How to iterate over two collections ?

Posted by Vinita Keswani <vi...@yahoo.com>.

Thanks but in any case I have to create an iterator to loop thru the maps.What I want to do is to have one loop and to pick up value entries from another - yes may be I can try using lookups using key???

Kris Schneider <kr...@dotech.com> wrote:With JSTL:






Quoting Brice Ruth 
:

> You could loop over one collection, exposing the varStatus, which 
> contains the key, and use the key to look up in the second map ... I think?
> 
> Vinita Keswani wrote:
> 
> >Hello,
> > 
> >Could anyone please tell me if there is a workaround for iterating over two
> collections at the same time when both have the same key but different
> values?
> > 
> >For eg: Descr, Cost,Volume....
> >Two maps one is - costMap which has descr and cost
> >and another one is - volMap which has descr and volume.
> > 
> >Please help
> > 
> >Vinita
> >
> >
> >---------------------------------
> >Do you Yahoo!?
> >Protect your identity with Yahoo! Mail AddressGuard
> > 
> >
> 
> -- 
> Brice D. Ruth
> Sr. IT Analyst
> Fiskars Brands, Inc.

-- 
Kris Schneider 
D.O.Tech 

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Re: How to iterate over two collections ?

Posted by Kris Schneider <kr...@dotech.com>.

With JSTL:

<c:forEach var="entry" items="${costMap}">
  <c:out value="${entry.value}"/>
  <c:out value="${volMap[entry.key]}"/>
</c:forEach>

Quoting Brice Ruth <br...@fiskars.com>:

> You could loop over one collection, exposing the varStatus, which 
> contains the key, and use the key to look up in the second map ... I think?
> 
> Vinita Keswani wrote:
> 
> >Hello,
> > 
> >Could anyone please tell me if there is a workaround for iterating over two
> collections at the same time when both have the same key but different
> values?
> > 
> >For eg:  Descr, Cost,Volume....
> >Two maps one is - costMap which has descr and cost
> >and another one is - volMap which has descr and volume.
> > 
> >Please help
> > 
> >Vinita
> >
> >
> >---------------------------------
> >Do you Yahoo!?
> >Protect your identity with Yahoo! Mail AddressGuard
> >  
> >
> 
> -- 
> Brice D. Ruth
> Sr. IT Analyst
> Fiskars Brands, Inc.

-- 
Kris Schneider <ma...@dotech.com>
D.O.Tech       <http://www.dotech.com/>

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Re: How to iterate over two collections ?

Posted by Brice Ruth <br...@fiskars.com>.

You could loop over one collection, exposing the varStatus, which 
contains the key, and use the key to look up in the second map ... I think?

Vinita Keswani wrote:

>Hello,
> 
>Could anyone please tell me if there is a workaround for iterating over two collections at the same time when both have the same key but different values?
> 
>For eg:  Descr, Cost,Volume....
>Two maps one is - costMap which has descr and cost
>and another one is - volMap which has descr and volume.
> 
>Please help
> 
>Vinita
>
>
>---------------------------------
>Do you Yahoo!?
>Protect your identity with Yahoo! Mail AddressGuard
>  
>

-- 
Brice D. Ruth
Sr. IT Analyst
Fiskars Brands, Inc.



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Re: How to iterate over two collections ?

Posted by Rick Reumann <st...@reumann.net>.

Vinita Keswani wrote:

> Hello,
> 
> Could anyone please tell me if there is a workaround for iterating
> over two collections at the same time when both have the same key but
> different values?
> 
> For eg:  Descr, Cost,Volume.... Two maps one is - costMap which has
> descr and cost and another one is - volMap which has descr and
> volume.

Here's an example using JSTL that I just tested...

<%
java.util.HashMap costMap = new java.util.HashMap();
costMap.put( "foo", "costFoo" );
costMap.put( "bar", "costBar" );

java.util.HashMap volMap = new java.util.HashMap();
volMap.put( "foo", "volFoo" );
volMap.put( "bar", "volBar" );

pageContext.setAttribute("costMap", costMap );
pageContext.setAttribute("volMap", volMap );
%>

<c:forEach items="${costMap}" var="costItem">
     Cost Desc: <c:out value="${costItem.key}"/><br>
     Cost Value: <c:out value="${costItem.value}"/><br>
     Vol Value: <c:out value="${volMap[costItem.key]}"/><br>
     ----<br>
</c:forEach>
-- 
Rick


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