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JavaRanch » Java Forums » Certification » Web Component Certification (SCWCD/OCPJWCD)
Bookmark "EL concatenation -> ${map[ ?+? ]}" Watch "EL concatenation -> ${map[ ?+? ]}" New topic
Author

EL concatenation -> ${map[ ?+? ]}

Dimiter Stoinov
Greenhorn

Joined: Jul 06, 2004
Posts: 3
Hi guys,

Have the following snippet:

<jsp:useBean id="map" class="java.util.HashMap"/>
<%
map.put("a123", "object");
pageContext.setAttribute( "id", "123" );
%>
${map[ 'a' + id ]}


Trying to concat 'a' with some existing attribute to get the map value. No success so far. How can i concat values inside the [] brackets?

Can you give me a hint please.

Thank's for your time
Leena Diwan
Ranch Hand

Joined: Jun 18, 2001
Posts: 351
Im not sure about it but did u try it with String rather than char?
You can try ["a"+123].

Regards,
Leena


[SCJP2, SCWCD1.3, SCBCD]
Dimiter Stoinov
Greenhorn

Joined: Jul 06, 2004
Posts: 3
Problem is that + is used for addition so "a"+"somethingelse" else gives plenty nice errors of type:
javax.servlet.ServletException: An exception occured trying to convert String "a1" to type "java.lang.Long" / or "java.lang.Double"

Following code is solution, but i rather wanted the concatenation inside the [ ] brackets

<jsp:useBean id="map" class="java.util.HashMap"/>
<%
map.put( "a123", "object");

final String s = "a" + "123";
pageContext.setAttribute( "id", s );
%>

${map[ id ]}


[ July 07, 2004: Message edited by: Dimiter Stoinov ]
 
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subject: EL concatenation -> ${map[ ?+? ]}