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From: Chris Riesbeck <Chris.Riesbeck@gmail.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: JSTL: getting a map's keys
Date: Tue, 20 Mar 2012 12:52:46 -0500
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On 3/20/2012 12:19 PM, Chris Riesbeck wrote:
> On 3/19/2012 6:59 PM, Daniel Pitts wrote:
>> On 3/19/12 11:15 AM, Chris Riesbeck wrote:
>>>
>>> [summary: rates is an instance of a subclass of Map that
 >>>  implements getKeys()]
>>>
>>> Why does ${rates.keys} generate nothing in these lines of JSP?
>>>
>> My guess is that ${rates.keys} is interpreted as equivalent to
>> ${rates['keys']}, so it is looking for a key of "keys", not a java bean
>> property.

Just to nail the coffin lid shut on this. The JSP EL defines name.key as 
just shorthand for name["key"]. To interpret [] expressions, JSP uses 
the first answer it gets from this chain of resolvers:

     ImplicitObjectELResolver
     registered custom ELResolvers
     MapELResolver
     ListELResolver
     ArrayELResolver
     BeanELResolver
     ScopedAttributeELResolver

 
http://docs.oracle.com/javaee/5/api/javax/servlet/jsp/JspApplicationContext.html

So the Map interpretation will always override the Bean interpretation.