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POAccess TreeMap entries by string key in JSTL
 

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  1. POAccess TreeMap entries by string key in JSTL
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    <p>This is pretty similar to some other questions, but nobody else is working with string keys. So here we go.</p> <p>I've got a TreeMap with a set of category names, keyed by category ID. The ID is a number (as a String).</p> <p>I build up the TreeMap with values, then expose it to the page, like so:</p> <pre><code>&lt;% Map categories = new TreeMap(); ... String categoryId = ...; String categoryName = ...; categories.put(categoryId, categoryName); ... pageContext.setAttribute("categories", categories); %&gt; </code></pre> <p>Later, I iterate through a series of items which have been assigned to categories. Each item has a .categories collection which contains the IDs of the categories to which it has been assigned. I want to display the names, so I do something like this:</p> <pre><code>&lt;c:forEach items="${item.categories}" var="catId"&gt; ${categories[“${catId}”} &lt;/c:forEach&gt; </code></pre> <p>Unfortunately, this doesn't emit anything. Nor does <code>${categories["${catId}"].value}.</code></p> <p>However, this does:</p> <pre><code>${categories["2"]} </code></pre> <p>Of course, that line isn't actually driven by item data.</p> <p>I've checked, and the IDs attached to each item do in fact correspond to category IDs; this isn't a data mismatch problem.</p> <p>So, how do I get my hands on category names when the data attached to items has only IDs?</p> <p>P.S. I should mention that I'm not a Java programmer -- at all. LAMP is more my style. So modifying classes isn't really an option.</p>
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