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copied!<p>You can override <a href="http://wicket.apache.org/apidocs/1.4/org/apache/wicket/markup/html/form/AbstractSingleSelectChoice.html#getNullKey%28%29" rel="nofollow"><code>AbstractSingleSelectChoice.getNullKey()</code></a> and <a href="http://wicket.apache.org/apidocs/1.4/org/apache/wicket/markup/html/form/AbstractSingleSelectChoice.html#getNullValidKey%28%29" rel="nofollow"><code>AbstractSingleSelectChoice.getNullValidKey()</code></a> in order to make Wicket retrieve a localized resource from a .properties or .xml file that does not have the component id as part of the key. This is documented in this JIRA issue: <a href="https://issues.apache.org/jira/browse/WICKET-2531" rel="nofollow">Open DropDownChoice null value internationalization key</a></p> <p>For instance: </p> <pre><code>DropDownChoice ddc = new DropDownChoice(id, model, choices){ @Override protected String getNullKey(){ return "customDdcNullValue"; } @Override protected String getNullValidKey(){ return "customDdcNullValue"; } } </code></pre> <p>Will retrieve the <code><option></code>'s text from the <code>customDdcNullValue</code> property. </p> <p>These methods seem to have been added in version 1.4.4, if you're on 1.3, you could always use an <code>IChoiceRenderer</code> with the <code>DropDownChoice</code> that returns the proper String in the case of <code>null</code> value. Note that you could retrieve it from resources (with <code>getString()</code>, or <code>StringResourceModel</code>), or grab the value from database/cache if necessary. This may depend on how are you already localizing the choices for non-null values.</p> <p>Also, you could use the source code of <a href="http://grepcode.com/file/repo1.maven.org/maven2/org.apache.wicket/wicket/1.4.8/org/apache/wicket/markup/html/form/AbstractSingleSelectChoice.java#AbstractSingleSelectChoice.getDefaultChoice%28java.lang.Object%29" rel="nofollow"><code>AbstractSingleSelectChoice.getDefaultChoice()</code></a> to roll your own <code>DropDownChoice</code> with this behavior.</p> <p><strong>UPDATE</strong>: Another way of handling this is to provide your own custom value that represents <code>null</code>, or no-choice. Just remember to use <code>setNullValid(false)</code> on the <code>DropDownChoice</code> to prevent <code>null</code> from appearing when there is a selected value, and initialize the ddc's model with your no-selection value when you still don't know its value in order to avoid Wicket provide <code>null</code> in the <code>getDefaultChoice()</code> call. </p> <p>When defining the value for your no-selection option, pay special attention to this part of <a href="http://grepcode.com/file/repo1.maven.org/maven2/org.apache.wicket/wicket/1.4.8/org/apache/wicket/markup/html/form/AbstractSingleSelectChoice.java#301" rel="nofollow"><code>AbstractSingleSelectChoice.getDefaultChoice()</code></a>: </p> <pre><code>// Null is not valid. Is it selected anyway? if ((selected == null) || getNoSelectionValue().equals(selected) || selected.equals(EMPTY_STRING)) { </code></pre> <p>Take into account that <code>getNoSelectionValue()</code> returns <code>-1</code>, so please do not use <code>-1</code>, or an empty string, as your custom null value. I learnt this the hard way, believe me, it's not pleasing.</p>

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