title: How do you get values from a dropdown list in Wicket?
body: <p>I've found the following Wicket sample code:</p>
  
  <pre><code>package org.apache.wicket.examples.ajax.builtin;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.wicket.ajax.AjaxRequestTarget;
  import org.apache.wicket.ajax.form.AjaxFormComponentUpdatingBehavior;
  import org.apache.wicket.markup.html.form.DropDownChoice;
  import org.apache.wicket.markup.html.form.Form;
  import org.apache.wicket.model.AbstractReadOnlyModel;
  import org.apache.wicket.model.IModel;
  import org.apache.wicket.model.Model;
  import org.apache.wicket.model.PropertyModel;
  
  /**
   * Linked select boxes example
   * 
   * @author Igor Vaynberg (ivaynberg)
   */
  public class ChoicePage extends BasePage
  {
      private String selectedMake;
  
      private final Map&lt;String, List&lt;String&gt;&gt; modelsMap = new HashMap&lt;String, List&lt;String&gt;&gt;(); // map:company-&gt;model
  
      /**
       * @return Currently selected make
       */
      public String getSelectedMake()
      {
          return selectedMake;
      }
  
      /**
       * @param selectedMake
       *            The make that is currently selected
       */
      public void setSelectedMake(String selectedMake)
      {
          this.selectedMake = selectedMake;
      }
  
      /**
       * Constructor.
       */
      public ChoicePage()
      {
          modelsMap.put("AUDI", Arrays.asList(new String[] { "A4", "A6", "TT" }));
          modelsMap.put("CADILLAC", Arrays.asList(new String[] { "CTS", "DTS", "ESCALADE", "SRX",
                  "DEVILLE" }));
          modelsMap.put("FORD", Arrays.asList(new String[] { "CROWN", "ESCAPE", "EXPEDITION",
                  "EXPLORER", "F-150" }));
  
          IModel&lt;List&lt;? extends String&gt;&gt; makeChoices = new AbstractReadOnlyModel&lt;List&lt;? extends String&gt;&gt;()
          {
              @Override
              public List&lt;String&gt; getObject()
              {
                  Set&lt;String&gt; keys = modelsMap.keySet();
                  List&lt;String&gt; list = new ArrayList&lt;String&gt;(keys);
                  return list;
              }
  
          };
  
          IModel&lt;List&lt;? extends String&gt;&gt; modelChoices = new AbstractReadOnlyModel&lt;List&lt;? extends String&gt;&gt;()
          {
              @Override
              public List&lt;String&gt; getObject()
              {
                  List&lt;String&gt; models = modelsMap.get(selectedMake);
                  if (models == null)
                  {
                      models = Collections.emptyList();
                  }
                  return models;
              }
  
          };
  
          Form&lt;?&gt; form = new Form("form");
          add(form);
  
          final DropDownChoice&lt;String&gt; makes = new DropDownChoice&lt;String&gt;("makes",
              new PropertyModel&lt;String&gt;(this, "selectedMake"), makeChoices);
  
          final DropDownChoice&lt;String&gt; models = new DropDownChoice&lt;String&gt;("models",
              new Model&lt;String&gt;(), modelChoices);
          models.setOutputMarkupId(true);
  
          form.add(makes);
          form.add(models);
  
          makes.add(new AjaxFormComponentUpdatingBehavior("onchange")
          {
              @Override
              protected void onUpdate(AjaxRequestTarget target)
              {
                  target.addComponent(models);
              }
          });
      }
  }
  </code></pre>
  
  <p>Suppose I have the following class:</p>
  
  <pre><code>public class car{
        private String name;
        private String  model;
  
        public setname(String n){
             this.name=n;
        }
        public setModel(String m){
             this.model=m;
        }
        ///  and getters...
  }
  </code></pre>
  
  <p>I want to create a <code>car</code> object in the sample code, and assign the values selected in the dropdown to the <code>car</code> object. How can I do that?</p>