Comment voulez-vous obtenir les valeurs à partir d'une liste déroulante dans Wicket?

J'ai trouvé ce qui suit Guichet exemple de 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<String, List<String>> modelsMap = new HashMap<String, List<String>>(); //map:company->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<List<? extends String>> makeChoices = new AbstractReadOnlyModel<List<? extends String>>()
{
@Override
public List<String> getObject()
{
Set<String> keys = modelsMap.keySet();
List<String> list = new ArrayList<String>(keys);
return list;
}
};
IModel<List<? extends String>> modelChoices = new AbstractReadOnlyModel<List<? extends String>>()
{
@Override
public List<String> getObject()
{
List<String> models = modelsMap.get(selectedMake);
if (models == null)
{
models = Collections.emptyList();
}
return models;
}
};
Form<?> form = new Form("form");
add(form);
final DropDownChoice<String> makes = new DropDownChoice<String>("makes",
new PropertyModel<String>(this, "selectedMake"), makeChoices);
final DropDownChoice<String> models = new DropDownChoice<String>("models",
new Model<String>(), modelChoices);
models.setOutputMarkupId(true);
form.add(makes);
form.add(models);
makes.add(new AjaxFormComponentUpdatingBehavior("onchange")
{
@Override
protected void onUpdate(AjaxRequestTarget target)
{
target.addComponent(models);
}
});
}
}

Supposons que j'ai la classe suivante:

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...
}

Je veux créer un car objet dans l'exemple de code, et d'assigner les valeurs sélectionnées dans la liste déroulante de la car objet. Comment puis-je le faire?