spring bind field based on other selection

[alex lio]

hello
how can i bind the form:options based on another option field?
in example i have combobox for country and i want to get all the cities based on the country selected

<tr>
                <td>Country:</td>
                <td><select id="country" name="country">
                    <option value="US">United Stated</option>
                    <option value="CHINA">China</option>
                    <option value="SG">Singapore</option>
                    <option value="MY">Malaysia</option>
                </select></td>
            </tr>
        <tr>
            <td>city:</td>
            <td>
                 <form:select path="cityList" multiple="false" >
                        <form:option value="-" label="--Please Select"/>
                        <form:options items="${cityList}"/>
                    </form:select>

            </td>