STRUTS2标签错误

org.apache.jasper.JasperException: tag 'select', field 'list': The requested list key 'secondList' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]//在用 <s:select标签的时候，报了一个这样的错误，后来才知道是ACTION里没有写属性的get()set()方法……