This tag evaluates its nested body content only if the specified value
is either absent (i.e. null
), an empty string (i.e. a
java.lang.String
with a length of zero), or an empty
java.util.Collection
or java.util.Map
(tested by
the .isEmpty() method on the respective interface).
JSTL: The equivalent JSTL tag is <c:if> using the
empty
operator. For example,
<c:if test="${empty sessionScope.myBean.myProperty}">
do something
</c:if>
Since: Struts 1.1