| A visitor of program elements, in the style of the visitor design
pattern. Classes implementing this interface are used to operate
on an element when the kind of element is unknown at compile time.
When a visitor is passed to an element's {@link Element#accept
accept} method, the visitXYZ method most applicable
to that element is invoked.
Classes implementing this interface may or may not throw a
{@code NullPointerException} if the additional parameter {@code p}
is {@code null}; see documentation of the implementing class for
details.
WARNING: It is possible that methods will be added to
this interface to accommodate new, currently unknown, language
structures added to future versions of the Java™ programming
language. Therefore, visitor classes directly implementing this
interface may be source incompatible with future versions of the
platform. To avoid this source incompatibility, visitor
implementations are encouraged to instead extend the appropriate
abstract visitor class that implements this interface. However, an
API should generally use this visitor interface as the type for
parameters, return type, etc. rather than one of the abstract
classes. |
