A visitor of types, in the style of the
visitor design pattern. Classes implementing this
interface are used to operate on a type when the kind of
type is unknown at compile time. When a visitor is passed to a
type's
accept
method, the
visitXYZ
method most applicable to that type is invoked.
Classes implementing this interface may or may not throw a
NullPointerException
if the additional parameter p
is 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.