- Type Parameters:
R
- the return type of this visitor's methods. UseVoid
for visitors that do not need to return results.P
- the type of the additional parameter to this visitor's methods. UseVoid
for visitors that do not need an additional parameter.
- All Known Implementing Classes:
AbstractTypeVisitor14
,AbstractTypeVisitor6
,AbstractTypeVisitor7
,AbstractTypeVisitor8
,AbstractTypeVisitor9
,SimpleTypeVisitor14
,SimpleTypeVisitor6
,SimpleTypeVisitor7
,SimpleTypeVisitor8
,SimpleTypeVisitor9
,TypeKindVisitor14
,TypeKindVisitor6
,TypeKindVisitor7
,TypeKindVisitor8
,TypeKindVisitor9
public interface TypeVisitor<R,P>
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.
Note that methods to accommodate new language constructs could
be added in a source compatible way if they were added as
default methods. However, default methods are only
available on Java SE 8 and higher releases and the
javax.lang.model.*
packages bundled in Java SE 8 were required to
also be runnable on Java SE 7. Therefore, default methods
were not used when extending javax.lang.model.*
to cover Java SE 8 language features. However, default methods
are used in subsequent revisions of the javax.lang.model.*
packages that are only required to run on Java SE 8 and higher
platform versions.
- API Note:
- There are several families of classes implementing this visitor
interface in the util
package. The families follow a naming pattern along the lines of
FooVisitor
N where N indicates the source version the visitor is appropriate for. In particular, aFooVisitor
N is expected to handle all language constructs present in source version N. If there are no new language constructs added in version N + 1 (or subsequent releases),FooVisitor
N may also handle that later source version; in that case, theSupportedSourceVersion
annotation on theFooVisitor
N class will indicate a later version. When visiting a type representing a language construct introduced after source version N, aFooVisitor
N will throw anUnknownTypeException
unless that behavior is overridden.When choosing which member of a visitor family to subclass, subclassing the most recent one increases the range of source versions covered. When choosing which visitor family to subclass, consider their built-in capabilities:
AbstractTypeVisitor
s: Skeletal visitor implementations.SimpleTypeVisitor
s: Support default actions and a default return value.TypeKindVisitor
s: Visit methods provided on a per-kind granularity as some categories of types can have more than one kind.
- Since:
- 1.6
-
Method Summary
Modifier and Type Method Description default R
visit(TypeMirror t)
A convenience method equivalent tovisit(t, null)
.R
visit(TypeMirror t, P p)
Visits a type.R
visitArray(ArrayType t, P p)
Visits an array type.R
visitDeclared(DeclaredType t, P p)
Visits a declared type.R
visitError(ErrorType t, P p)
Visits an error type.R
visitExecutable(ExecutableType t, P p)
Visits an executable type.R
visitIntersection(IntersectionType t, P p)
Visits an intersection type.R
visitNoType(NoType t, P p)
Visits aNoType
instance.R
visitNull(NullType t, P p)
Visits the null type.R
visitPrimitive(PrimitiveType t, P p)
Visits a primitive type.R
visitTypeVariable(TypeVariable t, P p)
Visits a type variable.R
visitUnion(UnionType t, P p)
Visits a union type.R
visitUnknown(TypeMirror t, P p)
Visits an unknown kind of type.R
visitWildcard(WildcardType t, P p)
Visits a wildcard type.
-
Method Details
-
visit
Visits a type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visit
A convenience method equivalent tovisit(t, null)
.- Implementation Requirements:
- The default implementation is
visit(t, null)
. - Parameters:
t
- the element to visit- Returns:
- a visitor-specified result
-
visitPrimitive
Visits a primitive type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visitNull
Visits the null type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visitArray
Visits an array type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visitDeclared
Visits a declared type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visitError
Visits an error type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visitTypeVariable
Visits a type variable.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visitWildcard
Visits a wildcard type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visitExecutable
Visits an executable type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visitNoType
Visits aNoType
instance.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
-
visitUnknown
Visits an unknown kind of type. This can occur if the language evolves and new kinds of types are added to theTypeMirror
hierarchy.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
- Throws:
UnknownTypeException
- a visitor implementation may optionally throw this exception
-
visitUnion
Visits a union type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
- Since:
- 1.7
-
visitIntersection
Visits an intersection type.- Parameters:
t
- the type to visitp
- a visitor-specified parameter- Returns:
- a visitor-specified result
- Since:
- 1.8
-