Interface TypeVisitor<R,P>
- 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.
- API Note:
-
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. Such additions have already occurred to support language features added after this API was introduced. 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.
Methods to accommodate new language constructs are expected to be added as default methods to provide strong source compatibility. The implementations of the default methods will in turn call
visitUnknown
, behavior that will be overridden in concrete visitors supporting the source version with the new language construct.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 |
A convenience method equivalent to visit(t, null) . |
R |
visit |
Visits a type. |
R |
visitArray |
Visits an array type. |
R |
visitDeclared |
Visits a declared type. |
R |
visitError |
Visits an error type. |
R |
visitExecutable |
Visits an executable type. |
R |
visitIntersection |
Visits an intersection type. |
R |
visitNoType |
Visits a NoType instance. |
R |
visitNull |
Visits the null type. |
R |
visitPrimitive |
Visits a primitive type. |
R |
visitTypeVariable |
Visits a type variable. |
R |
visitUnion |
Visits a union type. |
R |
visitUnknown |
Visits an unknown kind of type. |
R |
visitWildcard |
Visits a wildcard type. |
Method Details
visit
R visit(TypeMirror t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visit
default R visit(TypeMirror t)
visit(t, null)
.- Implementation Requirements:
- The default implementation is
visit(t, null)
. - Parameters:
-
t
- the element to visit - Returns:
- a visitor-specified result
visitPrimitive
R visitPrimitive(PrimitiveType t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visitNull
R visitNull(NullType t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visitArray
R visitArray(ArrayType t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visitDeclared
R visitDeclared(DeclaredType t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visitError
R visitError(ErrorType t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visitTypeVariable
R visitTypeVariable(TypeVariable t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visitWildcard
R visitWildcard(WildcardType t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visitExecutable
R visitExecutable(ExecutableType t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visitNoType
R visitNoType(NoType t, P p)
NoType
instance.- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
visitUnknown
R visitUnknown(TypeMirror t, P p)
TypeMirror
hierarchy.- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
- Throws:
-
UnknownTypeException
- a visitor implementation may optionally throw this exception
visitUnion
R visitUnion(UnionType t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
- Since:
- 1.7
visitIntersection
R visitIntersection(IntersectionType t, P p)
- Parameters:
-
t
- the type to visit -
p
- a visitor-specified parameter - Returns:
- a visitor-specified result
- Since:
- 1.8
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/17/docs/api/java.compiler/javax/lang/model/type/TypeVisitor.html