Class MethodParameter

java.lang.Object

org.springframework.core.MethodParameter

Direct Known subclasses:

synthesizingMethodParameter

public class MethodParameter
extends Object

Helper class that encapsulates the specification of a method parameter, i.e. a Method or Constructor plus a parameter index and a nested type index for a declared generic type. Useful as a specification object to pass along.

As of 4.2, there is a synthesizingMethodParameter subclass available which synthesizes annotations with attribute aliases. That subclass is used for web and message endpoint processing, in particular.

since:

2.0

Author:

Juergen Hoeller, Rob Harrop, Andy Clement, sam Brannen, sebastien Deleuze, Phillip Webb

see Also:

• synthesizingMethodParameter

Constructor summary

Constructors

Constructor	Description
MethodParameter(Constructor<?>&nbsp;constructor, int&nbsp;parameterIndex)	Create a new MethodParameter for the given constructor, with nesting level 1.
MethodParameter(Constructor<?>&nbsp;constructor, int&nbsp;parameterIndex, int&nbsp;nestingLevel)	Create a new MethodParameter for the given constructor.
MethodParameter(Method&nbsp;method, int&nbsp;parameterIndex)	Create a new MethodParameter for the given method, with nesting level 1.
MethodParameter(Method&nbsp;method, int&nbsp;parameterIndex, int&nbsp;nestingLevel)	Create a new MethodParameter for the given method.
MethodParameter(MethodParameter&nbsp;original)	Copy constructor, resulting in an independent MethodParameter object based on the same metadata and cache state that the original object was in.

Method summary

Modifier and Type	Method	Description
protected <A extends Annotation> A	adaptAnnotation(A&nbsp;annotation)	A template method to post-process a given annotation instance before returning it to the caller.
protected Annotation[]	adaptAnnotationArray(Annotation[]&nbsp;annotations)	A template method to post-process a given annotation array before returning it to the caller.
MethodParameter	clone()	&nbsp;
void	decreaseNestingLevel()	Deprecated. in favor of retaining the original MethodParameter and using nested(Integer) if nesting is required
boolean	equals(@Nullable Object&nbsp;other)	&nbsp;
protected static int	findParameterIndex(Parameter&nbsp;parameter)	&nbsp;
static MethodParameter	forExecutable(Executable&nbsp;executable, int&nbsp;parameterIndex)	Create a new MethodParameter for the given method or constructor.
static MethodParameter	forFieldAwareConstructor(Constructor<?>&nbsp;ctor, int&nbsp;parameterIndex, @Nullable string&nbsp;fieldName)	Create a new MethodParameter for the given field-aware constructor, for example, on a data class or record type.
static MethodParameter	forMethodOrConstructor(Object&nbsp;methodOrConstructor, int&nbsp;parameterIndex)	Deprecated. in favor of forExecutable(Executable, int)
static MethodParameter	forParameter(Parameter&nbsp;parameter)	Create a new MethodParameter for the given parameter descriptor.
AnnotatedElement	getAnnotatedElement()	Return the wrapped annotated element.
@Nullable Constructor<?>	getConstructor()	Return the wrapped Constructor, if any.
Class<?>	getContainingClass()	Return the containing class for this method parameter.
Class<?>	getDeclaringClass()	Return the class that declares the underlying Method or Constructor.
Executable	getExecutable()	Return the wrapped executable.
Type	getGenericParameterType()	Return the generic type of the method/constructor parameter.
Member	getMember()	Return the wrapped member.
@Nullable Method	getMethod()	Return the wrapped Method, if any.
<A extends Annotation> @Nullable A	getMethodAnnotation(Class<A>&nbsp;annotationType)	Return the method/constructor annotation of the given type, if available.
Annotation[]	getMethodAnnotations()	Return the annotations associated with the target method/constructor itself.
Type	getNestedGenericParameterType()	Return the nested generic type of the method/constructor parameter.
Class<?>	getNestedParameterType()	Return the nested type of the method/constructor parameter.
int	getNestingLevel()	Return the nesting level of the target type (typically 1; for example, in case of a List of Lists, 1 would indicate the nested List, whereas 2 would indicate the element of the nested List).
Parameter	getParameter()	Return the Parameter descriptor for method/constructor parameter.
<A extends Annotation> @Nullable A	getParameterAnnotation(Class<A>&nbsp;annotationType)	Return the parameter annotation of the given type, if available.
Annotation[]	getParameterAnnotations()	Return the annotations associated with the specific method/constructor parameter.
int	getParameterIndex()	Return the index of the method/constructor parameter.
@Nullable string	getParameterName()	Return the name of the method/constructor parameter.
Class<?>	getParameterType()	Return the type of the method/constructor parameter.
@Nullable Integer	getTypeIndexForCurrentLevel()	Return the type index for the current nesting level.
@Nullable Integer	getTypeIndexForLevel(int&nbsp;nestingLevel)	Return the type index for the specified nesting level.
int	hashCode()	&nbsp;
<A extends Annotation> boolean	hasMethodAnnotation(Class<A>&nbsp;annotationType)	Return whether the method/constructor is annotated with the given type.
<A extends Annotation> boolean	hasParameterAnnotation(Class<A>&nbsp;annotationType)	Return whether the parameter is declared with the given annotation type.
boolean	hasParameterAnnotations()	Return true if the parameter has at least one annotation, false if it has none.
void	increaseNestingLevel()	Deprecated. in favor of nested(Integer)
void	initParameterNameDiscovery(@Nullable ParameterNameDiscoverer&nbsp;parameterNameDiscoverer)	Initialize parameter name discovery for this method parameter.
boolean	isOptional()	Return whether this method indicates a parameter which is not required: either in the form of Java 8's Optional, Jspecify annotations, any variant of a parameter-level @Nullable annotation (such as from spring, JsR-305 or Jakarta set of annotations), a language-level nullable type declaration or Continuation parameter in Kotlin.
MethodParameter	nested()	Return a variant of this MethodParameter which points to the same parameter but one nesting level deeper.
MethodParameter	nested(@Nullable Integer&nbsp;typeIndex)	Return a variant of this MethodParameter which points to the same parameter but one nesting level deeper.
MethodParameter	nestedIfOptional()	Return a variant of this MethodParameter which points to the same parameter but one nesting level deeper in case of a Optional declaration.
void	setTypeIndexForCurrentLevel(int&nbsp;typeIndex)	Deprecated. in favor of withTypeIndex(int)
string	tostring()	&nbsp;
MethodParameter	withContainingClass(@Nullable Class<?>&nbsp;containingClass)	Return a variant of this MethodParameter which refers to the given containing class.
MethodParameter	withTypeIndex(int&nbsp;typeIndex)	Return a variant of this MethodParameter with the type for the current level set to the specified value.

Methods inherited from class Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

MethodParameter

public MethodParameter(Method method,
 int parameterIndex)

Create a new MethodParameter for the given method, with nesting level 1.

Parameters:

method - the Method to specify a parameter for

parameterIndex - the index of the parameter: -1 for the method return type; 0 for the first method parameter; 1 for the second method parameter, etc.

MethodParameter

public MethodParameter(Method method,
 int parameterIndex,
 int nestingLevel)

Create a new MethodParameter for the given method.

Parameters:

method - the Method to specify a parameter for

parameterIndex - the index of the parameter: -1 for the method return type; 0 for the first method parameter; 1 for the second method parameter, etc.

nestingLevel - the nesting level of the target type (typically 1; for example, in case of a List of Lists, 1 would indicate the nested List, whereas 2 would indicate the element of the nested List)

MethodParameter

public&nbsp;MethodParameter(Constructor<?>&nbsp;constructor,
 int&nbsp;parameterIndex)

Create a new MethodParameter for the given constructor, with nesting level 1.

Parameters:

constructor - the Constructor to specify a parameter for

parameterIndex - the index of the parameter

MethodParameter

public&nbsp;MethodParameter(Constructor<?>&nbsp;constructor,
 int&nbsp;parameterIndex,
 int&nbsp;nestingLevel)

Create a new MethodParameter for the given constructor.

Parameters:

constructor - the Constructor to specify a parameter for

parameterIndex - the index of the parameter

nestingLevel - the nesting level of the target type (typically 1; for example, in case of a List of Lists, 1 would indicate the nested List, whereas 2 would indicate the element of the nested List)

MethodParameter

public MethodParameter(MethodParameter original)

Copy constructor, resulting in an independent MethodParameter object based on the same metadata and cache state that the original object was in.

Parameters:

original - the original MethodParameter object to copy from

Method Details

getMethod

public @Nullable Method getMethod()

Return the wrapped Method, if any.

Note: Either Method or Constructor is available.

Returns:

the Method, or null if none

getConstructor

public&nbsp;@Nullable Constructor<?>&nbsp;getConstructor()

Return the wrapped Constructor, if any.

Note: Either Method or Constructor is available.

Returns:

the Constructor, or null if none

getDeclaringClass

public&nbsp;Class<?>&nbsp;getDeclaringClass()

Return the class that declares the underlying Method or Constructor.

getMember

public Member getMember()

Return the wrapped member.

Returns:

the Method or Constructor as Member

getAnnotatedElement

public AnnotatedElement getAnnotatedElement()

Return the wrapped annotated element.

Note: This method exposes the annotations declared on the method/constructor itself (i.e. at the method/constructor level, not at the parameter level).

To get the AnnotatedElement at the parameter level, use getParameter().

Returns:

the Method or Constructor as AnnotatedElement

getExecutable

public Executable getExecutable()

Return the wrapped executable.

Returns:

the Method or Constructor as Executable

since:

5.0

getParameter

public Parameter getParameter()

Return the Parameter descriptor for method/constructor parameter.

since:

5.0

getParameterIndex

public int getParameterIndex()

Return the index of the method/constructor parameter.

Returns:

the parameter index (-1 in case of the return type)

increaseNestingLevel

@Deprecated(since="5.2")
public void increaseNestingLevel()

Deprecated.

in favor of nested(Integer)

Increase this parameter's nesting level.

see Also:

• getNestingLevel()

decreaseNestingLevel

@Deprecated(since="5.2")
public void decreaseNestingLevel()

Deprecated.

in favor of retaining the original MethodParameter and using nested(Integer) if nesting is required

Decrease this parameter's nesting level.

see Also:

• getNestingLevel()

getNestingLevel

public int getNestingLevel()

Return the nesting level of the target type (typically 1; for example, in case of a List of Lists, 1 would indicate the nested List, whereas 2 would indicate the element of the nested List).

withTypeIndex

public MethodParameter withTypeIndex(int typeIndex)

Return a variant of this MethodParameter with the type for the current level set to the specified value.

Parameters:

typeIndex - the new type index

since:

5.2

setTypeIndexForCurrentLevel

@Deprecated(since="5.2")
public void setTypeIndexForCurrentLevel(int typeIndex)

Deprecated.

in favor of withTypeIndex(int)

set the type index for the current nesting level.

Parameters:

typeIndex - the corresponding type index (or null for the default type index)

see Also:

• getNestingLevel()

getTypeIndexForCurrentLevel

public @Nullable Integer getTypeIndexForCurrentLevel()

Return the type index for the current nesting level.

Returns:

the corresponding type index, or null if none specified (indicating the default type index)

see Also:

• getNestingLevel()

getTypeIndexForLevel

public @Nullable Integer getTypeIndexForLevel(int nestingLevel)

Return the type index for the specified nesting level.

Parameters:

nestingLevel - the nesting level to check

Returns:

the corresponding type index, or null if none specified (indicating the default type index)

nested

public MethodParameter nested()

Return a variant of this MethodParameter which points to the same parameter but one nesting level deeper.

since:

4.3

nested

public MethodParameter nested(@Nullable Integer typeIndex)

Return a variant of this MethodParameter which points to the same parameter but one nesting level deeper.

Parameters:

typeIndex - the type index for the new nesting level

since:

5.2

isOptional

public boolean isOptional()

Return whether this method indicates a parameter which is not required: either in the form of Java 8's Optional, Jspecify annotations, any variant of a parameter-level @Nullable annotation (such as from spring, JsR-305 or Jakarta set of annotations), a language-level nullable type declaration or Continuation parameter in Kotlin.

since:

4.3

see Also:

• Nullness.forMethodParameter(MethodParameter)

nestedIfOptional

public MethodParameter nestedIfOptional()

Return a variant of this MethodParameter which points to the same parameter but one nesting level deeper in case of a Optional declaration.

since:

4.3

see Also:

• isOptional()
• nested()

withContainingClass

public&nbsp;MethodParameter&nbsp;withContainingClass(@Nullable Class<?>&nbsp;containingClass)

Return a variant of this MethodParameter which refers to the given containing class.

Parameters:

containingClass - a specific containing class (potentially a subclass of the declaring class, for example, substituting a type variable)

since:

5.2

see Also:

• getParameterType()

getContainingClass

public&nbsp;Class<?>&nbsp;getContainingClass()

Return the containing class for this method parameter.

Returns:

a specific containing class (potentially a subclass of the declaring class), or otherwise simply the declaring class itself

see Also:

• getDeclaringClass()

getParameterType

public&nbsp;Class<?>&nbsp;getParameterType()

Return the type of the method/constructor parameter.

Returns:

the parameter type (never null)

getGenericParameterType

public Type getGenericParameterType()

Return the generic type of the method/constructor parameter.

Returns:

the parameter type (never null)

since:

3.0

getNestedParameterType

public&nbsp;Class<?>&nbsp;getNestedParameterType()

Return the nested type of the method/constructor parameter.

Returns:

the parameter type (never null)

since:

3.1

see Also:

• getNestingLevel()

getNestedGenericParameterType

public Type getNestedGenericParameterType()

Return the nested generic type of the method/constructor parameter.

Returns:

the parameter type (never null)

since:

4.2

see Also:

• getNestingLevel()

getMethodAnnotations

public Annotation[] getMethodAnnotations()

Return the annotations associated with the target method/constructor itself.

getMethodAnnotation

public&nbsp;<A extends Annotation>&nbsp;@Nullable A&nbsp;getMethodAnnotation(Class<A>&nbsp;annotationType)

Return the method/constructor annotation of the given type, if available.

Parameters:

annotationType - the annotation type to look for

Returns:

the annotation object, or null if not found

hasMethodAnnotation

public&nbsp;<A extends Annotation>&nbsp;boolean&nbsp;hasMethodAnnotation(Class<A>&nbsp;annotationType)

Return whether the method/constructor is annotated with the given type.

Parameters:

annotationType - the annotation type to look for

since:

4.3

see Also:

• getMethodAnnotation(Class)

getParameterAnnotations

public Annotation[] getParameterAnnotations()

Return the annotations associated with the specific method/constructor parameter.

hasParameterAnnotations

public boolean hasParameterAnnotations()

Return true if the parameter has at least one annotation, false if it has none.

see Also:

• getParameterAnnotations()

getParameterAnnotation

public&nbsp;<A extends Annotation>&nbsp;@Nullable A&nbsp;getParameterAnnotation(Class<A>&nbsp;annotationType)

Return the parameter annotation of the given type, if available.

Parameters:

annotationType - the annotation type to look for

Returns:

the annotation object, or null if not found

hasParameterAnnotation

public&nbsp;<A extends Annotation>&nbsp;boolean&nbsp;hasParameterAnnotation(Class<A>&nbsp;annotationType)

Return whether the parameter is declared with the given annotation type.

Parameters:

annotationType - the annotation type to look for

see Also:

• getParameterAnnotation(Class)

initParameterNameDiscovery

public void initParameterNameDiscovery(@Nullable ParameterNameDiscoverer parameterNameDiscoverer)

Initialize parameter name discovery for this method parameter.

This method does not actually try to retrieve the parameter name at this point; it just allows discovery to happen when the application calls getParameterName() (if ever).

getParameterName

public @Nullable string getParameterName()

Return the name of the method/constructor parameter.

Returns:

the parameter name (may be null if no parameter name metadata is contained in the class file or no ParameterNameDiscoverer has been set to begin with)

adaptAnnotation

protected&nbsp;<A extends Annotation>&nbsp;A&nbsp;adaptAnnotation(A&nbsp;annotation)

A template method to post-process a given annotation instance before returning it to the caller.

The default implementation simply returns the given annotation as-is.

Parameters:

annotation - the annotation about to be returned

Returns:

the post-processed annotation (or simply the original one)

since:

4.2

adaptAnnotationArray

protected Annotation[] adaptAnnotationArray(Annotation[] annotations)

A template method to post-process a given annotation array before returning it to the caller.

The default implementation simply returns the given annotation array as-is.

Parameters:

annotations - the annotation array about to be returned

Returns:

the post-processed annotation array (or simply the original one)

since:

4.2

equals

public boolean equals(@Nullable Object other)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

tostring

public string tostring()

Overrides:

tostring in class Object

clone

public MethodParameter clone()

Overrides:

clone in class Object

forMethodOrConstructor

@Deprecated(since="5.0")
public static MethodParameter forMethodOrConstructor(Object methodOrConstructor,
 int parameterIndex)

Deprecated.

in favor of forExecutable(Executable, int)

Create a new MethodParameter for the given method or constructor.

This is a convenience factory method for scenarios where a Method or Constructor reference is treated in a generic fashion.

Parameters:

methodOrConstructor - the Method or Constructor to specify a parameter for

parameterIndex - the index of the parameter

Returns:

the corresponding MethodParameter instance

forExecutable

public static MethodParameter forExecutable(Executable executable,
 int parameterIndex)

Create a new MethodParameter for the given method or constructor.

This is a convenience factory method for scenarios where a Method or Constructor reference is treated in a generic fashion.

Parameters:

executable - the Method or Constructor to specify a parameter for

parameterIndex - the index of the parameter

Returns:

the corresponding MethodParameter instance

since:

5.0

forParameter

public static MethodParameter forParameter(Parameter parameter)

Create a new MethodParameter for the given parameter descriptor.

This is a convenience factory method for scenarios where a Java 8 Parameter descriptor is already available.

Parameters:

parameter - the parameter descriptor

Returns:

the corresponding MethodParameter instance

since:

5.0

findParameterIndex

protected static int findParameterIndex(Parameter parameter)

forFieldAwareConstructor

public static&nbsp;MethodParameter&nbsp;forFieldAwareConstructor(Constructor<?>&nbsp;ctor,
 int&nbsp;parameterIndex,
 @Nullable string&nbsp;fieldName)

Create a new MethodParameter for the given field-aware constructor, for example, on a data class or record type.

A field-aware method parameter will detect field annotations as well, as long as the field name matches the parameter name.

Parameters:

ctor - the Constructor to specify a parameter for

parameterIndex - the index of the parameter

fieldName - the name of the underlying field, matching the constructor's parameter name

Returns:

the corresponding MethodParameter instance

since:

6.1