Module java.base

Package java.lang.constant

Interface MethodHandleDesc

All Superinterfaces:

ConstantDesc

All Known Subinterfaces:

DirectMethodHandleDesc

public sealed interface MethodHandleDesc
extends ConstantDesc
permits DirectMethodHandleDesc (not exhaustive)

A nominal descriptor for a MethodHandle constant.

Sealed Class Hierarchy Graph:

Since:

12

Method Summary

Modifier and Type	Method	Description
default MethodHandleDesc	asType(MethodTypeDesc type)	Returns a MethodHandleDesc that describes this method handle adapted to a different type, as if by MethodHandle.asType(MethodType).
boolean	equals(Object o)	Compares the specified object with this descriptor for equality.
MethodTypeDesc	invocationType()	Returns a MethodTypeDesc describing the invocation type of the method handle described by this nominal descriptor.
static DirectMethodHandleDesc	of(DirectMethodHandleDesc.Kind kind, ClassDesc owner, String name, String lookupDescriptor)	Creates a MethodHandleDesc corresponding to an invocation of a declared method, invocation of a constructor, or access to a field.
static DirectMethodHandleDesc	ofConstructor(ClassDesc owner, ClassDesc... paramTypes)	Returns a MethodHandleDesc corresponding to invocation of a constructor
static DirectMethodHandleDesc	ofField(DirectMethodHandleDesc.Kind kind, ClassDesc owner, String fieldName, ClassDesc fieldType)	Creates a MethodHandleDesc corresponding to a method handle that accesses a field.
static DirectMethodHandleDesc	ofMethod(DirectMethodHandleDesc.Kind kind, ClassDesc owner, String name, MethodTypeDesc lookupMethodType)	Creates a MethodHandleDesc corresponding to an invocation of a declared method or constructor.
MethodHandle	resolveConstantDesc(MethodHandles.Lookup lookup)	Resolves this descriptor reflectively, emulating the resolution behavior of JVMS 5.4.3 and the access control behavior of JVMS 5.4.4.

Method Details

of

static DirectMethodHandleDesc of(DirectMethodHandleDesc.Kind kind,
 ClassDesc owner,
 String name,
 String lookupDescriptor)

Creates a MethodHandleDesc corresponding to an invocation of a declared method, invocation of a constructor, or access to a field.

The lookup descriptor string has the same format as for the various variants of CONSTANT_MethodHandle_info and for the lookup methods on MethodHandles.Lookup. For a method or constructor invocation, it is interpreted as a method type descriptor; for field access, it is interpreted as a field descriptor. If kind is CONSTRUCTOR, the name parameter is ignored and the return type of the lookup descriptor must be void. If kind corresponds to a virtual method invocation, the lookup type includes the method parameters but not the receiver type.

Parameters:

kind - The kind of method handle to be described

owner - a ClassDesc describing the class containing the method, constructor, or field

name - the unqualified name of the method or field (ignored if kind is CONSTRUCTOR)

lookupDescriptor - a method descriptor string the lookup type, if the request is for a method invocation, or describing the invocation type, if the request is for a field or constructor

Returns:

the MethodHandleDesc

Throws:

NullPointerException - if any of the non-ignored arguments are null

IllegalArgumentException - if the descriptor string is not a valid method or field descriptor

See Java Virtual Machine Specification:

4.4.8 The CONSTANT_MethodHandle_info Structure
4.2.2 Unqualified Names
4.3.2 Field Descriptors
4.3.3 Method Descriptors

ofMethod

static DirectMethodHandleDesc ofMethod(DirectMethodHandleDesc.Kind kind,
 ClassDesc owner,
 String name,
 MethodTypeDesc lookupMethodType)

Creates a MethodHandleDesc corresponding to an invocation of a declared method or constructor.

The lookup descriptor string has the same format as for the lookup methods on MethodHandles.Lookup. If kind is CONSTRUCTOR, the name is ignored and the return type of the lookup type must be void. If kind corresponds to a virtual method invocation, the lookup type includes the method parameters but not the receiver type.

Parameters:

kind - The kind of method handle to be described; must be one of SPECIAL, VIRTUAL, STATIC, INTERFACE_SPECIAL, INTERFACE_VIRTUAL, INTERFACE_STATIC, CONSTRUCTOR

owner - a ClassDesc describing the class containing the method or constructor

name - the unqualified name of the method (ignored if kind is CONSTRUCTOR)

lookupMethodType - a MethodTypeDesc describing the lookup type

Returns:

the MethodHandleDesc

Throws:

NullPointerException - if any non-ignored arguments are null

IllegalArgumentException - if the name has the incorrect format, or the kind is invalid

See Java Virtual Machine Specification:

4.2.2 Unqualified Names

ofField

static DirectMethodHandleDesc ofField(DirectMethodHandleDesc.Kind kind,
 ClassDesc owner,
 String fieldName,
 ClassDesc fieldType)

Creates a MethodHandleDesc corresponding to a method handle that accesses a field.

Parameters:

kind - the kind of the method handle to be described; must be one of GETTER, SETTER, STATIC_GETTER, or STATIC_SETTER

owner - a ClassDesc describing the class containing the field

fieldName - the unqualified name of the field

fieldType - a ClassDesc describing the type of the field

Returns:

the MethodHandleDesc

Throws:

NullPointerException - if any of the arguments are null

IllegalArgumentException - if the kind is not one of the valid values or if the field name is not valid

See Java Virtual Machine Specification:

4.2.2 Unqualified Names

ofConstructor

static DirectMethodHandleDesc ofConstructor(ClassDesc owner,
 ClassDesc... paramTypes)

Returns a MethodHandleDesc corresponding to invocation of a constructor

Parameters:

owner - a ClassDesc describing the class containing the constructor

paramTypes - ClassDescs describing the parameter types of the constructor

Returns:

the MethodHandleDesc

Throws:

NullPointerException - if any argument or its contents is null

asType

default MethodHandleDesc asType(MethodTypeDesc type)

Returns a MethodHandleDesc that describes this method handle adapted to a different type, as if by MethodHandle.asType(MethodType).

Parameters:

type - a MethodHandleDesc describing the new method type

Returns:

a MethodHandleDesc for the adapted method handle

Throws:

NullPointerException - if the argument is null

invocationType

MethodTypeDesc invocationType()

Returns a MethodTypeDesc describing the invocation type of the method handle described by this nominal descriptor. The invocation type describes the full set of stack values that are consumed by the invocation (including the receiver, if any).

Returns:

a MethodHandleDesc describing the method handle type

resolveConstantDesc

MethodHandle resolveConstantDesc(MethodHandles.Lookup lookup)
                          throws ReflectiveOperationException

Description copied from interface: ConstantDesc

Resolves this descriptor reflectively, emulating the resolution behavior of JVMS 5.4.3 and the access control behavior of JVMS 5.4.4. The resolution and access control context is provided by the MethodHandles.Lookup parameter. No caching of the resulting value is performed.

Specified by:

resolveConstantDesc in interface ConstantDesc

Parameters:

lookup - The MethodHandles.Lookup to provide name resolution and access control context

Returns:

the resolved constant value

Throws:

ReflectiveOperationException - if a class, method, or field could not be reflectively resolved in the course of resolution

equals

boolean equals(Object o)

Compares the specified object with this descriptor for equality. Returns true if and only if the specified object is also a MethodHandleDesc, and both encode the same nominal description of a method handle.

Overrides:

equals in class Object

Parameters:

o - the other object

Returns:

whether this descriptor is equal to the other object

See Also:

• Object.hashCode()
• HashMap