Interface ClassDesc

All Superinterfaces:
ConstantDesc, TypeDescriptor, TypeDescriptor.OfField<ClassDesc> 
public sealed interface ClassDesc extends ConstantDesc, TypeDescriptor.OfField<ClassDesc>
A nominal descriptor for a Class constant.

For common system types, including all the primitive types, there are predefined ClassDesc constants in ConstantDescs. (The java.lang.constant APIs consider void to be a primitive type.) To create a ClassDesc for a class or interface type, use of(java.lang.String) or ofDescriptor(String); to create a ClassDesc for an array type, use ofDescriptor(String), or first obtain a ClassDesc for the component type and then call the arrayType() or arrayType(int) methods.

Since:
12
See Also:

Nested Class Summary

Nested classes/interfaces declared in interface java.lang.invoke.TypeDescriptor

TypeDescriptor.OfField<F extends TypeDescriptor.OfField<F>>, TypeDescriptor.OfMethod<F extends TypeDescriptor.OfField<F>,M extends TypeDescriptor.OfMethod<F,M>>

Method Summary

Modifier and Type Method Description
default ClassDesc arrayType()
Returns a ClassDesc for an array type whose component type is described by this ClassDesc.
default ClassDesc arrayType(int rank)
Returns a ClassDesc for an array type of the specified rank, whose component type is described by this ClassDesc.
default ClassDesc componentType()
Returns the component type of this ClassDesc, if it describes an array type, or null otherwise.
String descriptorString()
Returns a field type descriptor string for this type
default String displayName()
Returns a human-readable name for the type described by this descriptor.
boolean equals(Object o)
Compare the specified object with this descriptor for equality.
default boolean isArray()
Returns whether this ClassDesc describes an array type.
default boolean isClassOrInterface()
Returns whether this ClassDesc describes a class or interface type.
default boolean isPrimitive()
Returns whether this ClassDesc describes a primitive type.
default ClassDesc nested(String nestedName)
Returns a ClassDesc for a nested class of the class or interface type described by this ClassDesc.
default ClassDesc nested(String firstNestedName, String... moreNestedNames)
Returns a ClassDesc for a nested class of the class or interface type described by this ClassDesc.
static ClassDesc of(String name)
Returns a ClassDesc for a class or interface type, given the name of the class or interface, such as "java.lang.String".
static ClassDesc of(String packageName, String className)
Returns a ClassDesc for a class or interface type, given a package name and the unqualified (simple) name for the class or interface.
static ClassDesc ofDescriptor(String descriptor)
Returns a ClassDesc given a descriptor string for a class, interface, array, or primitive type.
default String packageName()
Returns the package name of this ClassDesc, if it describes a class or interface type.

Methods declared in interface java.lang.constant.ConstantDesc

resolveConstantDesc

Method Details

of

static ClassDesc of(String name)
Returns a ClassDesc for a class or interface type, given the name of the class or interface, such as "java.lang.String". (To create a descriptor for an array type, either use ofDescriptor(String) or arrayType(); to create a descriptor for a primitive type, use ofDescriptor(String) or use the predefined constants in ConstantDescs).
Parameters:
name - the fully qualified (dot-separated) binary class name
Returns:
a ClassDesc describing the desired class
Throws:
NullPointerException - if the argument is null
IllegalArgumentException - if the name string is not in the correct format

of

static ClassDesc of(String packageName, String className)
Returns a ClassDesc for a class or interface type, given a package name and the unqualified (simple) name for the class or interface.
Parameters:
packageName - the package name (dot-separated); if the package name is the empty string, the class is considered to be in the unnamed package
className - the unqualified (simple) class name
Returns:
a ClassDesc describing the desired class
Throws:
NullPointerException - if any argument is null
IllegalArgumentException - if the package name or class name are not in the correct format

ofDescriptor

static ClassDesc ofDescriptor(String descriptor)
Returns a ClassDesc given a descriptor string for a class, interface, array, or primitive type.
API Note:
A field type descriptor string for a non-array type is either a one-letter code corresponding to a primitive type ("J", "I", "C", "S", "B", "D", "F", "Z", "V"), or the letter "L", followed by the fully qualified binary name of a class, followed by ";". A field type descriptor for an array type is the character "[" followed by the field descriptor for the component type. Examples of valid type descriptor strings include "Ljava/lang/String;", "I", "[I", "V", "[Ljava/lang/String;", etc. See JVMS 4.3.2 ("Field Descriptors") for more detail.
Parameters:
descriptor - a field descriptor string
Returns:
a ClassDesc describing the desired class
Throws:
NullPointerException - if the argument is null
IllegalArgumentException - if the name string is not in the correct format
See Java Virtual Machine Specification:
4.3.2 Field Descriptors
4.4.1 The CONSTANT_Class_info Structure

arrayType

default ClassDesc arrayType()
Returns a ClassDesc for an array type whose component type is described by this ClassDesc.
Specified by:
arrayType in interface TypeDescriptor.OfField<ClassDesc>
Returns:
a ClassDesc describing the array type
Throws:
IllegalStateException - if the resulting ClassDesc would have an array rank of greater than 255
See Java Virtual Machine Specification:
4.4.1 The CONSTANT_Class_info Structure

arrayType

default ClassDesc arrayType(int rank)
Returns a ClassDesc for an array type of the specified rank, whose component type is described by this ClassDesc.
Parameters:
rank - the rank of the array
Returns:
a ClassDesc describing the array type
Throws:
IllegalArgumentException - if the rank is less than or equal to zero or if the rank of the resulting array type is greater than 255
See Java Virtual Machine Specification:
4.4.1 The CONSTANT_Class_info Structure

nested

default ClassDesc nested(String nestedName)
Returns a ClassDesc for a nested class of the class or interface type described by this ClassDesc.
API Note:
Example: If descriptor d describes the class java.util.Map, a descriptor for the class java.util.Map.Entry could be obtained by d.nested("Entry").
Parameters:
nestedName - the unqualified name of the nested class
Returns:
a ClassDesc describing the nested class
Throws:
NullPointerException - if the argument is null
IllegalStateException - if this ClassDesc does not describe a class or interface type
IllegalArgumentException - if the nested class name is invalid

nested

default ClassDesc nested(String firstNestedName, String... moreNestedNames)
Returns a ClassDesc for a nested class of the class or interface type described by this ClassDesc.
Parameters:
firstNestedName - the unqualified name of the first level of nested class
moreNestedNames - the unqualified name(s) of the remaining levels of nested class
Returns:
a ClassDesc describing the nested class
Throws:
NullPointerException - if any argument or its contents is null
IllegalStateException - if this ClassDesc does not describe a class or interface type
IllegalArgumentException - if the nested class name is invalid

isArray

default boolean isArray()
Returns whether this ClassDesc describes an array type.
Specified by:
isArray in interface TypeDescriptor.OfField<ClassDesc>
Returns:
whether this ClassDesc describes an array type

isPrimitive

default boolean isPrimitive()
Returns whether this ClassDesc describes a primitive type.
Specified by:
isPrimitive in interface TypeDescriptor.OfField<ClassDesc>
Returns:
whether this ClassDesc describes a primitive type

isClassOrInterface

default boolean isClassOrInterface()
Returns whether this ClassDesc describes a class or interface type.
Returns:
whether this ClassDesc describes a class or interface type

componentType

default ClassDesc componentType()
Returns the component type of this ClassDesc, if it describes an array type, or null otherwise.
Specified by:
componentType in interface TypeDescriptor.OfField<ClassDesc>
Returns:
a ClassDesc describing the component type, or null if this descriptor does not describe an array type

packageName

default String packageName()
Returns the package name of this ClassDesc, if it describes a class or interface type.
Returns:
the package name, or the empty string if the class is in the default package, or this ClassDesc does not describe a class or interface type

displayName

default String displayName()
Returns a human-readable name for the type described by this descriptor.
Implementation Requirements:

The default implementation returns the simple name (e.g., int) for primitive types, the unqualified class name for class or interface types, or the display name of the component type suffixed with the appropriate number of [] pairs for array types.

Returns:
the human-readable name

descriptorString

String descriptorString()
Returns a field type descriptor string for this type
Specified by:
descriptorString in interface TypeDescriptor
Returns:
the descriptor string
See Java Virtual Machine Specification:
4.3.2 Field Descriptors

equals

boolean equals(Object o)
Compare the specified object with this descriptor for equality. Returns true if and only if the specified object is also a ClassDesc and both describe the same type.
Overrides:
equals in class Object
Parameters:
o - the other object
Returns:
whether this descriptor is equal to the other object
See Also:

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https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/constant/ClassDesc.html