Module java.compiler

Package javax.lang.model.util

Interface Elements

public interface Elements

Utility methods for operating on program elements.

Compatibility Note: Methods may be added to this interface in future releases of the platform.

Since:

1.6

See Also:

• ProcessingEnvironment.getElementUtils()

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static enum	Elements.Origin	The origin of an element or other language model item.

Method Summary

Modifier and Type	Method	Description
List<? extends AnnotationMirror>	getAllAnnotationMirrors(Element e)	Returns all annotations present on an element, whether directly present or present via inheritance.
List<? extends Element>	getAllMembers(TypeElement type)	Returns all members of a type element, whether inherited or declared directly.
default Set<? extends ModuleElement>	getAllModuleElements()	Returns all module elements in the current environment.
default Set<? extends PackageElement>	getAllPackageElements(CharSequence name)	Returns all package elements with the given canonical name.
default Set<? extends TypeElement>	getAllTypeElements(CharSequence name)	Returns all type elements with the given canonical name.
Name	getBinaryName(TypeElement type)	Returns the binary name of a type element.
String	getConstantExpression(Object value)	Returns the text of a constant expression representing a primitive value or a string.
String	getDocComment(Element e)	Returns the text of the documentation ("Javadoc") comment of an element.
Map<? extends ExecutableElement,? extends AnnotationValue>	getElementValuesWithDefaults(AnnotationMirror a)	Returns the values of an annotation's elements, including defaults.
default TypeElement	getEnumConstantBody(VariableElement enumConstant)	Returns the class body of an enum constant if the argument is an enum constant declared with an optional class body, null otherwise.
default JavaFileObject	getFileObjectOf(Element e)	Returns the file object for this element or null if there is no such file object.
default ModuleElement	getModuleElement(CharSequence name)	Returns a module element given its fully qualified name.
default ModuleElement	getModuleOf(Element e)	Returns the module of an element.
Name	getName(CharSequence cs)	Returns a name with the same sequence of characters as the argument.
default Elements.Origin	getOrigin(AnnotatedConstruct c, AnnotationMirror a)	Returns the origin of the given annotation mirror.
default Elements.Origin	getOrigin(Element e)	Returns the origin of the given element.
default Elements.Origin	getOrigin(ModuleElement m, ModuleElement.Directive directive)	Returns the origin of the given module directive.
default TypeElement	getOutermostTypeElement(Element e)	Returns the outermost type element an element is contained in if such a containing element exists; otherwise returns null.
PackageElement	getPackageElement(CharSequence name)	Returns a package given its fully qualified name if the package is uniquely determinable in the environment.
default PackageElement	getPackageElement(ModuleElement module, CharSequence name)	Returns a package given its fully qualified name, as seen from the given module.
PackageElement	getPackageOf(Element e)	Returns the package of an element.
TypeElement	getTypeElement(CharSequence name)	Returns a type element given its canonical name if the type element is uniquely determinable in the environment.
default TypeElement	getTypeElement(ModuleElement module, CharSequence name)	Returns a type element given its canonical name, as seen from the given module.
boolean	hides(Element hider, Element hidden)	Tests whether one type, method, or field hides another.
default boolean	isAutomaticModule(ModuleElement module)	Returns true if the module element is an automatic module, false otherwise.
default boolean	isBridge(ExecutableElement e)	Returns true if the executable element is a bridge method, false otherwise.
default boolean	isCanonicalConstructor(ExecutableElement e)	Returns true if the executable element can be determined to be a canonical constructor of a record, false otherwise.
default boolean	isCompactConstructor(ExecutableElement e)	Returns true if the executable element can be determined to be a compact constructor of a record, false otherwise.
boolean	isDeprecated(Element e)	Returns true if the element is deprecated, false otherwise.
boolean	isFunctionalInterface(TypeElement type)	Returns true if the type element is a functional interface, false otherwise.
boolean	overrides(ExecutableElement overrider, ExecutableElement overridden, TypeElement type)	Tests whether one method, as a member of a given class or interface, overrides another method.
void	printElements(Writer w, Element... elements)	Prints a representation of the elements to the given writer in the specified order.
default RecordComponentElement	recordComponentFor(ExecutableElement accessor)	Returns the record component for the given accessor.

Method Details

getPackageElement

PackageElement getPackageElement(CharSequence name)

Returns a package given its fully qualified name if the package is uniquely determinable in the environment. If running with modules, packages of the given name are searched in a two-stage process:

• find non-empty packages with the given name returned by getPackageElement(ModuleElement, CharSequence), where the provided ModuleSymbol is any root module,
• if the above yields an empty list, search all modules for observable packages with the given name

If this process leads to a list with a single element, the single element is returned, otherwise null is returned.

Parameters:

name - fully qualified package name, or an empty string for an unnamed package

Returns:

the specified package, or null if no package can be uniquely determined.

getPackageElement

default PackageElement getPackageElement(ModuleElement module,
 CharSequence name)

Returns a package given its fully qualified name, as seen from the given module.

Implementation Requirements:

The default implementation of this method returns null.

Parameters:

module - module relative to which the lookup should happen

name - fully qualified package name, or an empty string for an unnamed package

Returns:

the specified package, or null if it cannot be found

Since:

9

See Also:

• getAllPackageElements(java.lang.CharSequence)

getAllPackageElements

default Set<? extends PackageElement> getAllPackageElements(CharSequence name)

Returns all package elements with the given canonical name. There may be more than one package element with the same canonical name if the package elements are in different modules.

Implementation Requirements:

The default implementation of this method calls getAllModuleElements and stores the result. If the set of modules is empty, getPackageElement(name) is called passing through the name argument. If getPackageElement(name) is null, an empty set of package elements is returned; otherwise, a single-element set with the found package element is returned. If the set of modules is nonempty, the modules are iterated over and any non-null results of getPackageElement(module, name) are accumulated into a set. The set is then returned.

Parameters:

name - the canonical name

Returns:

the package elements, or an empty set if no package with the name can be found

Since:

9

See Also:

• getPackageElement(ModuleElement, CharSequence)

getTypeElement

TypeElement getTypeElement(CharSequence name)

Returns a type element given its canonical name if the type element is uniquely determinable in the environment. If running with modules, type elements of the given name are searched in a two-stage process:

• find type elements with the given name returned by getTypeElement(ModuleElement, CharSequence), where the provided ModuleSymbol is any root module,
• if the above yields an empty list, search all modules for observable type elements with the given name

If this process leads to a list with a single element, the single element is returned, otherwise null is returned.

Parameters:

name - the canonical name

Returns:

the named type element, or null if no type element can be uniquely determined.

getTypeElement

default TypeElement getTypeElement(ModuleElement module,
 CharSequence name)

Returns a type element given its canonical name, as seen from the given module.

Implementation Requirements:

The default implementation of this method returns null.

Parameters:

module - module relative to which the lookup should happen

name - the canonical name

Returns:

the named type element, or null if it cannot be found

Since:

9

See Also:

• getAllTypeElements(java.lang.CharSequence)

getAllTypeElements

default Set<? extends TypeElement> getAllTypeElements(CharSequence name)

Returns all type elements with the given canonical name. There may be more than one type element with the same canonical name if the type elements are in different modules.

Implementation Requirements:

The default implementation of this method calls getAllModuleElements and stores the result. If the set of modules is empty, getTypeElement(name) is called passing through the name argument. If getTypeElement(name) is null, an empty set of type elements is returned; otherwise, a single-element set with the found type element is returned. If the set of modules is nonempty, the modules are iterated over and any non-null results of getTypeElement(module, name) are accumulated into a set. The set is then returned.

Parameters:

name - the canonical name

Returns:

the type elements, or an empty set if no type with the name can be found

Since:

9

See Also:

• getTypeElement(ModuleElement, CharSequence)

getModuleElement

default ModuleElement getModuleElement(CharSequence name)

Returns a module element given its fully qualified name. If the requested module cannot be found, null is returned. One situation where a module cannot be found is if the environment does not include modules, such as an annotation processing environment configured for a source version without modules.

Implementation Requirements:

The default implementation of this method returns null.

Parameters:

name - the name, or an empty string for an unnamed module

Returns:

the named module element, or null if it cannot be found

Since:

9

See Also:

• getAllModuleElements()

getAllModuleElements

default Set<? extends ModuleElement> getAllModuleElements()

Returns all module elements in the current environment. If no modules are present, an empty set is returned. One situation where no modules are present occurs when the environment does not include modules, such as an annotation processing environment configured for a source version without modules.

API Note:

When an environment includes modules, both named modules and unnamed modules may be returned.

Implementation Requirements:

The default implementation of this method returns an empty set.

Returns:

the known module elements, or an empty set if there are no modules

Since:

9

See Also:

• getModuleElement(CharSequence)

getElementValuesWithDefaults

Map<? extends ExecutableElement,? extends AnnotationValue> getElementValuesWithDefaults(AnnotationMirror a)

Returns the values of an annotation's elements, including defaults.

Parameters:

a - annotation to examine

Returns:

the values of an annotation's elements, including defaults

See Also:

• AnnotationMirror.getElementValues()

getDocComment

String getDocComment(Element e)

Returns the text of the documentation ("Javadoc") comment of an element.

A documentation comment of an element is a comment that begins with "/**", ends with a separate "*/", and immediately precedes the element, ignoring white space, annotations, end-of-line-comments ( "//" comments), and intermediate traditional comments ("/* ... */" comments) that are not doc comments. Therefore, a documentation comment contains at least three "*" characters. The text returned for the documentation comment is a processed form of the comment as it appears in source code:

• The leading "/**" is removed, as are any immediately following space characters on that line. If all the characters of the line are removed, it makes no contribution to the returned comment.
• For subsequent lines of the doc comment starting after the initial "/**", if the lines start with zero or more whitespace characters followed by one or more "*" characters, those leading whitespace characters are discarded as are any consecutive "*" characters appearing after the white space or starting the line. Otherwise, if a line does not have a prefix of the described form, the entire line is retained.
• The trailing "*/" is removed. The line with the trailing" */" also undergoes leading space and "*" character removal as described above. If all the characters of the line are removed, it makes no contribution to the returned comment.

The processed lines are then concatenated together (including line terminators) and returned.

Parameters:

e - the element being examined

Returns:

the documentation comment of the element, or null if there is none

See Java Language Specification:

3.6 White Space
3.7 Comments

isDeprecated

boolean isDeprecated(Element e)

Returns true if the element is deprecated, false otherwise.

Parameters:

e - the element being examined

Returns:

true if the element is deprecated, false otherwise

getOrigin

default Elements.Origin getOrigin(Element e)

Returns the origin of the given element.

Note that if this method returns EXPLICIT and the element was created from a class file, then the element may not, in fact, correspond to an explicitly declared construct in source code. This is due to limitations of the fidelity of the class file format in preserving information from source code. For example, at least some versions of the class file format do not preserve whether a constructor was explicitly declared by the programmer or was implicitly declared as the default constructor.

Implementation Requirements:

The default implementation of this method returns EXPLICIT.

Parameters:

e - the element being examined

Returns:

the origin of the given element

Since:

9

getOrigin

default Elements.Origin getOrigin(AnnotatedConstruct c,
 AnnotationMirror a)

Returns the origin of the given annotation mirror. An annotation mirror is mandated if it is an implicitly declared container annotation used to hold repeated annotations of a repeatable annotation interface.

Note that if this method returns EXPLICIT and the annotation mirror was created from a class file, then the element may not, in fact, correspond to an explicitly declared construct in source code. This is due to limitations of the fidelity of the class file format in preserving information from source code. For example, at least some versions of the class file format do not preserve whether an annotation was explicitly declared by the programmer or was implicitly declared as a container annotation.

Implementation Requirements:

The default implementation of this method returns EXPLICIT.

Parameters:

c - the construct the annotation mirror modifies

a - the annotation mirror being examined

Returns:

the origin of the given annotation mirror

See Java Language Specification:

9.6.3 Repeatable Annotation Interfaces
9.7.5 Multiple Annotations of the Same Interface

Since:

9

getOrigin

default Elements.Origin getOrigin(ModuleElement m,
 ModuleElement.Directive directive)

Returns the origin of the given module directive.

Note that if this method returns EXPLICIT and the module directive was created from a class file, then the module directive may not, in fact, correspond to an explicitly declared construct in source code. This is due to limitations of the fidelity of the class file format in preserving information from source code. For example, at least some versions of the class file format do not preserve whether a uses directive was explicitly declared by the programmer or was added as a synthetic construct.

Note that an implementation may not be able to reliably determine the origin status of the directive if the directive is created from a class file due to limitations of the fidelity of the class file format in preserving information from source code.

Implementation Requirements:

The default implementation of this method returns EXPLICIT.

Parameters:

m - the module of the directive

directive - the module directive being examined

Returns:

the origin of the given module directive

Since:

9

isBridge

default boolean isBridge(ExecutableElement e)

Returns true if the executable element is a bridge method, false otherwise.

Implementation Requirements:

The default implementation of this method returns false.

Parameters:

e - the executable being examined

Returns:

true if the executable element is a bridge method, false otherwise

Since:

9

getBinaryName

Name getBinaryName(TypeElement type)

Returns the binary name of a type element.

Parameters:

type - the type element being examined

Returns:

the binary name of a type element

See Java Language Specification:

13.1 The Form of a Binary

See Also:

• TypeElement.getQualifiedName()

getPackageOf

PackageElement getPackageOf(Element e)

Returns the package of an element. The package of a package is itself. The package of a module is null. The package of a top-level class or interface is its enclosing package. Otherwise, the package of an element is equal to the package of the enclosing element.

Parameters:

e - the element being examined

Returns:

the package of an element

getModuleOf

default ModuleElement getModuleOf(Element e)

Returns the module of an element. The module of a module is itself. If a package has a module as its enclosing element, that module is the module of the package. If the enclosing element of a package is null, null is returned for the package's module. (One situation where a package may have a null module is if the environment does not include modules, such as an annotation processing environment configured for a source version without modules.) Otherwise, the module of an element is equal to the module of the package of the element.

Implementation Requirements:

The default implementation of this method returns null.

Parameters:

e - the element being examined

Returns:

the module of an element

Since:

9

getAllMembers

List<? extends Element> getAllMembers(TypeElement type)

Returns all members of a type element, whether inherited or declared directly. For a class the result also includes its constructors, but not local or anonymous classes.

API Note:

Elements of certain kinds can be isolated using methods in ElementFilter.

Parameters:

type - the type being examined

Returns:

all members of the type

See Also:

• Element.getEnclosedElements()

getOutermostTypeElement

default TypeElement getOutermostTypeElement(Element e)

Returns the outermost type element an element is contained in if such a containing element exists; otherwise returns null. Modules and packages do not have a containing type element and therefore null is returned for those kinds of elements. A top-level class or interface is its own outermost type element.

Implementation Requirements:

The default implementation of this method first checks the kind of the argument. For elements of kind PACKAGE, MODULE, and OTHER, null is returned. For elements of other kinds, the element is examined to see if it is a top-level class or interface. If so, that element is returned; otherwise, the enclosing element chain is followed until a top-level class or interface is found. The element for the eventual top-level class or interface is returned.

Parameters:

e - the element being examined

Returns:

the outermost type element an element is contained in if such a containing element exists; otherwise returns null

Since:

18

See Also:

• Element.getEnclosingElement()

getAllAnnotationMirrors

List<? extends AnnotationMirror> getAllAnnotationMirrors(Element e)

Returns all annotations present on an element, whether directly present or present via inheritance.

Note that any annotations returned by this method are declaration annotations.

Parameters:

e - the element being examined

Returns:

all annotations of the element

See Also:

• Element.getAnnotationMirrors()
• AnnotatedConstruct

hides

boolean hides(Element hider,
 Element hidden)

Tests whether one type, method, or field hides another.

Parameters:

hider - the first element

hidden - the second element

Returns:

true if and only if the first element hides the second

See Java Language Specification:

8.4.8 Inheritance, Overriding, and Hiding

overrides

boolean overrides(ExecutableElement overrider,
 ExecutableElement overridden,
 TypeElement type)

Tests whether one method, as a member of a given class or interface, overrides another method. When a non-abstract method overrides an abstract one, the former is also said to implement the latter. As implied by JLS 8.4.8.1, a method does not override itself. The overrides relation is irreflexive.

In the simplest and most typical usage, the value of the type parameter will simply be the class or interface directly enclosing overrider (the possibly-overriding method). For example, suppose m1 represents the method String.hashCode and m2 represents Object.hashCode. We can then ask whether m1 overrides m2 within the class String (it does):

assert elements.overrides(m1, m2, elements.getTypeElement("java.lang.String"));

A more interesting case can be illustrated by the following example in which a method in class A does not override a like-named method in interface B:

class A { public void m() {} }
interface B { void m(); }
...
m1 = ...; // A.m
m2 = ...; // B.m
assert ! elements.overrides(m1, m2, elements.getTypeElement("A"));

When viewed as a member of a third class C, however, the method in A does override the one in B:

class C extends A implements B {}
...
assert elements.overrides(m1, m2, elements.getTypeElement("C"));

Parameters:

overrider - the first method, possible overrider

overridden - the second method, possibly being overridden

type - the class or interface of which the first method is a member

Returns:

true if and only if the first method overrides the second

See Java Language Specification:

8.4.8 Inheritance, Overriding, and Hiding
9.4.1 Inheritance and Overriding

getConstantExpression

String getConstantExpression(Object value)

Returns the text of a constant expression representing a primitive value or a string. The text returned is in a form suitable for representing the value in source code.

Parameters:

value - a primitive value or string

Returns:

the text of a constant expression

Throws:

IllegalArgumentException - if the argument is not a primitive value or string

See Also:

• VariableElement.getConstantValue()

printElements

void printElements(Writer w,
 Element... elements)

Prints a representation of the elements to the given writer in the specified order. The main purpose of this method is for diagnostics. The exact format of the output is not specified and is subject to change.

Parameters:

w - the writer to print the output to

elements - the elements to print

getName

Name getName(CharSequence cs)

Returns a name with the same sequence of characters as the argument.

Parameters:

cs - the character sequence to return as a name

Returns:

a name with the same sequence of characters as the argument

isFunctionalInterface

boolean isFunctionalInterface(TypeElement type)

Returns true if the type element is a functional interface, false otherwise.

Parameters:

type - the type element being examined

Returns:

true if the type element is a functional interface, false otherwise

See Java Language Specification:

9.8 Functional Interfaces

Since:

1.8

isAutomaticModule

default boolean isAutomaticModule(ModuleElement module)

Returns true if the module element is an automatic module, false otherwise.

Implementation Requirements:

The default implementation of this method returns false.

Parameters:

module - the module element being examined

Returns:

true if the module element is an automatic module, false otherwise

See Java Language Specification:

7.7.1 Dependences

Since:

17

getEnumConstantBody

default TypeElement getEnumConstantBody(VariableElement enumConstant)

Returns the class body of an enum constant if the argument is an enum constant declared with an optional class body, null otherwise.

Implementation Requirements:

The default implementation of this method throws UnsupportedOperationException if the argument is an enum constant and throws an IllegalArgumentException if it is not.

Parameters:

enumConstant - an enum constant

Returns:

the class body of an enum constant if the argument is an enum constant declared with an optional class body, null otherwise

Throws:

IllegalArgumentException - if the argument is not an enum constant

See Java Language Specification:

8.9.1 Enum Constants

Since:

22

recordComponentFor

default RecordComponentElement recordComponentFor(ExecutableElement accessor)

Returns the record component for the given accessor. Returns null if the given method is not a record component accessor.

Implementation Requirements:

The default implementation of this method checks if the element enclosing the accessor has kind RECORD if that is the case, then all the record components on the accessor's enclosing element are retrieved by invoking ElementFilter.recordComponentsIn(Iterable). If the accessor of at least one of the record components retrieved happen to be equal to the accessor passed as a parameter to this method, then that record component is returned, in any other case null is returned.

Parameters:

accessor - the method for which the record component should be found.

Returns:

the record component, or null if the given method is not a record component accessor

Since:

16

isCanonicalConstructor

default boolean isCanonicalConstructor(ExecutableElement e)

Returns true if the executable element can be determined to be a canonical constructor of a record, false otherwise. Note that in some cases there may be insufficient information to determine if a constructor is a canonical constructor, such as if the executable element is built backed by a class file. In such cases, false is returned.

Implementation Requirements:

The default implementation of this method unconditionally returns false.

Parameters:

e - the executable being examined

Returns:

true if the executable element can be determined to be a canonical constructor of a record, false otherwise

See Java Language Specification:

8.10.4.1 Normal Canonical Constructors

Since:

20

isCompactConstructor

default boolean isCompactConstructor(ExecutableElement e)

Returns true if the executable element can be determined to be a compact constructor of a record, false otherwise. By definition, a compact constructor is also a canonical constructor. Note that in some cases there may be insufficient information to determine if a constructor is a compact constructor, such as if the executable element is built backed by a class file. In such cases, false is returned.

Implementation Requirements:

The default implementation of this method unconditionally returns false.

Parameters:

e - the executable being examined

Returns:

true if the executable element can be determined to be a compact constructor of a record, false otherwise

See Java Language Specification:

8.10.4.2 Compact Canonical Constructors

Since:

20

getFileObjectOf

default JavaFileObject getFileObjectOf(Element e)

Returns the file object for this element or null if there is no such file object.

The returned file object is for the reference representation of the information used to construct the element. For example, if during compilation or annotation processing, a source file for class Foo is compiled into a class file, the file object returned for the element representing Foo would be for the source file and not for the class file.

An implementation may choose to not support the functionality of this method, in which case UnsupportedOperationException is thrown.

In the context of annotation processing, a non-null value is returned if the element was included as part of the initial inputs or the containing file was created during the run of the annotation processing tool. Otherwise, a null may be returned. In annotation processing, if a class file is created, that class file can serve as the reference representation for elements.

If it has a file object, the file object for a package will be a package-info file. A package may exist and not have any package-info file even if the package is (implicitly) created during an annotation processing run from the creation of source or class files in that package. An unnamed package will have a null file since it cannot be declared in a compilation unit.

If it has a file object, the file object for a module will be a module-info file. An unnamed module will have a null file since it cannot be declared in a compilation unit. An automatic module will have a null file since it is implicitly declared.

If it has a file object, the file object for a top-level public class or interface will be a source or class file corresponding to that class or interface. In this case, typically the leading portion of the name of the file will match the name of the class or interface. A single compilation unit can define multiple top-level classes and interfaces, such as a primary public class or interfaces whose name corresponds to the file name and one or more auxiliary classes or interfaces whose names do not correspond to the file name. If a source file is providing the reference representation of an auxiliary class or interface, the file for the primary class is returned. (An auxiliary class or interface can also be defined in a package-info source file, in which case the file for the package-info file is returned.) If a class file is providing the reference representation of an auxiliary class or interface, the separate class file for the auxiliary class is returned.

For a nested class or interface, if it has a file object:

• if a source file is providing the reference representation, the file object will be that of the outermost enclosing class or interface
• if a class file is providing the reference representation, the file object will be that of the nested class or interface itself

For other lexically enclosed elements, such as variables, methods, and constructors, if they have a file object, the file object will be the object associated with the enclosing element of the lexically enclosed element.

Implementation Requirements:

The default implementation unconditionally throws UnsupportedOperationException.

Parameters:

e - the element to find a file object for

Returns:

the file object for this element or null if there is no such file object

Throws:

UnsupportedOperationException - if this functionality is not supported

Since:

18