Compatibility Note: Methods may be added to this interface * in future releases of the platform. * * @see javax.annotation.processing.ProcessingEnvironment#getElementUtils * @since 1.6 */ public interface Elements { /** * 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: *
A documentation comment of an element is a particular kind * of comment that immediately precedes the element, ignoring * white space, annotations and any other comments that are * not themselves documentation comments. * *
There are two kinds of documentation comments, either based on * traditional comments or based on a series of * end-of-line comments. For both kinds, the text * returned for the documentation comment is a processed form of * the comment as it appears in source code, as described below. * *
A {@linkplain DocCommentKind#TRADITIONAL traditional
* documentation comment} is a traditional comment that begins
* with "{@code /**}", and ends with a separate "*/".
* (Therefore, such a comment contains at least three "{@code *}"
* characters.)
* The lines of such a comment are processed as follows:
*
*/" is removed. The line
* with the trailing" */" also undergoes leading
* space and "{@code *}" character removal as described above.
* An {@linkplain DocCommentKind#END_OF_LINE end-of-line * documentation comment} is a series of adjacent end-of-line * comments, each on a line by itself, ignoring any whitespace * characters at the beginning of the line, and each beginning * with "{@code ///}". * The lines of such a comment are processed as follows: *
Note that if this method returns {@link Origin#EXPLICIT * 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. * * @implSpec The default implementation of this method returns * {@link Origin#EXPLICIT EXPLICIT}. * * @param e the element being examined * @since 9 */ default Origin getOrigin(Element e) { return Origin.EXPLICIT; } /** * {@return the origin of the given annotation mirror} * * An annotation mirror is {@linkplain Origin#MANDATED 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 {@link Origin#EXPLICIT * 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. * * @implSpec The default implementation of this method returns * {@link Origin#EXPLICIT EXPLICIT}. * * @param c the construct the annotation mirror modifies * @param a the annotation mirror being examined * @jls 9.6.3 Repeatable Annotation Interfaces * @jls 9.7.5 Multiple Annotations of the Same Interface * @since 9 */ default Origin getOrigin(AnnotatedConstruct c, AnnotationMirror a) { return Origin.EXPLICIT; } /** * {@return the origin of the given module directive} * *
Note that if this method returns {@link Origin#EXPLICIT * 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 {@code 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. * * @implSpec The default implementation of this method returns * {@link Origin#EXPLICIT EXPLICIT}. * * @param m the module of the directive * @param directive the module directive being examined * @since 9 */ default Origin getOrigin(ModuleElement m, ModuleElement.Directive directive) { return Origin.EXPLICIT; } /** * The origin of an element or other language model * item. The origin of an element or item models how a construct * in a program is declared in the source code, explicitly, * implicitly, etc. * *
Note that it is possible additional kinds of origin values
* will be added in future versions of the platform.
*
* @jls 13.1 The Form of a Binary
* @since 9
*/
public enum Origin {
/**
* Describes a construct explicitly declared in source code.
*/
EXPLICIT,
/**
* A mandated construct is one that is not explicitly declared
* in the source code, but whose presence is mandated by the
* specification. Such a construct is said to be implicitly
* declared.
*
* One example of a mandated element is a default
* constructor in a class that contains no explicit
* constructor declarations.
*
* Another example of a mandated construct is an implicitly
* declared container annotation used to hold
* multiple annotations of a repeatable annotation interface.
*
* @jls 8.8.9 Default Constructor
* @jls 8.9.3 Enum Members
* @jls 8.10.3 Record Members
* @jls 9.6.3 Repeatable Annotation Interfaces
* @jls 9.7.5 Multiple Annotations of the Same Interface
*/
MANDATED,
/**
* A synthetic construct is one that is neither implicitly nor
* explicitly declared in the source code. Such a construct is
* typically a translation artifact created by a compiler.
*/
SYNTHETIC;
/**
* Returns {@code true} for values corresponding to constructs
* that are implicitly or explicitly declared, {@code false}
* otherwise.
* @return {@code true} for {@link #EXPLICIT} and {@link #MANDATED},
* {@code false} otherwise.
*/
public boolean isDeclared() {
return this != SYNTHETIC;
}
}
/**
* {@return {@code true} if the executable element is a bridge
* method, {@code false} otherwise}
*
* @implSpec The default implementation of this method returns {@code false}.
*
* @param e the executable being examined
* @since 9
*/
default boolean isBridge(ExecutableElement e) {
return false;
}
/**
* {@return the binary name of a type element}
*
* @param type the type element being examined
*
* @see TypeElement#getQualifiedName
* @jls 13.1 The Form of a Binary
*/
Name getBinaryName(TypeElement type);
/**
* {@return the package of an element} The package of a package is
* itself.
* The package of a module is {@code null}.
*
* The package of a top-level class or interface is its {@linkplain
* TypeElement#getEnclosingElement enclosing package}. Otherwise,
* the package of an element is equal to the package of the
* {@linkplain Element#getEnclosingElement enclosing element}.
*
* @param e the element being examined
*/
PackageElement getPackageOf(Element e);
/**
* {@return the module of an element} The module of a module is
* itself.
*
* If a package has a module as its {@linkplain
* PackageElement#getEnclosingElement enclosing element}, that
* module is the module of the package. If the enclosing element
* of a package is {@code null}, {@code null} is returned for the
* package's module.
*
* (One situation where a package may have a {@code null} module
* is if the environment does not include modules, such as an
* annotation processing environment configured for a {@linkplain
* javax.annotation.processing.ProcessingEnvironment#getSourceVersion
* source version} without modules.)
*
* Otherwise, the module of an element is equal to the module
* {@linkplain #getPackageOf(Element) of the package} of the
* element.
*
* @implSpec The default implementation of this method returns
* {@code null}.
*
* @param e the element being examined
* @since 9
*/
default ModuleElement getModuleOf(Element e) {
return null;
}
/**
* 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.
*
* @apiNote Elements of certain kinds can be isolated using
* methods in {@link ElementFilter}.
*
* @param type the type being examined
* @return all members of the type
* @see Element#getEnclosedElements
*/
List getAllMembers(TypeElement type);
/**
* {@return the outermost type element an element is contained in
* if such a containing element exists; otherwise returns {@code
* null}}
*
* {@linkplain ModuleElement Modules} and {@linkplain
* PackageElement packages} do not have a containing type
* element and therefore {@code null} is returned for those kinds
* of elements.
*
* A {@linkplain NestingKind#TOP_LEVEL top-level} class or
* interface is its own outermost type element.
*
* @implSpec
* The default implementation of this method first checks the kind
* of the argument. For elements of kind {@code PACKAGE}, {@code
* MODULE}, and {@code OTHER}, {@code 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 {@linkplain
* Element#getEnclosingElement 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.
*
* @param e the element being examined
* @see Element#getEnclosingElement
* @since 18
*/
default TypeElement getOutermostTypeElement(Element e) {
return switch (e.getKind()) {
case PACKAGE,
MODULE -> null; // Per the general spec above.
case OTHER -> null; // Outside of base model of the javax.lang.model API
// Elements of all remaining kinds should be enclosed in some
// sort of class or interface. Check to see if the element is
// a top-level type; if so, return it. Otherwise, keep going
// up the enclosing element chain until a top-level type is
// found.
default -> {
Element enclosing = e;
// This implementation is susceptible to infinite loops
// for misbehaving element implementations.
while (true) {
// Conceptual instanceof TypeElement check. If the
// argument is a type element, put it into a
// one-element list, otherwise an empty list.
List Note that any annotations returned by this method are
* declaration annotations.
*
* @param e the element being examined
* @return all annotations of the element
* @see Element#getAnnotationMirrors
* @see javax.lang.model.AnnotatedConstruct
*/
List getAllAnnotationMirrors(Element e);
/**
* Tests whether one type, method, or field hides another.
*
* @param hider the first element
* @param hidden the second element
* @return {@code true} if and only if the first element hides
* the second
* @jls 8.4.8 Inheritance, Overriding, and Hiding
*/
boolean hides(Element hider, Element hidden);
/**
* 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 {@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
* {@code type} parameter will simply be the class or interface
* directly enclosing {@code overrider} (the possibly-overriding
* method). For example, suppose {@code m1} represents the method
* {@code String.hashCode} and {@code m2} represents {@code
* Object.hashCode}. We can then ask whether {@code m1} overrides
* {@code m2} within the class {@code String} (it does):
*
* The returned file object is for the {@linkplain
* javax.lang.model.element##accurate_model reference
* representation} of the information used to construct the
* element. For example, if during compilation or annotation
* processing, a source file for class {@code Foo} is compiled
* into a class file, the file object returned for the element
* representing {@code 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 {@link
* UnsupportedOperationException} is thrown.
*
* In the context of annotation processing, a non-{@code 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 {@code
* null} may be returned. In annotation processing, if a
* {@linkplain javax.annotation.processing.Filer#createClassFile
* 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 {@code package-info} file. A package may exist and not
* have any {@code 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
* {@linkplain PackageElement#isUnnamed unnamed package} will have
* a {@code 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 {@code module-info} file. An {@linkplain
* ModuleElement#isUnnamed unnamed module} will have a {@code
* null} file since it cannot be declared in a compilation unit.
* An {@linkplain #isAutomaticModule automatic module} will have a
* {@code null} file since it is implicitly declared.
*
* If it has a file object, the file object for a top-level
* {@code 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 {@code 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 {@code package-info} source file, in
* which case the file for the {@code 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:
*
* For other lexically enclosed elements, such as {@linkplain
* VariableElement#getEnclosingElement() variables}, {@linkplain
* ExecutableElement#getEnclosingElement() methods, and
* constructors}, if they have a file object, the file object will
* be the object associated with the {@linkplain
* Element#getEnclosingElement() enclosing element} of the
* lexically enclosed element.
*
* @implSpec The default implementation unconditionally throws
* {@link UnsupportedOperationException}.
*
* @throws UnsupportedOperationException if this functionality is
* not supported
*
* @param e the element to find a file object for
* @since 18
*/
default javax.tools.JavaFileObject getFileObjectOf(Element e) {
throw new UnsupportedOperationException();
}
}
* {@code 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 {@code A} does not override a
* like-named method in interface {@code B}:
*
*
* {@code class A { public void m() {} } }
*
* When viewed as a member of a third class {@code C}, however,
* the method in {@code A} does override the one in {@code B}:
*
*
* {@code interface B { void m(); } }
* ...
* {@code m1 = ...; // A.m }
* {@code m2 = ...; // B.m }
* {@code assert ! elements.overrides(m1, m2,
* elements.getTypeElement("A")); }
*
* {@code class C extends A implements B {} }
*
* Consistent with the usage of the {@link Override @Override}
* annotation, if an interface declares a method
* override-equivalent to a {@code public} method of {@link Object
* java.lang.Object}, such a method of the interface is regarded
* as overriding the corresponding {@code Object} method; for
* example:
*
* {@snippet lang=java :
* interface I {
* @Override
* String toString();
* }
* ...
* assert elements.overrides(elementForItoString,
* elementForObjecttoString,
* elements.getTypeElement("I"));
* }
*
* @apiNote This method examines the method's name, signature, subclass relationship, and accessibility
* in determining whether one method overrides another, as specified in JLS {@jls 8.4.8.1}.
* In addition, an implementation may have stricter checks including method modifiers, return types and
* exception types as described in JLS {@jls 8.4.8.1} and {@jls 8.4.8.3}.
* Note that such additional compile-time checks are not guaranteed and may vary between implementations.
*
* @param overrider the first method, possible overrider
* @param overridden the second method, possibly being overridden
* @param type the class or interface of which the first method is a member
* @return {@code true} if and only if the first method overrides
* the second
* @jls 8.4.8 Inheritance, Overriding, and Hiding
* @jls 9.4.1 Inheritance and Overriding
*/
boolean overrides(ExecutableElement overrider, ExecutableElement overridden,
TypeElement type);
/**
* 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.
*
* @param value a primitive value or string
* @return the text of a constant expression
* @throws IllegalArgumentException if the argument is not a primitive
* value or string
*
* @see VariableElement#getConstantValue()
*/
String getConstantExpression(Object value);
/**
* 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.
*
* @param w the writer to print the output to
* @param elements the elements to print
*/
void printElements(java.io.Writer w, Element... elements);
/**
* {@return a name with the same sequence of characters as the
* argument}
*
* @param cs the character sequence to return as a name
*/
Name getName(CharSequence cs);
/**
* {@return {@code true} if the type element is a functional
* interface, {@code false} otherwise}
*
* @param type the type element being examined
* @jls 9.8 Functional Interfaces
* @since 1.8
*/
boolean isFunctionalInterface(TypeElement type);
/**
* {@return {@code true} if the module element is an automatic
* module, {@code false} otherwise}
*
* @implSpec
* The default implementation of this method returns {@code
* false}.
*
* @param module the module element being examined
* @jls 7.7.1 Dependences
* @since 17
*/
default boolean isAutomaticModule(ModuleElement module) {
return false;
}
/**
* {@return the class body of an {@code enum} constant if the
* argument is an {@code enum} constant declared with an optional
* class body, {@code null} otherwise}
*
* @implSpec
* The default implementation of this method throws {@code
* UnsupportedOperationException} if the argument is an {@code
* enum} constant and throws an {@code IllegalArgumentException}
* if it is not.
*
* @param enumConstant an enum constant
* @throws IllegalArgumentException if the argument is not an {@code enum} constant
* @jls 8.9.1 Enum Constants
* @since 22
*/
default TypeElement getEnumConstantBody(VariableElement enumConstant) {
switch(enumConstant.getKind()) {
case ENUM_CONSTANT -> throw new UnsupportedOperationException();
default -> throw new IllegalArgumentException("Argument not an enum constant");
}
}
/**
* Returns the record component for the given accessor. Returns
* {@code null} if the given method is not a record component
* accessor.
*
* @implSpec The default implementation of this method checks if the element
* enclosing the accessor has kind {@link ElementKind#RECORD RECORD}, if that is
* the case, then all the record components of the accessor's enclosing element
* are isolated by invoking {@link ElementFilter#recordComponentsIn(Iterable)}.
* If the accessor of at least one of the record components retrieved happens to
* be equal to the accessor passed as a parameter to this method, then that
* record component is returned, in any other case {@code null} is returned.
*
* @param accessor the method for which the record component should be found.
* @return the record component, or {@code null} if the given
* method is not a record component accessor
* @since 16
*/
default RecordComponentElement recordComponentFor(ExecutableElement accessor) {
if (accessor.getEnclosingElement().getKind() == ElementKind.RECORD) {
for (RecordComponentElement rec : ElementFilter.recordComponentsIn(accessor.getEnclosingElement().getEnclosedElements())) {
if (Objects.equals(rec.getAccessor(), accessor)) {
return rec;
}
}
}
return null;
}
/**
* {@return {@code true} if the executable element can be
* determined to be a canonical constructor of a record, {@code
* 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, {@code false} is returned.
*
* @implSpec
* The default implementation of this method unconditionally
* returns {@code false}.
*
* @param e the executable being examined
* @jls 8.10.4.1 Normal Canonical Constructors
* @since 20
*/
default boolean isCanonicalConstructor(ExecutableElement e) {
return false;
}
/**
* {@return {@code true} if the executable element can be
* determined to be a compact constructor of a record, {@code
* false} otherwise}
* By definition, a compact constructor is also a {@linkplain
* #isCanonicalConstructor(ExecutableElement) 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, {@code false} is returned.
*
* @implSpec
* The default implementation of this method unconditionally
* returns {@code false}.
*
* @param e the executable being examined
* @jls 8.10.4.2 Compact Canonical Constructors
* @since 20
*/
default boolean isCompactConstructor(ExecutableElement e) {
return false;
}
/**
* {@return the file object for this element or {@code null} if
* there is no such file object}
*
*
* ...
* {@code assert elements.overrides(m1, m2,
* elements.getTypeElement("C")); }
*
*
*
*
*