javax.lang.model.element (Java SE 11 & JDK 11 )
Keywords: javax.lang.model.element package

Module java.compiler

# Package javax.lang.model.element

Interfaces used to model elements of the Java programming language. The term "element" in this package is used to refer to program elements, the declared entities that make up a program. Elements include classes, interfaces, methods, constructors, and fields. The interfaces in this package do not model the structure of a program inside a method body; for example there is no representation of a `for` loop or `try`-`finally` block. However, the interfaces can model some structures only appearing inside method bodies, such as local variables and anonymous classes.

When used in the context of annotation processing, an accurate model of the element being represented must be returned. As this is a language model, the source code provides the fiducial (reference) representation of the construct in question rather than a representation in an executable output like a class file. Executable output may serve as the basis for creating a modeling element. However, the process of translating source code to executable output may not permit recovering some aspects of the source code representation. For example, annotations with source retention cannot be recovered from class files and class files might not be able to provide source position information. Names of parameters may not be recoverable from class files. The modifiers on an element created from a class file may differ in some cases from an element for the same declaration created from a source file including:

- `strictfp` on a class or interface
- `final` on a parameter
- `protected`, `private`, and `static` on classes and interfaces

Some elements which are mandated may not be marked as such when created from class files. Additionally, synthetic constructs in a class file, such as accessor methods used in implementing nested classes and bridge methods used in implementing covariant returns, are translation artifacts strictly outside of this model. However, when operating on class files, it is helpful be able to operate on such elements, screening them out when appropriate.

During annotation processing, operating on incomplete or erroneous programs is necessary; however, there are fewer guarantees about the nature of the resulting model. If the source code is not syntactically well-formed or has some other irrecoverable error that could not be removed by the generation of new types, a model may or may not be provided as a quality of implementation issue. If a program is syntactically valid but erroneous in some other fashion, any returned model must have no less information than if all the method bodies in the program were replaced by `"throw new RuntimeException();"`. If a program refers to a missing type Xyz, the returned model must contain no less information than if the declaration of type Xyz were assumed to be `"class Xyz {}"`, `"interface Xyz {}"`, `"enum Xyz {}"`, or `"@interface Xyz {}"`. If a program refers to a missing type `Xyz<K1, ... ,Kn>`, the returned model must contain no less information than if the declaration of Xyz were assumed to be `"class Xyz<T1, ... ,Tn> {}"` or `"interface Xyz<T1, ... ,Tn> {}"`

Unless otherwise specified in a particular implementation, the collections returned by methods in this package should be expected to be unmodifiable by the caller and unsafe for concurrent access.

Unless otherwise specified, methods in this package will throw a `NullPointerException` if given a `null` argument.

Since:
  1.6

- Interface Summary
  Interface | Description
  --- | ---
  AnnotationMirror | Represents an annotation.
  AnnotationValue | Represents a value of an annotation type element.
  AnnotationValueVisitor<R,​P> | A visitor of the values of annotation type elements, using a variant of the visitor design pattern.
  Element | Represents a program element such as a module, package, class, or method.
  ElementVisitor<R,​P> | A visitor of program elements, in the style of the visitor design pattern.
  ExecutableElement | Represents a method, constructor, or initializer (static or instance) of a class or interface, including annotation type elements.
  ModuleElement | Represents a module program element.
  ModuleElement.Directive | Represents a directive within the declaration of this module.
  ModuleElement.DirectiveVisitor<R,​P> | A visitor of module directives, in the style of the visitor design pattern.
  ModuleElement.ExportsDirective | An exported package of a module.
  ModuleElement.OpensDirective | An opened package of a module.
  ModuleElement.ProvidesDirective | An implementation of a service provided by a module.
  ModuleElement.RequiresDirective | A dependency of a module.
  ModuleElement.UsesDirective | A reference to a service used by a module.
  Name | An immutable sequence of characters.
  PackageElement | Represents a package program element.
  Parameterizable | A mixin interface for an element that has type parameters.
  QualifiedNameable | A mixin interface for an element that has a qualified name.
  TypeElement | Represents a class or interface program element.
  TypeParameterElement | Represents a formal type parameter of a generic class, interface, method, or constructor element.
  VariableElement | Represents a field, `enum` constant, method or constructor parameter, local variable, resource variable, or exception parameter.

- Enum Summary
  Enum | Description
  --- | ---
  ElementKind | The `kind` of an element.
  Modifier | Represents a modifier on a program element such as a class, method, or field.
  ModuleElement.DirectiveKind | The `kind` of a directive.
  NestingKind | The nesting kind of a type element.

- Exception Summary
  Exception | Description
  --- | ---
  UnknownAnnotationValueException | Indicates that an unknown kind of annotation value was encountered.
  UnknownDirectiveException | Indicates that an unknown kind of module directive was encountered.
  UnknownElementException | Indicates that an unknown kind of element was encountered.