TypeElement.java

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package javax.lang.model.element;

import java.util.List;
import javax.lang.model.type.*;
import javax.lang.model.util.*;

/**
 * Represents a class or interface program element.  Provides access
 * to information about the class or interface and its members.  Note
 * that an enum class and a record class are specialized kinds of
 * classes and an annotation interface is a specialized kind of
 * interface.
 *
 * <p> While a {@code TypeElement} represents a class or interface
 * <i>element</i>, a {@link DeclaredType} represents a class
 * or interface <i>type</i>, the latter being a use
 * (or <i>invocation</i>) of the former.
 * The distinction is most apparent with generic types,
 * for which a single element can define a whole
 * family of types.  For example, the element
 * {@code java.util.Set} corresponds to the parameterized types
 * {@code java.util.Set<String>} and {@code java.util.Set<Number>}
 * (and many others), and to the raw type {@code java.util.Set}.
 *
 * <p> Each method of this interface that returns a list of elements
 * will return them in the order that is natural for the underlying
 * source of program information.  For example, if the underlying
 * source of information is Java source code, then the elements will be
 * returned in source code order.
 *
 * @author Joseph D. Darcy
 * @author Scott Seligman
 * @author Peter von der Ah&eacute;
 * @see DeclaredType
 * @since 1.6
 */
public interface TypeElement extends Element, Parameterizable, QualifiedNameable {
    /**
     * Returns the type defined by this class or interface element,
     * returning the <i>prototypical</i> type for an element
     * representing a generic type.
     *
     * <p>A generic element defines a family of types, not just one.
     * If this is a generic element, a prototypical type is
     * returned which has the element's invocation on the
     * type variables corresponding to its own formal type parameters.
     * For example,
     * for the generic class element {@code C<N extends Number>},
     * the parameterized type {@code C<N>} is returned.
     * The {@link Types} utility interface has more general methods
     * for obtaining the full range of types defined by an element.
     *
     * @return the type defined by this type element
     *
     * @see Types#asMemberOf(DeclaredType, Element)
     * @see Types#getDeclaredType(TypeElement, TypeMirror...)
     */
    @Override
    TypeMirror asType();

    /**
     * Returns the fields, methods, constructors, record components,
     * and member classes and interfaces that are directly declared in
     * this class or interface.
     *
     * This includes any {@linkplain Elements.Origin#MANDATED
     * mandated} elements such as the (implicit) default constructor
     * and the implicit {@code values} and {@code valueOf} methods of
     * an enum class.
     *
     * @apiNote As a particular instance of the {@linkplain
     * javax.lang.model.element general accuracy requirements} and the
     * ordering behavior required of this interface, the list of
     * enclosed elements will be returned in the natural order for the
     * originating source of information about the class or interface.
     * For example, if the information about the class or interface is
     * originating from a source file, the elements will be returned
     * in source code order.  (However, in that case the ordering of
     * {@linkplain Elements.Origin#MANDATED implicitly declared}
     * elements, such as default constructors, is not specified.)
     *
     * @return the enclosed elements in proper order, or an empty list if none
     *
     * @jls 8.8.9 Default Constructor
     * @jls 8.9.3 Enum Members
     */
    @Override
    List<? extends Element> getEnclosedElements();

    /**
     * Returns the <i>nesting kind</i> of this class or interface element.
     *
     * @return the nesting kind of this class or interface element
     */
    NestingKind getNestingKind();

    /**
     * Returns the fully qualified name of this class or interface
     * element.  More precisely, it returns the <i>canonical</i> name.
     * For local and anonymous classes, which do not have canonical
     * names, an <a href=Name.html#empty_name>empty name</a> is
     * returned.
     *
     * <p>The name of a generic class or interface does not include any reference
     * to its formal type parameters.
     * For example, the fully qualified name of the interface
     * {@code java.util.Set<E>} is "{@code java.util.Set}".
     * Nested classes and interfaces use "{@code .}" as a separator, as in
     * "{@code java.util.Map.Entry}".
     *
     * @return the fully qualified name of this class or interface, or
     * an empty name if none
     *
     * @see Elements#getBinaryName
     * @jls 6.7 Fully Qualified Names and Canonical Names
     */
    Name getQualifiedName();

    /**
     * Returns the simple name of this class or interface element.
     *
     * For an anonymous class, an <a href=Name.html#empty_name> empty
     * name</a> is returned.
     *
     * @return the simple name of this class or interface,
     * an empty name for an anonymous class
     *
     */
    @Override
    Name getSimpleName();

    /**
     * Returns the direct superclass of this class or interface element.
     * If this class or interface element represents an interface or the class
     * {@code java.lang.Object}, then a {@link NoType}
     * with kind {@link TypeKind#NONE NONE} is returned.
     *
     * @return the direct superclass, or a {@code NoType} if there is none
     */
    TypeMirror getSuperclass();

    /**
     * Returns the interface types directly implemented by this class
     * or extended by this interface.
     *
     * @return the interface types directly implemented by this class
     * or extended by this interface, or an empty list if there are none
     */
    List<? extends TypeMirror> getInterfaces();

    /**
     * Returns the formal type parameters of this class or interface element
     * in declaration order.
     *
     * @return the formal type parameters, or an empty list
     * if there are none
     */
    List<? extends TypeParameterElement> getTypeParameters();

    /**
     * Returns the record components of this class or interface
     * element in declaration order.
     *
     * @implSpec The default implementations of this method returns an
     * empty and unmodifiable list.
     *
     * @return the record components, or an empty list if there are
     * none
     *
     * @since 16
     */
    default List<? extends RecordComponentElement> getRecordComponents() {
        return List.of();
    }

    /**
     * Returns the permitted classes of this class or interface
     * element in declaration order.
     *
     * @implSpec The default implementations of this method returns an
     * empty and unmodifiable list.
     *
     * @return the permitted classes, or an empty list if there are none
     *
     * @since 15
     */
    @jdk.internal.javac.PreviewFeature(feature=jdk.internal.javac.PreviewFeature.Feature.SEALED_CLASSES,
                                 reflective=true)
    default List<? extends TypeMirror> getPermittedSubclasses() {
        return List.of();
    }

    /**
     * Returns the package of a top-level class or interface and
     * returns the immediately lexically enclosing element for a
     * {@linkplain NestingKind#isNested nested} class or interface.
     *
     * @return the package of a top-level class or interface, the immediately
     * lexically enclosing element for a nested class or interface
     */
    @Override
    Element getEnclosingElement();
}