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package javax.annotation.processing;

import javax.lang.model.element.Element;
import javax.lang.model.element.TypeElement;
import java.util.LinkedHashSet;
import java.util.Collections;
import java.util.Set;
import java.lang.annotation.Annotation;


An annotation processing tool framework will provide an annotation processor with an object
implementing this interface so that the processor can query for information about a round of annotation processing. 
Author:Joseph D. Darcy, Scott Seligman, Peter von der Ahé
Since:1.6
/**
 * An annotation processing tool framework will {@linkplain
 * Processor#process provide an annotation processor with an object
 * implementing this interface} so that the processor can query for
 * information about a round of annotation processing.
 *
 * @author Joseph D. Darcy
 * @author Scott Seligman
 * @author Peter von der Ahé
 * @since 1.6
 */
public interface RoundEnvironment {
    
Returns true if types generated by this round will not be subject to a subsequent round of annotation processing; returns false otherwise. 
Returns:true if types generated by this round will not be subject to a subsequent round of annotation processing; returns false otherwise
/**
     * Returns {@code true} if types generated by this round will not
     * be subject to a subsequent round of annotation processing;
     * returns {@code false} otherwise.
     *
     * @return {@code true} if types generated by this round will not
     * be subject to a subsequent round of annotation processing;
     * returns {@code false} otherwise
     */
    boolean processingOver();

    
Returns true if an error was raised in the prior round of processing; returns false otherwise. 
Returns:true if an error was raised in the prior round of processing; returns false otherwise
/**
     * Returns {@code true} if an error was raised in the prior round
     * of processing; returns {@code false} otherwise.
     *
     * @return {@code true} if an error was raised in the prior round
     * of processing; returns {@code false} otherwise
     */
    boolean errorRaised();

    
Returns the root elements for annotation processing generated by the prior round. 
Returns:the root elements for annotation processing generated
by the prior round, or an empty set if there were none
/**
     * Returns the {@linkplain Processor root elements} for annotation processing generated
     * by the prior round.
     *
     * @return the root elements for annotation processing generated
     * by the prior round, or an empty set if there were none
     */
    Set<? extends Element> getRootElements();

    
Returns the elements annotated with the given annotation type.
The annotation may appear directly or be inherited.  Only
package elements, module elements, and type elements included in this round of annotation processing, or declarations of members, constructors, parameters, or type parameters declared within those, are returned. Included type elements are root types and any member types nested within them. Elements of a package are not considered included simply because a package-info file for that package was created. Likewise, elements of a module are not considered included simply because a module-info file for that module was created 
Params:
  • a –  annotation type being requested
Throws:
Returns:the elements annotated with the given annotation type,
or an empty set if there are none
/**
     * Returns the elements annotated with the given annotation type.
     * The annotation may appear directly or be inherited.  Only
     * package elements, module elements, and type elements <i>included</i> in this
     * round of annotation processing, or declarations of members,
     * constructors, parameters, or type parameters declared within
     * those, are returned.  Included type elements are {@linkplain
     * #getRootElements root types} and any member types nested within
     * them.  Elements of a package are not considered included simply
     * because a {@code package-info} file for that package was
     * created.
     * Likewise, elements of a module are not considered included
     * simply because a {@code module-info} file for that module was
     * created
     *
     * @param a  annotation type being requested
     * @return the elements annotated with the given annotation type,
     * or an empty set if there are none
     * @throws IllegalArgumentException if the argument does not
     * represent an annotation type
     */
    Set<? extends Element> getElementsAnnotatedWith(TypeElement a);

    
Returns the elements annotated with one or more of the given
annotation types.

Params:
  • annotations –  annotation types being requested
Throws:
API Note:This method may be useful when processing repeating
annotations by looking for an annotation type and its
containing annotation type at the same time.
Implementation Requirements:The default implementation of this method creates an empty result set, iterates over the annotations in the argument array calling getElementsAnnotatedWith(TypeElement) on each annotation and adding those results to the result set. Finally, the contents of the result set are returned as an unmodifiable set.
Returns:the elements annotated with one or more of the given
annotation types, or an empty set if there are none
@jls9.6.3 Repeatable Annotation Types
Since:9
/**
     * Returns the elements annotated with one or more of the given
     * annotation types.
     *
     * @apiNote This method may be useful when processing repeating
     * annotations by looking for an annotation type and its
     * containing annotation type at the same time.
     *
     * @implSpec The default implementation of this method creates an
     * empty result set, iterates over the annotations in the argument
     * array calling {@link #getElementsAnnotatedWith(TypeElement)} on
     * each annotation and adding those results to the result
     * set. Finally, the contents of the result set are returned as an
     * unmodifiable set.
     *
     * @param annotations  annotation types being requested
     * @return the elements annotated with one or more of the given
     * annotation types, or an empty set if there are none
     * @throws IllegalArgumentException if the any elements of the
     * argument set do not represent an annotation type
     * @jls 9.6.3 Repeatable Annotation Types
     * @since 9
     */
    default Set<? extends Element> getElementsAnnotatedWithAny(TypeElement... annotations){
        // Use LinkedHashSet rather than HashSet for predictability
        Set<Element> result = new LinkedHashSet<>();
        for (TypeElement annotation : annotations) {
            result.addAll(getElementsAnnotatedWith(annotation));
        }
        return Collections.unmodifiableSet(result);
    }

    
Returns the elements annotated with the given annotation type.
The annotation may appear directly or be inherited.  Only
package elements, module elements, and type elements included in this round of annotation processing, or declarations of members, constructors, parameters, or type parameters declared within those, are returned. Included type elements are root types and any member types nested within them. Elements in a package are not considered included simply because a package-info file for that package was created. Likewise, elements of a module are not considered included simply because a module-info file for that module was created 
Params:
  • a –  annotation type being requested
Throws:
Returns:the elements annotated with the given annotation type,
or an empty set if there are none
/**
     * Returns the elements annotated with the given annotation type.
     * The annotation may appear directly or be inherited.  Only
     * package elements, module elements, and type elements <i>included</i> in this
     * round of annotation processing, or declarations of members,
     * constructors, parameters, or type parameters declared within
     * those, are returned.  Included type elements are {@linkplain
     * #getRootElements root types} and any member types nested within
     * them.  Elements in a package are not considered included simply
     * because a {@code package-info} file for that package was
     * created.
     * Likewise, elements of a module are not considered included
     * simply because a {@code module-info} file for that module was
     * created
     *
     * @param a  annotation type being requested
     * @return the elements annotated with the given annotation type,
     * or an empty set if there are none
     * @throws IllegalArgumentException if the argument does not
     * represent an annotation type
     */
    Set<? extends Element> getElementsAnnotatedWith(Class<? extends Annotation> a);

    
Returns the elements annotated with one or more of the given
annotation types.

Params:
  • annotations –  annotation types being requested
Throws:
API Note:This method may be useful when processing repeating
annotations by looking for an annotation type and its
containing annotation type at the same time.
Implementation Requirements:The default implementation of this method creates an empty result set, iterates over the annotations in the argument set calling getElementsAnnotatedWith(Class<? extends Annotation>) on each annotation and adding those results to the result set. Finally, the contents of the result set are returned as an unmodifiable set.
Returns:the elements annotated with one or more of the given
annotation types, or an empty set if there are none
@jls9.6.3 Repeatable Annotation Types
Since:9
/**
     * Returns the elements annotated with one or more of the given
     * annotation types.
     *
     * @apiNote This method may be useful when processing repeating
     * annotations by looking for an annotation type and its
     * containing annotation type at the same time.
     *
     * @implSpec The default implementation of this method creates an
     * empty result set, iterates over the annotations in the argument
     * set calling {@link #getElementsAnnotatedWith(Class)} on
     * each annotation and adding those results to the result
     * set. Finally, the contents of the result set are returned as an
     * unmodifiable set.
     *
     * @param annotations  annotation types being requested
     * @return the elements annotated with one or more of the given
     * annotation types, or an empty set if there are none
     * @throws IllegalArgumentException if the any elements of the
     * argument set do not represent an annotation type
     * @jls 9.6.3 Repeatable Annotation Types
     * @since 9
     */
    default Set<? extends Element> getElementsAnnotatedWithAny(Set<Class<? extends Annotation>> annotations){
        // Use LinkedHashSet rather than HashSet for predictability
        Set<Element> result = new LinkedHashSet<>();
        for (Class<? extends Annotation> annotation : annotations) {
            result.addAll(getElementsAnnotatedWith(annotation));
        }
        return Collections.unmodifiableSet(result);
    }
}