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package javax.lang.model.element;

The nesting kind of a type element.
Type elements come in four varieties:
top-level, member, local, and anonymous.
Nesting kind is a non-standard term used here to denote this
classification.
Note that it is possible additional nesting kinds will be added
in future versions of the platform.
Example: The classes below are annotated with their nesting kind.
import java.lang.annotation.*;
import static java.lang.annotation.RetentionPolicy.*;
import javax.lang.model.element.*;
import static javax.lang.model.element.NestingKind.*;
@Nesting(TOP_LEVEL)
public class NestingExamples {
    @Nesting(MEMBER)
    static class MemberClass1{}
    @Nesting(MEMBER)
    class MemberClass2{}
    public static void main(String... argv) {
        @Nesting(LOCAL)
        class LocalClass{};
        Class<?>[] classes = {
            NestingExamples.class,
            MemberClass1.class,
            MemberClass2.class,
            LocalClass.class
        };
        for(Class<?> clazz : classes) {
            System.out.format("%s is %s%n",
                              clazz.getName(),
                              clazz.getAnnotation(Nesting.class).value());
        }
    }
}
@Retention(RUNTIME)
@interface Nesting {
    NestingKind value();
}

Author:
Joseph D. Darcy, Scott Seligman, Peter von der Ahé
Since:
1.6/**
 * The <i>nesting kind</i> of a type element.
 * Type elements come in four varieties:
 * top-level, member, local, and anonymous.
 * <i>Nesting kind</i> is a non-standard term used here to denote this
 * classification.
 *
 * <p>Note that it is possible additional nesting kinds will be added
 * in future versions of the platform.
 *
 * <p><b>Example:</b> The classes below are annotated with their nesting kind.
 * <blockquote><pre>
 *
 * import java.lang.annotation.*;
 * import static java.lang.annotation.RetentionPolicy.*;
 * import javax.lang.model.element.*;
 * import static javax.lang.model.element.NestingKind.*;
 *
 * &#64;Nesting(TOP_LEVEL)
 * public class NestingExamples {
 *     &#64;Nesting(MEMBER)
 *     static class MemberClass1{}
 *
 *     &#64;Nesting(MEMBER)
 *     class MemberClass2{}
 *
 *     public static void main(String... argv) {
 *         &#64;Nesting(LOCAL)
 *         class LocalClass{};
 *
 *         Class&lt;?&gt;[] classes = {
 *             NestingExamples.class,
 *             MemberClass1.class,
 *             MemberClass2.class,
 *             LocalClass.class
 *         };
 *
 *         for(Class&lt;?&gt; clazz : classes) {
 *             System.out.format("%s is %s%n",
 *                               clazz.getName(),
 *                               clazz.getAnnotation(Nesting.class).value());
 *         }
 *     }
 * }
 *
 * &#64;Retention(RUNTIME)
 * &#64;interface Nesting {
 *     NestingKind value();
 * }
 * </pre></blockquote>
 *
 * @author Joseph D. Darcy
 * @author Scott Seligman
 * @author Peter von der Ah&eacute;
 * @since 1.6
 */
public enum NestingKind {
    
A top-level class or interface, not contained within another
class or interface.
/**
     * A top-level class or interface, not contained within another
     * class or interface.
     */
    TOP_LEVEL,

    
A class or interface that is a named member of another class or
interface.
@jls
8.5 Member Class and Interface Declarations/**
     * A class or interface that is a named member of another class or
     * interface.
     * @jls 8.5 Member Class and Interface Declarations
     */
    MEMBER,

    
A named class or interface declared within a construct other
than a class or interface.
@jls
14.3 Local Class Declarations/**
     * A named class or interface declared within a construct other
     * than a class or interface.
     * @jls 14.3 Local Class Declarations
     */
    LOCAL,

    
A class without a name.
@jls
15.9.5 Anonymous Class Declarations/**
     * A class without a name.
     * @jls 15.9.5 Anonymous Class Declarations
     */
    ANONYMOUS;

    
Does this constant correspond to a nested type element?
A nested type element is any that is not top-level.
More specifically, an inner type element is any nested type element that is not static. 
Returns:
whether or not the constant is nested
@jls
14.3 Local Class Declarations/**
     * Does this constant correspond to a nested type element?
     * A <i>nested</i> type element is any that is not top-level.
     * More specifically, an <i>inner</i> type element is any nested type element that
     * is not {@linkplain Modifier#STATIC static}.
     * @return whether or not the constant is nested
     * @jls 14.3 Local Class Declarations
     */
    public boolean isNested() {
        return this != TOP_LEVEL;
    }
}