001/*
002 * ============================================================================
003 *  Copyright © 2002-2020 by Thomas Thrien.
004 *  All Rights Reserved.
005 * ============================================================================
006 *  Licensed to the public under the agreements of the GNU Lesser General Public
007 *  License, version 3.0 (the "License"). You may obtain a copy of the License at
008 *
009 *       http://www.gnu.org/licenses/lgpl.html
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
013 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
014 *  License for the specific language governing permissions and limitations
015 *  under the License.
016 */
017
018package org.tquadrat.foundation.annotation;
019
020import static java.lang.annotation.ElementType.TYPE;
021import static java.lang.annotation.RetentionPolicy.SOURCE;
022import static org.apiguardian.api.API.Status.STABLE;
023
024import java.lang.annotation.Documented;
025import java.lang.annotation.Retention;
026import java.lang.annotation.Target;
027
028import org.apiguardian.api.API;
029
030/**
031 *  <p>{@summary This is a marker annotation for a utility class.}</p>
032 *  <p>A utility class is a class that …</p>
033 *  <ul>
034 *      <li>… is final</li>
035 *      <li>… has only a private constructor that throws a
036 *      {@link org.tquadrat.foundation.exception.PrivateConstructorForStaticClassCalledError}
037 *      when called (that works only through reflection …) and therefore does
038 *      not allow any instances</li>
039 *      <li>… has only methods that are {@code static final}</li>
040 *      <li>… has only static final attributes (constants) and therefore should
041 *      not have any status</li>
042 *  </ul>
043 *  <p>The class {@code org.tquadrat.foundation.testutil.TestBaseClass} for the
044 *  {@code org.tquadrat.foundation.testutil} module provides a method
045 *  {@code validateAsStaticClass()} that tests most of these conditions.</p>
046 *
047 *  @extauthor Thomas Thrien - thomas.thrien@tquadrat.org
048 *  @version $Id: UtilityClass.java 966 2022-01-04 22:28:49Z tquadrat $
049 *
050 *  @since 0.1.0
051 */
052@ClassVersion( sourceVersion = "$Id: UtilityClass.java 966 2022-01-04 22:28:49Z tquadrat $" )
053@API( status = STABLE, since = "0.1.0" )
054@Documented
055@Retention( SOURCE )
056@Target( TYPE )
057public @interface UtilityClass
058{ /* Empty */ }
059//  @interface UtilityClass
060
061/*
062 *  End of File
063 */