jdk8-mips64-public/langtools: src/share/classes/javax/lang/model/util/AbstractAnnotationValueVisitor8.java@09f65aad4759

8006264: Add explanation of why default methods cannot be used in JDK 8 javax.lang.model
Reviewed-by: jjg

     1 /*

     2  * Copyright (c) 2011, 2013, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

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    24  */

    26 package javax.lang.model.util;

    28 import static javax.lang.model.SourceVersion.*;

    29 import javax.lang.model.SourceVersion;

    30 import javax.annotation.processing.SupportedSourceVersion;

    32 /**

    33  * A skeletal visitor for annotation values with default behavior

    34  * appropriate for the {@link SourceVersion#RELEASE_8 RELEASE_8}

    35  * source version.

    36  *

    37  * <p> <b>WARNING:</b> The {@code AnnotationValueVisitor} interface

    38  * implemented by this class may have methods added to it in the

    39  * future to accommodate new, currently unknown, language structures

    40  * added to future versions of the Java&trade; programming language.

    41  * Therefore, methods whose names begin with {@code "visit"} may be

    42  * added to this class in the future; to avoid incompatibilities,

    43  * classes which extend this class should not declare any instance

    44  * methods with names beginning with {@code "visit"}.

    45  *

    46  * <p>When such a new visit method is added, the default

    47  * implementation in this class will be to call the {@link

    48  * #visitUnknown visitUnknown} method.  A new abstract annotation

    49  * value visitor class will also be introduced to correspond to the

    50  * new language level; this visitor will have different default

    51  * behavior for the visit method in question.  When the new visitor is

    52  * introduced, all or portions of this visitor may be deprecated.

    53  *

    54  * <p>Note that adding a default implementation of a new visit method

    55  * in a visitor class will occur instead of adding a <em>default

    56  * method</em> directly in the visitor interface since a Java SE 8

    57  * language feature cannot be used to this version of the API since

    58  * this version is required to be runnable on Java SE 7

    59  * implementations.  Future versions of the API that are only required

    60  * to run on Java SE 8 and later may take advantage of default methods

    61  * in this situation.

    62  *

    63  * @param <R> the return type of this visitor's methods

    64  * @param <P> the type of the additional parameter to this visitor's methods.

    65  *

    66  * @see AbstractAnnotationValueVisitor6

    67  * @see AbstractAnnotationValueVisitor7

    68  * @since 1.8

    69  */

    70 @SupportedSourceVersion(RELEASE_8)

    71 public abstract class AbstractAnnotationValueVisitor8<R, P> extends AbstractAnnotationValueVisitor7<R, P> {

    73     /**

    74      * Constructor for concrete subclasses to call.

    75      */

    76     protected AbstractAnnotationValueVisitor8() {

    77         super();

    78     }

    79 }

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