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src/share/classes/javax/lang/model/util/SimpleElementVisitor8.java@09f65aad4759 (annotated)

src/share/classes/javax/lang/model/util/SimpleElementVisitor8.java

Wed, 23 Jan 2013 20:11:07 -0800

author

darcy

date

Wed, 23 Jan 2013 20:11:07 -0800

changeset 1522

09f65aad4759

parent 1357

c75be5bc5283

child 2525

2eb010b6cb22

permissions

-rw-r--r--

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

darcy@1054	1	/*
darcy@1522	2	* Copyright (c) 2011, 2013, Oracle and/or its affiliates. All rights reserved.
darcy@1054	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
darcy@1054	4	*
darcy@1054	5	* This code is free software; you can redistribute it and/or modify it
darcy@1054	6	* under the terms of the GNU General Public License version 2 only, as
darcy@1054	7	* published by the Free Software Foundation. Oracle designates this
darcy@1054	8	* particular file as subject to the "Classpath" exception as provided
darcy@1054	9	* by Oracle in the LICENSE file that accompanied this code.
darcy@1054	10	*
darcy@1054	11	* This code is distributed in the hope that it will be useful, but WITHOUT
darcy@1054	12	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
darcy@1054	13	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
darcy@1054	14	* version 2 for more details (a copy is included in the LICENSE file that
darcy@1054	15	* accompanied this code).
darcy@1054	16	*
darcy@1054	17	* You should have received a copy of the GNU General Public License version
darcy@1054	18	* 2 along with this work; if not, write to the Free Software Foundation,
darcy@1054	19	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
darcy@1054	20	*
darcy@1054	21	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
darcy@1054	22	* or visit www.oracle.com if you need additional information or have any
darcy@1054	23	* questions.
darcy@1054	24	*/
darcy@1054	25
darcy@1054	26	package javax.lang.model.util;
darcy@1054	27
darcy@1054	28	import javax.annotation.processing.SupportedSourceVersion;
darcy@1054	29	import javax.lang.model.SourceVersion;
darcy@1054	30	import static javax.lang.model.SourceVersion.*;
darcy@1054	31
darcy@1054	32	/**
darcy@1054	33	* A simple visitor of program elements with default behavior
darcy@1054	34	* appropriate for the {@link SourceVersion#RELEASE_8 RELEASE_8}
darcy@1054	35	* source version.
darcy@1054	36	*
darcy@1054	37	* Visit methods corresponding to {@code RELEASE_7} and earlier
darcy@1054	38	* language constructs call {@link #defaultAction defaultAction},
darcy@1054	39	* passing their arguments to {@code defaultAction}'s corresponding
darcy@1054	40	* parameters.
darcy@1054	41	*
darcy@1054	42	* <p> Methods in this class may be overridden subject to their
darcy@1054	43	* general contract. Note that annotating methods in concrete
darcy@1054	44	* subclasses with {@link java.lang.Override @Override} will help
darcy@1054	45	* ensure that methods are overridden as intended.
darcy@1054	46	*
darcy@1054	47	* <p> <b>WARNING:</b> The {@code ElementVisitor} interface
darcy@1054	48	* implemented by this class may have methods added to it in the
darcy@1054	49	* future to accommodate new, currently unknown, language structures
darcy@1054	50	* added to future versions of the Java&trade; programming language.
darcy@1054	51	* Therefore, methods whose names begin with {@code "visit"} may be
darcy@1054	52	* added to this class in the future; to avoid incompatibilities,
darcy@1054	53	* classes which extend this class should not declare any instance
darcy@1054	54	* methods with names beginning with {@code "visit"}.
darcy@1054	55	*
darcy@1054	56	* <p>When such a new visit method is added, the default
darcy@1054	57	* implementation in this class will be to call the {@link
darcy@1054	58	* #visitUnknown visitUnknown} method. A new simple element visitor
darcy@1054	59	* class will also be introduced to correspond to the new language
darcy@1054	60	* level; this visitor will have different default behavior for the
darcy@1054	61	* visit method in question. When the new visitor is introduced, all
darcy@1054	62	* or portions of this visitor may be deprecated.
darcy@1054	63	*
darcy@1522	64	* <p>Note that adding a default implementation of a new visit method
darcy@1522	65	* in a visitor class will occur instead of adding a <em>default
darcy@1522	66	* method</em> directly in the visitor interface since a Java SE 8
darcy@1522	67	* language feature cannot be used to this version of the API since
darcy@1522	68	* this version is required to be runnable on Java SE 7
darcy@1522	69	* implementations. Future versions of the API that are only required
darcy@1522	70	* to run on Java SE 8 and later may take advantage of default methods
darcy@1522	71	* in this situation.
darcy@1522	72	*
darcy@1054	73	* @param <R> the return type of this visitor's methods. Use {@code Void}
darcy@1054	74	* for visitors that do not need to return results.
darcy@1054	75	* @param <P> the type of the additional parameter to this visitor's methods. Use {@code Void}
darcy@1054	76	* for visitors that do not need an additional parameter.
darcy@1054	77	*
darcy@1054	78	* @see SimpleElementVisitor6
darcy@1054	79	* @see SimpleElementVisitor7
darcy@1054	80	* @since 1.8
darcy@1054	81	*/
darcy@1054	82	@SupportedSourceVersion(RELEASE_8)
darcy@1054	83	public class SimpleElementVisitor8<R, P> extends SimpleElementVisitor7<R, P> {
darcy@1054	84	/**
darcy@1054	85	* Constructor for concrete subclasses; uses {@code null} for the
darcy@1054	86	* default value.
darcy@1054	87	*/
darcy@1054	88	protected SimpleElementVisitor8(){
darcy@1054	89	super(null);
darcy@1054	90	}
darcy@1054	91
darcy@1054	92	/**
darcy@1054	93	* Constructor for concrete subclasses; uses the argument for the
darcy@1054	94	* default value.
darcy@1054	95	*
darcy@1054	96	* @param defaultValue the value to assign to {@link #DEFAULT_VALUE}
darcy@1054	97	*/
darcy@1054	98	protected SimpleElementVisitor8(R defaultValue){
darcy@1054	99	super(defaultValue);
darcy@1054	100	}
darcy@1054	101	}