55 lines
2.2 KiB
Java
55 lines
2.2 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang3.builder;
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/**
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* <p>{@code Diffable} classes can be compared with other objects
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* for differences. The {@link DiffResult} object retrieved can be queried
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* for a list of differences or printed using the {@link DiffResult#toString()}.</p>
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*
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* <p>The calculation of the differences is <i>consistent with equals</i> if
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* and only if {@code d1.equals(d2)} implies {@code d1.diff(d2) == ""}.
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* It is strongly recommended that implementations are consistent with equals
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* to avoid confusion. Note that {@code null} is not an instance of any class
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* and {@code d1.diff(null)} should throw a {@code NullPointerException}.</p>
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*
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* <p>
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* {@code Diffable} classes lend themselves well to unit testing, in which a
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* easily readable description of the differences between an anticipated result and
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* an actual result can be retrieved. For example:
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* </p>
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* <pre>
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* Assert.assertEquals(expected.diff(result), expected, result);
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* </pre>
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*
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* @param <T> the type of objects that this object may be differentiated against
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* @since 3.3
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*/
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@FunctionalInterface
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public interface Diffable<T> {
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/**
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* <p>Retrieves a list of the differences between
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* this object and the supplied object.</p>
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*
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* @param obj the object to diff against, can be {@code null}
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* @return a list of differences
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* @throws NullPointerException if the specified object is {@code null}
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*/
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DiffResult<T> diff(T obj);
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}
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