1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.lang3.builder;
18
19 import java.lang.reflect.Type;
20 import java.util.Objects;
21
22 import org.apache.commons.lang3.ObjectUtils;
23 import org.apache.commons.lang3.reflect.TypeUtils;
24 import org.apache.commons.lang3.tuple.Pair;
25
26 /**
27 * A {@link Diff} contains the differences between two {@link Diffable} class
28 * fields.
29 *
30 * <p>
31 * Typically, {@link Diff}s are retrieved by using a {@link DiffBuilder} to
32 * produce a {@link DiffResult}, containing the differences between two objects.
33 * </p>
34 *
35 * @param <T>
36 * The type of object contained within this {@link Diff}. Differences
37 * between primitive objects are stored as their Object wrapper
38 * equivalent.
39 * @since 3.3
40 */
41 public abstract class Diff<T> extends Pair<T, T> {
42
43 private static final long serialVersionUID = 1L;
44
45 /** The field type. */
46 private final Type type;
47
48 /** The field name. */
49 private final String fieldName;
50
51 /**
52 * Constructs a new {@link Diff} for the given field name.
53 *
54 * @param fieldName
55 * the field name
56 */
57 protected Diff(final String fieldName) {
58 this.fieldName = Objects.requireNonNull(fieldName);
59 this.type = ObjectUtils.defaultIfNull(TypeUtils.getTypeArguments(getClass(), Diff.class).get(Diff.class.getTypeParameters()[0]), Object.class);
60 }
61
62 Diff(final String fieldName, final Type type) {
63 this.fieldName = Objects.requireNonNull(fieldName);
64 this.type = Objects.requireNonNull(type);
65 }
66
67 /**
68 * Gets the name of the field.
69 *
70 * @return the field name
71 */
72 public final String getFieldName() {
73 return fieldName;
74 }
75
76 /**
77 * Gets the type of the field.
78 *
79 * @return the field type
80 * @deprecated Unused, will be removed in 4.0.0.
81 */
82 @Deprecated
83 public final Type getType() {
84 return type;
85 }
86
87 /**
88 * Throws {@link UnsupportedOperationException}.
89 *
90 * @param value
91 * ignored
92 * @return nothing
93 */
94 @Override
95 public final T setValue(final T value) {
96 throw new UnsupportedOperationException("Cannot alter Diff object.");
97 }
98
99 /**
100 * Returns a {@link String} representation of the {@link Diff}, with the
101 * following format:
102 *
103 * <pre>
104 * [fieldname: left-value, right-value]
105 * </pre>
106 *
107 * @return the string representation
108 */
109 @Override
110 public final String toString() {
111 return String.format("[%s: %s, %s]", fieldName, getLeft(), getRight());
112 }
113 }