1 /*
2 * Copyright (c) 2012, 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
23 * questions.
24 */
25
26 /*
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file:
31 *
32 * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
33 *
34 * All rights reserved.
35 *
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions are met:
38 *
39 * * Redistributions of source code must retain the above copyright notice,
40 * this list of conditions and the following disclaimer.
41 *
42 * * Redistributions in binary form must reproduce the above copyright notice,
43 * this list of conditions and the following disclaimer in the documentation
44 * and/or other materials provided with the distribution.
45 *
46 * * Neither the name of JSR-310 nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
51 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
52 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
53 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
54 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
55 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
56 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
57 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
58 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
59 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
60 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
61 */
62 package java.time.temporal;
63
64 import java.time.DateTimeException;
65 import java.time.Duration;
66 import java.time.Period;
67
68 /**
69 * Strategy for adding to a temporal object.
70 * <p>
71 * Adders are a key tool for modifying temporal objects.
72 * They exist to externalize the process of addition, permitting different
73 * approaches, as per the strategy design pattern.
74 * <p>
75 * There are two equivalent ways of using a {@code TemporalAdder}.
76 * The first is to invoke the method on this interface directly.
77 * The second is to use {@link Temporal#plus(TemporalAdder)}:
78 * <pre>
79 * // these two lines are equivalent, but the second approach is recommended
80 * dateTime = adder.addTo(dateTime);
81 * dateTime = dateTime.plus(adder);
82 * </pre>
83 * It is recommended to use the second approach, {@code plus(TemporalAdder)},
84 * as it is a lot clearer to read in code.
85 * <p>
86 * The {@link Period} and {@link Duration} classes implement this interface.
87 * Adders may also be defined by applications.
88 *
89 * <h3>Specification for implementors</h3>
90 * This interface places no restrictions on the mutability of implementations,
91 * however immutability is strongly recommended.
92 *
93 * @since 1.8
94 */
95 public interface TemporalAdder {
96
97 /**
98 * Adds to the specified temporal object.
99 * <p>
100 * This adds to the specified temporal object using the logic
101 * encapsulated in the implementing class.
102 * <p>
103 * There are two equivalent ways of using this method.
104 * The first is to invoke this method directly.
105 * The second is to use {@link Temporal#plus(TemporalAdder)}:
106 * <pre>
107 * // these two lines are equivalent, but the second approach is recommended
108 * dateTime = adder.addTo(dateTime);
109 * dateTime = dateTime.plus(adder);
110 * </pre>
111 * It is recommended to use the second approach, {@code plus(TemporalAdder)},
112 * as it is a lot clearer to read in code.
113 *
114 * <h3>Specification for implementors</h3>
115 * The implementation must take the input object and add to it.
116 * The implementation defines the logic of the addition and is responsible for
117 * documenting that logic. It may use any method on {@code Temporal} to
118 * query the temporal object and perform the addition.
119 * The returned object must have the same observable type as the input object
120 * <p>
121 * The input object must not be altered.
122 * Instead, an adjusted copy of the original must be returned.
123 * This provides equivalent, safe behavior for immutable and mutable temporal objects.
124 * <p>
125 * The input temporal object may be in a calendar system other than ISO.
126 * Implementations may choose to document compatibility with other calendar systems,
127 * or reject non-ISO temporal objects by {@link Queries#chrono() querying the chronology}.
128 * <p>
129 * This method may be called from multiple threads in parallel.
130 * It must be thread-safe when invoked.
131 *
132 * @param temporal the temporal object to adjust, not null
133 * @return an object of the same observable type with the addition made, not null
134 * @throws DateTimeException if unable to add
135 * @throws ArithmeticException if numeric overflow occurs
136 */
137 Temporal addTo(Temporal temporal);
138
139 }