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
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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
63 /**
64 * <p>
65 * Access to date and time using fields and units, and date time adjusters.
66 * </p>
67 * <p>
68 * This package expands on the base package to provide additional functionality for
69 * more powerful use cases. Support is included for:
70 * </p>
71 * <ul>
72 * <li>Units of date-time, such as years, months, days and hours</li>
73 * <li>Fields of date-time, such as month-of-year, day-of-week or hour-of-day</li>
74 * <li>Date-time adjustment functions</li>
75 * <li>Different definitions of weeks</li>
76 * </ul>
77 *
78 * <h3>Fields and Units</h3>
79 * <p>
80 * Dates and times are expressed in terms of fields and units.
81 * A unit is used to measure an amount of time, such as years, days or minutes.
82 * All units implement {@link java.time.temporal.TemporalUnit}.
83 * The set of well known units is defined in {@link java.time.temporal.ChronoUnit}, such as {@code DAYS}.
84 * The unit interface is designed to allow application defined units.
85 * </p>
86 * <p>
87 * A field is used to express part of a larger date-time, such as year, month-of-year or second-of-minute.
88 * All fields implement {@link java.time.temporal.TemporalField}.
89 * The set of well known fields are defined in {@link java.time.temporal.ChronoField}, such as {@code HOUR_OF_DAY}.
90 * Additional fields are defined by {@link java.time.temporal.JulianFields}, {@link java.time.temporal.WeekFields}
91 * and {@link java.time.temporal.IsoFields}.
92 * The field interface is designed to allow application defined fields.
93 * </p>
94 * <p>
95 * This package provides tools that allow the units and fields of date and time to be accessed
96 * in a general way most suited for frameworks.
97 * {@link java.time.temporal.Temporal} provides the abstraction for date time types that support fields.
98 * Its methods support getting the value of a field, creating a new date time with the value of
99 * a field modified, and querying for additional information, typically used to extract the offset or time-zone.
100 * </p>
101 * <p>
102 * One use of fields in application code is to retrieve fields for which there is no convenience method.
103 * For example, getting the day-of-month is common enough that there is a method on {@code LocalDate}
104 * called {@code getDayOfMonth()}. However for more unusual fields it is necessary to use the field.
105 * For example, {@code date.get(ChronoField.ALIGNED_WEEK_OF_MONTH)}.
106 * The fields also provide access to the range of valid values.
107 * </p>
108 *
109 * <h3>Adjustment and Query</h3>
110 * <p>
111 * A key part of the date-time problem space is adjusting a date to a new, related value,
112 * such as the "last day of the month", or "next Wednesday".
113 * These are modeled as functions that adjust a base date-time.
114 * The functions implement {@link java.time.temporal.TemporalAdjuster} and operate on {@code Temporal}.
115 * A set of common functions are provided in {@link java.time.temporal.TemporalAdjusters}.
116 * For example, to find the first occurrence of a day-of-week after a given date, use
117 * {@link java.time.temporal.TemporalAdjusters#next(DayOfWeek)}, such as
118 * {@code date.with(next(MONDAY))}.
119 * Applications can also define adjusters by implementing {@link java.time.temporal.TemporalAdjuster}.
120 * </p>
121 * <p>
122 * The {@link java.time.temporal.TemporalAmount} interface models amounts of relative time.
123 * </p>
124 * <p>
125 * In addition to adjusting a date-time, an interface is provided to enable querying via
126 * {@link java.time.temporal.TemporalQuery}.
127 * The most common implementations of the query interface are method references.
128 * The {@code from(TemporalAccessor)} methods on major classes can all be used, such as
129 * {@code LocalDate::from} or {@code Month::from}.
130 * Further implementations are provided in {@link java.time.temporal.TemporalQueries} as static methods.
131 * Applications can also define queries by implementing {@link java.time.temporal.TemporalQuery}.
132 * </p>
133 *
134 * <h3>Weeks</h3>
135 * <p>
136 * Different locales have different definitions of the week.
137 * For example, in Europe the week typically starts on a Monday, while in the US it starts on a Sunday.
138 * The {@link java.time.temporal.WeekFields} class models this distinction.
139 * </p>
140 * <p>
141 * The ISO calendar system defines an additional week-based division of years.
142 * This defines a year based on whole Monday to Monday weeks.
143 * This is modeled in {@link java.time.temporal.IsoFields}.
144 * </p>
145 *
146 * <h3>Package specification</h3>
147 * <p>
148 * Unless otherwise noted, passing a null argument to a constructor or method in any class or interface
149 * in this package will cause a {@link java.lang.NullPointerException NullPointerException} to be thrown.
150 * The Javadoc "@param" definition is used to summarise the null-behavior.
151 * The "@throws {@link java.lang.NullPointerException}" is not explicitly documented in each method.
152 * </p>
153 * <p>
154 * All calculations should check for numeric overflow and throw either an {@link java.lang.ArithmeticException}
155 * or a {@link java.time.DateTimeException}.
156 * </p>
157 * @since 1.8
158 */
159 package java.time.temporal;