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Java > Open Source Codes > org > joda > time > chrono > BasicFixedMonthChronology


1 /*
2  * Copyright 2001-2005 Stephen Colebourne
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.joda.time.chrono;
17
18 import org.joda.time.Chronology;
19 import org.joda.time.DateTimeConstants;
20
21 /**
22  * Abstract implementation of a calendar system based around fixed length months.
23  * <p>
24  * As the month length is fixed various calculations can be optimised.
25  * This implementation assumes any additional days after twelve
26  * months fall into a thirteenth month.
27  * <p>
28  * BasicFixedMonthChronology is thread-safe and immutable, and all
29  * subclasses must be as well.
30  *
31  * @author Brian S O'Neill
32  * @author Stephen Colebourne
33  * @since 1.2, refactored from CopticChronology
34  */
35 abstract class BasicFixedMonthChronology extends BasicChronology {
36
37     /** Serialization lock */
38     private static final long serialVersionUID = 261387371998L;
39
40     /** The length of the month. */
41     static final int MONTH_LENGTH = 30;
42
43     /** The typical millis per year. */
44     static final long MILLIS_PER_YEAR =
45         (long) (365.25 * DateTimeConstants.MILLIS_PER_DAY);
46
47     /** The length of the month in millis. */
48     static final long MILLIS_PER_MONTH = ((long) MONTH_LENGTH) * DateTimeConstants.MILLIS_PER_DAY;
49
50     //-----------------------------------------------------------------------
51 /**
52      * Restricted constructor.
53      *
54      * @param base the base chronology
55      * @param param the init parameter
56      * @param minDaysInFirstWeek the minimum days in the first week
57      */
58     BasicFixedMonthChronology(Chronology base, Object JavaDoc param, int minDaysInFirstWeek) {
59         super(base, param, minDaysInFirstWeek);
60     }
61
62     //-----------------------------------------------------------------------
63 long setYear(long instant, int year) {
64         // optimsed implementation of set, due to fixed months
65 int thisYear = getYear(instant);
66         int dayOfYear = getDayOfYear(instant, thisYear);
67         int millisOfDay = getMillisOfDay(instant);
68
69         if (dayOfYear > 365) {
70             // Current year is leap, and day is leap.
71 if (!isLeapYear(year)) {
72                 // Moving to a non-leap year, leap day doesn't exist.
73 dayOfYear--;
74             }
75         }
76
77         instant = getYearMonthDayMillis(year, 1, dayOfYear);
78         instant += millisOfDay;
79         return instant;
80     }
81
82     //-----------------------------------------------------------------------
83 long getYearDifference(long minuendInstant, long subtrahendInstant) {
84         // optimsed implementation of getDifference, due to fixed months
85 int minuendYear = getYear(minuendInstant);
86         int subtrahendYear = getYear(subtrahendInstant);
87
88         // Inlined remainder method to avoid duplicate calls to get.
89 long minuendRem = minuendInstant - getYearMillis(minuendYear);
90         long subtrahendRem = subtrahendInstant - getYearMillis(subtrahendYear);
91
92         int difference = minuendYear - subtrahendYear;
93         if (minuendRem < subtrahendRem) {
94             difference--;
95         }
96         return difference;
97     }
98
99     //-----------------------------------------------------------------------
100 long getTotalMillisByYearMonth(int year, int month) {
101         return ((month - 1) * MILLIS_PER_MONTH);
102     }
103
104     //-----------------------------------------------------------------------
105 int getDayOfMonth(long millis) {
106         // optimised for fixed months
107 return (getDayOfYear(millis) - 1) % MONTH_LENGTH + 1;
108     }
109
110     //-----------------------------------------------------------------------
111 boolean isLeapYear(int year) {
112         return (year & 3) == 3;
113     }
114
115     //-----------------------------------------------------------------------
116 int getDaysInYearMonth(int year, int month) {
117         return (month != 13) ? MONTH_LENGTH : (isLeapYear(year) ? 6 : 5);
118     }
119
120     //-----------------------------------------------------------------------
121 int getDaysInMonthMax() {
122         return MONTH_LENGTH;
123     }
124
125     //-----------------------------------------------------------------------
126 int getDaysInMonthMax(int month) {
127         return (month != 13 ? MONTH_LENGTH : 6);
128     }
129
130     //-----------------------------------------------------------------------
131 int getMonthOfYear(long millis) {
132         return (getDayOfYear(millis) - 1) / MONTH_LENGTH + 1;
133     }
134
135     //-----------------------------------------------------------------------
136 int getMonthOfYear(long millis, int year) {
137         long monthZeroBased = (millis - getYearMillis(year)) / MILLIS_PER_MONTH;
138         return ((int) monthZeroBased) + 1;
139     }
140
141     //-----------------------------------------------------------------------
142 int getMaxMonth() {
143         return 13;
144     }
145
146     //-----------------------------------------------------------------------
147 long getAverageMillisPerYear() {
148         return MILLIS_PER_YEAR;
149     }
150
151     //-----------------------------------------------------------------------
152 long getAverageMillisPerYearDividedByTwo() {
153         return MILLIS_PER_YEAR / 2;
154     }
155
156     //-----------------------------------------------------------------------
157 long getAverageMillisPerMonth() {
158         return MILLIS_PER_MONTH;
159     }
160
161 }
162
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