001    /*
002     *  Copyright 2001-2006 Stephen Colebourne
003     *
004     *  Licensed under the Apache License, Version 2.0 (the "License");
005     *  you may not use this file except in compliance with the License.
006     *  You may obtain a copy of the License at
007     *
008     *      http://www.apache.org/licenses/LICENSE-2.0
009     *
010     *  Unless required by applicable law or agreed to in writing, software
011     *  distributed under the License is distributed on an "AS IS" BASIS,
012     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     *  See the License for the specific language governing permissions and
014     *  limitations under the License.
015     */
016    package org.joda.time;
017    
018    import org.joda.time.base.BaseSingleFieldPeriod;
019    import org.joda.time.field.FieldUtils;
020    import org.joda.time.format.ISOPeriodFormat;
021    import org.joda.time.format.PeriodFormatter;
022    
023    /**
024     * An immutable time period representing a number of weeks.
025     * <p>
026     * <code>Weeks</code> is an immutable period that can only store weeks.
027     * It does not store years, months or hours for example. As such it is a
028     * type-safe way of representing a number of weeks in an application.
029     * <p>
030     * The number of weeks is set in the constructor, and may be queried using
031     * <code>getWeeks()</code>. Basic mathematical operations are provided -
032     * <code>plus()</code>, <code>minus()</code>, <code>multipliedBy()</code> and
033     * <code>dividedBy()</code>.
034     * <p>
035     * <code>Weeks</code> is thread-safe and immutable.
036     *
037     * @author Stephen Colebourne
038     * @since 1.4
039     */
040    public final class Weeks extends BaseSingleFieldPeriod {
041    
042        /** Constant representing zero weeks. */
043        public static final Weeks ZERO = new Weeks(0);
044        /** Constant representing one week. */
045        public static final Weeks ONE = new Weeks(1);
046        /** Constant representing two weeks. */
047        public static final Weeks TWO = new Weeks(2);
048        /** Constant representing three weeks. */
049        public static final Weeks THREE = new Weeks(3);
050        /** Constant representing the maximum number of weeks that can be stored in this object. */
051        public static final Weeks MAX_VALUE = new Weeks(Integer.MAX_VALUE);
052        /** Constant representing the minimum number of weeks that can be stored in this object. */
053        public static final Weeks MIN_VALUE = new Weeks(Integer.MIN_VALUE);
054    
055        /** The paser to use for this class. */
056        private static final PeriodFormatter PARSER = ISOPeriodFormat.standard().withParseType(PeriodType.weeks());
057        /** Serialization version. */
058        private static final long serialVersionUID = 87525275727380866L;
059    
060        //-----------------------------------------------------------------------
061        /**
062         * Obtains an instance of <code>Weeks</code> that may be cached.
063         * <code>Weeks</code> is immutable, so instances can be cached and shared.
064         * This factory method provides access to shared instances.
065         *
066         * @param weeks  the number of weeks to obtain an instance for
067         * @return the instance of Weeks
068         */
069        public static Weeks weeks(int weeks) {
070            switch (weeks) {
071                case 0:
072                    return ZERO;
073                case 1:
074                    return ONE;
075                case 2:
076                    return TWO;
077                case 3:
078                    return THREE;
079                case Integer.MAX_VALUE:
080                    return MAX_VALUE;
081                case Integer.MIN_VALUE:
082                    return MIN_VALUE;
083                default:
084                    return new Weeks(weeks);
085            }
086        }
087    
088        //-----------------------------------------------------------------------
089        /**
090         * Creates a <code>Weeks</code> representing the number of whole weeks
091         * between the two specified datetimes.
092         *
093         * @param start  the start instant, must not be null
094         * @param end  the end instant, must not be null
095         * @return the period in weeks
096         * @throws IllegalArgumentException if the instants are null or invalid
097         */
098        public static Weeks weeksBetween(ReadableInstant start, ReadableInstant end) {
099            int amount = BaseSingleFieldPeriod.between(start, end, DurationFieldType.weeks());
100            return Weeks.weeks(amount);
101        }
102    
103        /**
104         * Creates a <code>Weeks</code> representing the number of whole weeks
105         * between the two specified partial datetimes.
106         * <p>
107         * The two partials must contain the same fields, for example you can specify
108         * two <code>LocalDate</code> objects.
109         *
110         * @param start  the start partial date, must not be null
111         * @param end  the end partial date, must not be null
112         * @return the period in weeks
113         * @throws IllegalArgumentException if the partials are null or invalid
114         */
115        public static Weeks weeksBetween(ReadablePartial start, ReadablePartial end) {
116            if (start instanceof LocalDate && end instanceof LocalDate)   {
117                Chronology chrono = DateTimeUtils.getChronology(start.getChronology());
118                int weeks = chrono.weeks().getDifference(
119                        ((LocalDate) end).getLocalMillis(), ((LocalDate) start).getLocalMillis());
120                return Weeks.weeks(weeks);
121            }
122            int amount = BaseSingleFieldPeriod.between(start, end, ZERO);
123            return Weeks.weeks(amount);
124        }
125    
126        /**
127         * Creates a <code>Weeks</code> representing the number of whole weeks
128         * in the specified interval.
129         *
130         * @param interval  the interval to extract weeks from, null returns zero
131         * @return the period in weeks
132         * @throws IllegalArgumentException if the partials are null or invalid
133         */
134        public static Weeks weeksIn(ReadableInterval interval) {
135            if (interval == null)   {
136                return Weeks.ZERO;
137            }
138            int amount = BaseSingleFieldPeriod.between(interval.getStart(), interval.getEnd(), DurationFieldType.weeks());
139            return Weeks.weeks(amount);
140        }
141    
142        /**
143         * Creates a new <code>Weeks</code> representing the number of complete
144         * standard length weeks in the specified period.
145         * <p>
146         * This factory method converts all fields from the period to hours using standardised
147         * durations for each field. Only those fields which have a precise duration in
148         * the ISO UTC chronology can be converted.
149         * <ul>
150         * <li>One week consists of 7 days.
151         * <li>One day consists of 24 hours.
152         * <li>One hour consists of 60 minutes.
153         * <li>One minute consists of 60 weeks.
154         * <li>One second consists of 1000 milliseconds.
155         * </ul>
156         * Months and Years are imprecise and periods containing these values cannot be converted.
157         *
158         * @param period  the period to get the number of hours from, null returns zero
159         * @return the period in weeks
160         * @throws IllegalArgumentException if the period contains imprecise duration values
161         */
162        public static Weeks standardWeeksIn(ReadablePeriod period) {
163            int amount = BaseSingleFieldPeriod.standardPeriodIn(period, DateTimeConstants.MILLIS_PER_WEEK);
164            return Weeks.weeks(amount);
165        }
166    
167        /**
168         * Creates a new <code>Weeks</code> by parsing a string in the ISO8601 format 'PnW'.
169         * <p>
170         * The parse will accept the full ISO syntax of PnYnMnWnDTnHnMnS however only the
171         * weeks component may be non-zero. If any other component is non-zero, an exception
172         * will be thrown.
173         *
174         * @param periodStr  the period string, null returns zero
175         * @return the period in weeks
176         * @throws IllegalArgumentException if the string format is invalid
177         */
178        public static Weeks parseWeeks(String periodStr) {
179            if (periodStr == null) {
180                return Weeks.ZERO;
181            }
182            Period p = PARSER.parsePeriod(periodStr);
183            return Weeks.weeks(p.getWeeks());
184        }
185    
186        //-----------------------------------------------------------------------
187        /**
188         * Creates a new instance representing a number of weeks.
189         * You should consider using the factory method {@link #weeks(int)}
190         * instead of the constructor.
191         *
192         * @param weeks  the number of weeks to represent
193         */
194        private Weeks(int weeks) {
195            super(weeks);
196        }
197    
198        /**
199         * Resolves singletons.
200         * 
201         * @return the singleton instance
202         */
203        private Object readResolve() {
204            return Weeks.weeks(getValue());
205        }
206    
207        //-----------------------------------------------------------------------
208        /**
209         * Gets the duration field type, which is <code>weeks</code>.
210         *
211         * @return the period type
212         */
213        public DurationFieldType getFieldType() {
214            return DurationFieldType.weeks();
215        }
216    
217        /**
218         * Gets the period type, which is <code>weeks</code>.
219         *
220         * @return the period type
221         */
222        public PeriodType getPeriodType() {
223            return PeriodType.weeks();
224        }
225    
226        //-----------------------------------------------------------------------
227        /**
228         * Converts this period in weeks to a period in days assuming a
229         * 7 day week.
230         * <p>
231         * This method allows you to convert between different types of period.
232         * However to achieve this it makes the assumption that all weeks are
233         * 7 days long.
234         * This may not be true for some unusual chronologies. However, it is included
235         * as it is a useful operation for many applications and business rules.
236         * 
237         * @return a period representing the number of days for this number of weeks
238         * @throws ArithmeticException if the number of days is too large to be represented
239         */
240        public Days toStandardDays() {
241            return Days.days(FieldUtils.safeMultiply(getValue(), DateTimeConstants.DAYS_PER_WEEK));
242        }
243    
244        /**
245         * Converts this period in weeks to a period in hours assuming a
246         * 7 day week and 24 hour day.
247         * <p>
248         * This method allows you to convert between different types of period.
249         * However to achieve this it makes the assumption that all weeks are
250         * 7 days long and all days are 24 hours long.
251         * This is not true when daylight savings is considered and may also not
252         * be true for some unusual chronologies. However, it is included
253         * as it is a useful operation for many applications and business rules.
254         * 
255         * @return a period representing the number of hours for this number of weeks
256         * @throws ArithmeticException if the number of hours is too large to be represented
257         */
258        public Hours toStandardHours() {
259            return Hours.hours(FieldUtils.safeMultiply(getValue(), DateTimeConstants.HOURS_PER_WEEK));
260        }
261    
262        /**
263         * Converts this period in weeks to a period in minutes assuming a
264         * 7 day week, 24 hour day and 60 minute hour.
265         * <p>
266         * This method allows you to convert between different types of period.
267         * However to achieve this it makes the assumption that all weeks are
268         * 7 days long, all days are 24 hours long and all hours are 60 minutes long.
269         * This is not true when daylight savings is considered and may also not
270         * be true for some unusual chronologies. However, it is included
271         * as it is a useful operation for many applications and business rules.
272         * 
273         * @return a period representing the number of minutes for this number of weeks
274         * @throws ArithmeticException if the number of minutes is too large to be represented
275         */
276        public Minutes toStandardMinutes() {
277            return Minutes.minutes(FieldUtils.safeMultiply(getValue(), DateTimeConstants.MINUTES_PER_WEEK));
278        }
279    
280        /**
281         * Converts this period in weeks to a period in seconds assuming a
282         * 7 day week, 24 hour day, 60 minute hour and 60 second minute.
283         * <p>
284         * This method allows you to convert between different types of period.
285         * However to achieve this it makes the assumption that all weeks are
286         * 7 days long, all days are 24 hours long, all hours are 60 minutes long
287         * and all minutes are 60 seconds long.
288         * This is not true when daylight savings is considered and may also not
289         * be true for some unusual chronologies. However, it is included
290         * as it is a useful operation for many applications and business rules.
291         * 
292         * @return a period representing the number of seconds for this number of weeks
293         * @throws ArithmeticException if the number of seconds is too large to be represented
294         */
295        public Seconds toStandardSeconds() {
296            return Seconds.seconds(FieldUtils.safeMultiply(getValue(), DateTimeConstants.SECONDS_PER_WEEK));
297        }
298    
299        //-----------------------------------------------------------------------
300        /**
301         * Converts this period in weeks to a duration in milliweeks assuming a
302         * 7 day week, 24 hour day, 60 minute hour and 60 second minute.
303         * <p>
304         * This method allows you to convert from a period to a duration.
305         * However to achieve this it makes the assumption that all weeks are
306         * 7 days long, all days are 24 hours long, all hours are 60 minutes long
307         * and all minutes are 60 seconds long.
308         * This is not true when daylight savings time is considered, and may also
309         * not be true for some unusual chronologies. However, it is included as it
310         * is a useful operation for many applications and business rules.
311         * 
312         * @return a duration equivalent to this number of weeks
313         */
314        public Duration toStandardDuration() {
315            long weeks = getValue();  // assign to a long
316            return new Duration(weeks * DateTimeConstants.MILLIS_PER_WEEK);
317        }
318    
319        //-----------------------------------------------------------------------
320        /**
321         * Gets the number of weeks that this period represents.
322         *
323         * @return the number of weeks in the period
324         */
325        public int getWeeks() {
326            return getValue();
327        }
328    
329        //-----------------------------------------------------------------------
330        /**
331         * Returns a new instance with the specified number of weeks added.
332         * <p>
333         * This instance is immutable and unaffected by this method call.
334         *
335         * @param weeks  the amount of weeks to add, may be negative
336         * @return the new period plus the specified number of weeks
337         * @throws ArithmeticException if the result overflows an int
338         */
339        public Weeks plus(int weeks) {
340            if (weeks == 0) {
341                return this;
342            }
343            return Weeks.weeks(FieldUtils.safeAdd(getValue(), weeks));
344        }
345    
346        /**
347         * Returns a new instance with the specified number of weeks added.
348         * <p>
349         * This instance is immutable and unaffected by this method call.
350         *
351         * @param weeks  the amount of weeks to add, may be negative, null means zero
352         * @return the new period plus the specified number of weeks
353         * @throws ArithmeticException if the result overflows an int
354         */
355        public Weeks plus(Weeks weeks) {
356            if (weeks == null) {
357                return this;
358            }
359            return plus(weeks.getValue());
360        }
361    
362        //-----------------------------------------------------------------------
363        /**
364         * Returns a new instance with the specified number of weeks taken away.
365         * <p>
366         * This instance is immutable and unaffected by this method call.
367         *
368         * @param weeks  the amount of weeks to take away, may be negative
369         * @return the new period minus the specified number of weeks
370         * @throws ArithmeticException if the result overflows an int
371         */
372        public Weeks minus(int weeks) {
373            return plus(FieldUtils.safeNegate(weeks));
374        }
375    
376        /**
377         * Returns a new instance with the specified number of weeks taken away.
378         * <p>
379         * This instance is immutable and unaffected by this method call.
380         *
381         * @param weeks  the amount of weeks to take away, may be negative, null means zero
382         * @return the new period minus the specified number of weeks
383         * @throws ArithmeticException if the result overflows an int
384         */
385        public Weeks minus(Weeks weeks) {
386            if (weeks == null) {
387                return this;
388            }
389            return minus(weeks.getValue());
390        }
391    
392        //-----------------------------------------------------------------------
393        /**
394         * Returns a new instance with the weeks multiplied by the specified scalar.
395         * <p>
396         * This instance is immutable and unaffected by this method call.
397         *
398         * @param scalar  the amount to multiply by, may be negative
399         * @return the new period multiplied by the specified scalar
400         * @throws ArithmeticException if the result overflows an int
401         */
402        public Weeks multipliedBy(int scalar) {
403            return Weeks.weeks(FieldUtils.safeMultiply(getValue(), scalar));
404        }
405    
406        /**
407         * Returns a new instance with the weeks divided by the specified divisor.
408         * The calculation uses integer division, thus 3 divided by 2 is 1.
409         * <p>
410         * This instance is immutable and unaffected by this method call.
411         *
412         * @param divisor  the amount to divide by, may be negative
413         * @return the new period divided by the specified divisor
414         * @throws ArithmeticException if the divisor is zero
415         */
416        public Weeks dividedBy(int divisor) {
417            if (divisor == 1) {
418                return this;
419            }
420            return Weeks.weeks(getValue() / divisor);
421        }
422    
423        //-----------------------------------------------------------------------
424        /**
425         * Returns a new instance with the weeks value negated.
426         *
427         * @return the new period with a negated value
428         * @throws ArithmeticException if the result overflows an int
429         */
430        public Weeks negated() {
431            return Weeks.weeks(FieldUtils.safeNegate(getValue()));
432        }
433    
434        //-----------------------------------------------------------------------
435        /**
436         * Is this weeks instance greater than the specified number of weeks.
437         *
438         * @param other  the other period, null means zero
439         * @return true if this weeks instance is greater than the specified one
440         */
441        public boolean isGreaterThan(Weeks other) {
442            if (other == null) {
443                return getValue() > 0;
444            }
445            return getValue() > other.getValue();
446        }
447    
448        /**
449         * Is this weeks instance less than the specified number of weeks.
450         *
451         * @param other  the other period, null means zero
452         * @return true if this weeks instance is less than the specified one
453         */
454        public boolean isLessThan(Weeks other) {
455            if (other == null) {
456                return getValue() < 0;
457            }
458            return getValue() < other.getValue();
459        }
460    
461        //-----------------------------------------------------------------------
462        /**
463         * Gets this instance as a String in the ISO8601 duration format.
464         * <p>
465         * For example, "P4W" represents 4 weeks.
466         *
467         * @return the value as an ISO8601 string
468         */
469        public String toString() {
470            return "P" + String.valueOf(getValue()) + "W";
471        }
472    
473    }