001    /*
002     *  Copyright 2001-2010 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.convert.FromString;
019    import org.joda.convert.ToString;
020    import org.joda.time.base.BaseSingleFieldPeriod;
021    import org.joda.time.field.FieldUtils;
022    import org.joda.time.format.ISOPeriodFormat;
023    import org.joda.time.format.PeriodFormatter;
024    
025    /**
026     * An immutable time period representing a number of hours.
027     * <p>
028     * <code>Hours</code> is an immutable period that can only store hours.
029     * It does not store years, months or minutes for example. As such it is a
030     * type-safe way of representing a number of hours in an application.
031     * <p>
032     * The number of hours is set in the constructor, and may be queried using
033     * <code>getHours()</code>. Basic mathematical operations are provided -
034     * <code>plus()</code>, <code>minus()</code>, <code>multipliedBy()</code> and
035     * <code>dividedBy()</code>.
036     * <p>
037     * <code>Hours</code> is thread-safe and immutable.
038     *
039     * @author Stephen Colebourne
040     * @since 1.4
041     */
042    public final class Hours extends BaseSingleFieldPeriod {
043    
044        /** Constant representing zero hours. */
045        public static final Hours ZERO = new Hours(0);
046        /** Constant representing one hour. */
047        public static final Hours ONE = new Hours(1);
048        /** Constant representing two hours. */
049        public static final Hours TWO = new Hours(2);
050        /** Constant representing three hours. */
051        public static final Hours THREE = new Hours(3);
052        /** Constant representing four hours. */
053        public static final Hours FOUR = new Hours(4);
054        /** Constant representing five hours. */
055        public static final Hours FIVE = new Hours(5);
056        /** Constant representing six hours. */
057        public static final Hours SIX = new Hours(6);
058        /** Constant representing seven hours. */
059        public static final Hours SEVEN = new Hours(7);
060        /** Constant representing eight hours. */
061        public static final Hours EIGHT = new Hours(8);
062        /** Constant representing the maximum number of hours that can be stored in this object. */
063        public static final Hours MAX_VALUE = new Hours(Integer.MAX_VALUE);
064        /** Constant representing the minimum number of hours that can be stored in this object. */
065        public static final Hours MIN_VALUE = new Hours(Integer.MIN_VALUE);
066    
067        /** The paser to use for this class. */
068        private static final PeriodFormatter PARSER = ISOPeriodFormat.standard().withParseType(PeriodType.hours());
069        /** Serialization version. */
070        private static final long serialVersionUID = 87525275727380864L;
071    
072        //-----------------------------------------------------------------------
073        /**
074         * Obtains an instance of <code>Hours</code> that may be cached.
075         * <code>Hours</code> is immutable, so instances can be cached and shared.
076         * This factory method provides access to shared instances.
077         *
078         * @param hours  the number of hours to obtain an instance for
079         * @return the instance of Hours
080         */
081        public static Hours hours(int hours) {
082            switch (hours) {
083                case 0:
084                    return ZERO;
085                case 1:
086                    return ONE;
087                case 2:
088                    return TWO;
089                case 3:
090                    return THREE;
091                case 4:
092                    return FOUR;
093                case 5:
094                    return FIVE;
095                case 6:
096                    return SIX;
097                case 7:
098                    return SEVEN;
099                case 8:
100                    return EIGHT;
101                case Integer.MAX_VALUE:
102                    return MAX_VALUE;
103                case Integer.MIN_VALUE:
104                    return MIN_VALUE;
105                default:
106                    return new Hours(hours);
107            }
108        }
109    
110        //-----------------------------------------------------------------------
111        /**
112         * Creates a <code>Hours</code> representing the number of whole hours
113         * between the two specified datetimes.
114         *
115         * @param start  the start instant, must not be null
116         * @param end  the end instant, must not be null
117         * @return the period in hours
118         * @throws IllegalArgumentException if the instants are null or invalid
119         */
120        public static Hours hoursBetween(ReadableInstant start, ReadableInstant end) {
121            int amount = BaseSingleFieldPeriod.between(start, end, DurationFieldType.hours());
122            return Hours.hours(amount);
123        }
124    
125        /**
126         * Creates a <code>Hours</code> representing the number of whole hours
127         * between the two specified partial datetimes.
128         * <p>
129         * The two partials must contain the same fields, for example you can specify
130         * two <code>LocalTime</code> objects.
131         *
132         * @param start  the start partial date, must not be null
133         * @param end  the end partial date, must not be null
134         * @return the period in hours
135         * @throws IllegalArgumentException if the partials are null or invalid
136         */
137        public static Hours hoursBetween(ReadablePartial start, ReadablePartial end) {
138            if (start instanceof LocalTime && end instanceof LocalTime)   {
139                Chronology chrono = DateTimeUtils.getChronology(start.getChronology());
140                int hours = chrono.hours().getDifference(
141                        ((LocalTime) end).getLocalMillis(), ((LocalTime) start).getLocalMillis());
142                return Hours.hours(hours);
143            }
144            int amount = BaseSingleFieldPeriod.between(start, end, ZERO);
145            return Hours.hours(amount);
146        }
147    
148        /**
149         * Creates a <code>Hours</code> representing the number of whole hours
150         * in the specified interval.
151         *
152         * @param interval  the interval to extract hours from, null returns zero
153         * @return the period in hours
154         * @throws IllegalArgumentException if the partials are null or invalid
155         */
156        public static Hours hoursIn(ReadableInterval interval) {
157            if (interval == null)   {
158                return Hours.ZERO;
159            }
160            int amount = BaseSingleFieldPeriod.between(interval.getStart(), interval.getEnd(), DurationFieldType.hours());
161            return Hours.hours(amount);
162        }
163    
164        /**
165         * Creates a new <code>Hours</code> representing the number of complete
166         * standard length hours in the specified period.
167         * <p>
168         * This factory method converts all fields from the period to hours using standardised
169         * durations for each field. Only those fields which have a precise duration in
170         * the ISO UTC chronology can be converted.
171         * <ul>
172         * <li>One week consists of 7 days.
173         * <li>One day consists of 24 hours.
174         * <li>One hour consists of 60 minutes.
175         * <li>One minute consists of 60 seconds.
176         * <li>One second consists of 1000 milliseconds.
177         * </ul>
178         * Months and Years are imprecise and periods containing these values cannot be converted.
179         *
180         * @param period  the period to get the number of hours from, null returns zero
181         * @return the period in hours
182         * @throws IllegalArgumentException if the period contains imprecise duration values
183         */
184        public static Hours standardHoursIn(ReadablePeriod period) {
185            int amount = BaseSingleFieldPeriod.standardPeriodIn(period, DateTimeConstants.MILLIS_PER_HOUR);
186            return Hours.hours(amount);
187        }
188    
189        /**
190         * Creates a new <code>Hours</code> by parsing a string in the ISO8601 format 'PTnH'.
191         * <p>
192         * The parse will accept the full ISO syntax of PnYnMnWnDTnHnMnS however only the
193         * hours component may be non-zero. If any other component is non-zero, an exception
194         * will be thrown.
195         *
196         * @param periodStr  the period string, null returns zero
197         * @return the period in hours
198         * @throws IllegalArgumentException if the string format is invalid
199         */
200        @FromString
201        public static Hours parseHours(String periodStr) {
202            if (periodStr == null) {
203                return Hours.ZERO;
204            }
205            Period p = PARSER.parsePeriod(periodStr);
206            return Hours.hours(p.getHours());
207        }
208    
209        //-----------------------------------------------------------------------
210        /**
211         * Creates a new instance representing a number of hours.
212         * You should consider using the factory method {@link #hours(int)}
213         * instead of the constructor.
214         *
215         * @param hours  the number of hours to represent
216         */
217        private Hours(int hours) {
218            super(hours);
219        }
220    
221        /**
222         * Resolves singletons.
223         * 
224         * @return the singleton instance
225         */
226        private Object readResolve() {
227            return Hours.hours(getValue());
228        }
229    
230        //-----------------------------------------------------------------------
231        /**
232         * Gets the duration field type, which is <code>hours</code>.
233         *
234         * @return the period type
235         */
236        public DurationFieldType getFieldType() {
237            return DurationFieldType.hours();
238        }
239    
240        /**
241         * Gets the period type, which is <code>hours</code>.
242         *
243         * @return the period type
244         */
245        public PeriodType getPeriodType() {
246            return PeriodType.hours();
247        }
248    
249        //-----------------------------------------------------------------------
250        /**
251         * Converts this period in hours to a period in weeks assuming a
252         * 7 day week and 24 hour day.
253         * <p>
254         * This method allows you to convert between different types of period.
255         * However to achieve this it makes the assumption that all weeks are 7 days
256         * long and all days are 24 hours long.
257         * This is not true when daylight savings time is considered, and may also
258         * not be true for some unusual chronologies. However, it is included as it
259         * is a useful operation for many applications and business rules.
260         * 
261         * @return a period representing the number of whole weeks for this number of hours
262         */
263        public Weeks toStandardWeeks() {
264            return Weeks.weeks(getValue() / DateTimeConstants.HOURS_PER_WEEK);
265        }
266    
267        /**
268         * Converts this period in hours to a period in days assuming a
269         * 24 hour day.
270         * <p>
271         * This method allows you to convert between different types of period.
272         * However to achieve this it makes the assumption that all days are 24 hours long.
273         * This is not true when daylight savings time is considered, and may also
274         * not be true for some unusual chronologies. However, it is included as it
275         * is a useful operation for many applications and business rules.
276         * 
277         * @return a period representing the number of whole days for this number of hours
278         */
279        public Days toStandardDays() {
280            return Days.days(getValue() / DateTimeConstants.HOURS_PER_DAY);
281        }
282    
283        /**
284         * Converts this period in hours to a period in minutes assuming a
285         * 60 minute hour.
286         * <p>
287         * This method allows you to convert between different types of period.
288         * However to achieve this it makes the assumption that all hours are 60 minutes long.
289         * This may not 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 minutes for this number of hours
293         * @throws ArithmeticException if the number of minutes is too large to be represented
294         */
295        public Minutes toStandardMinutes() {
296            return Minutes.minutes(FieldUtils.safeMultiply(getValue(), DateTimeConstants.MINUTES_PER_HOUR));
297        }
298    
299        /**
300         * Converts this period in hours to a period in seconds assuming a
301         * 60 minute hour and 60 second minute.
302         * <p>
303         * This method allows you to convert between different types of period.
304         * However to achieve this it makes the assumption that all hours are
305         * 60 minutes long and all minutes are 60 seconds long.
306         * This may not be true for some unusual chronologies. However, it is included
307         * as it is a useful operation for many applications and business rules.
308         * 
309         * @return a period representing the number of seconds for this number of hours
310         * @throws ArithmeticException if the number of seconds is too large to be represented
311         */
312        public Seconds toStandardSeconds() {
313            return Seconds.seconds(FieldUtils.safeMultiply(getValue(), DateTimeConstants.SECONDS_PER_HOUR));
314        }
315    
316        //-----------------------------------------------------------------------
317        /**
318         * Converts this period in hours to a duration in milliseconds assuming a
319         * 60 minute hour and 60 second minute.
320         * <p>
321         * This method allows you to convert from a period to a duration.
322         * However to achieve this it makes the assumption that all hours are
323         * 60 minutes and all minutes are 60 seconds. This might not be true for an
324         * unusual chronology, for example one that takes leap seconds into account.
325         * However, the method is included as it is a useful operation for many
326         * applications and business rules.
327         *
328         * @return a duration equivalent to this number of hours
329         */
330        public Duration toStandardDuration() {
331            long hours = getValue();  // assign to a long
332            return new Duration(hours * DateTimeConstants.MILLIS_PER_HOUR);
333        }
334    
335        //-----------------------------------------------------------------------
336        /**
337         * Gets the number of hours that this period represents.
338         *
339         * @return the number of hours in the period
340         */
341        public int getHours() {
342            return getValue();
343        }
344    
345        //-----------------------------------------------------------------------
346        /**
347         * Returns a new instance with the specified number of hours added.
348         * <p>
349         * This instance is immutable and unaffected by this method call.
350         *
351         * @param hours  the amount of hours to add, may be negative
352         * @return the new period plus the specified number of hours
353         * @throws ArithmeticException if the result overflows an int
354         */
355        public Hours plus(int hours) {
356            if (hours == 0) {
357                return this;
358            }
359            return Hours.hours(FieldUtils.safeAdd(getValue(), hours));
360        }
361    
362        /**
363         * Returns a new instance with the specified number of hours added.
364         * <p>
365         * This instance is immutable and unaffected by this method call.
366         *
367         * @param hours  the amount of hours to add, may be negative, null means zero
368         * @return the new period plus the specified number of hours
369         * @throws ArithmeticException if the result overflows an int
370         */
371        public Hours plus(Hours hours) {
372            if (hours == null) {
373                return this;
374            }
375            return plus(hours.getValue());
376        }
377    
378        //-----------------------------------------------------------------------
379        /**
380         * Returns a new instance with the specified number of hours taken away.
381         * <p>
382         * This instance is immutable and unaffected by this method call.
383         *
384         * @param hours  the amount of hours to take away, may be negative
385         * @return the new period minus the specified number of hours
386         * @throws ArithmeticException if the result overflows an int
387         */
388        public Hours minus(int hours) {
389            return plus(FieldUtils.safeNegate(hours));
390        }
391    
392        /**
393         * Returns a new instance with the specified number of hours taken away.
394         * <p>
395         * This instance is immutable and unaffected by this method call.
396         *
397         * @param hours  the amount of hours to take away, may be negative, null means zero
398         * @return the new period minus the specified number of hours
399         * @throws ArithmeticException if the result overflows an int
400         */
401        public Hours minus(Hours hours) {
402            if (hours == null) {
403                return this;
404            }
405            return minus(hours.getValue());
406        }
407    
408        //-----------------------------------------------------------------------
409        /**
410         * Returns a new instance with the hours multiplied by the specified scalar.
411         * <p>
412         * This instance is immutable and unaffected by this method call.
413         *
414         * @param scalar  the amount to multiply by, may be negative
415         * @return the new period multiplied by the specified scalar
416         * @throws ArithmeticException if the result overflows an int
417         */
418        public Hours multipliedBy(int scalar) {
419            return Hours.hours(FieldUtils.safeMultiply(getValue(), scalar));
420        }
421    
422        /**
423         * Returns a new instance with the hours divided by the specified divisor.
424         * The calculation uses integer division, thus 3 divided by 2 is 1.
425         * <p>
426         * This instance is immutable and unaffected by this method call.
427         *
428         * @param divisor  the amount to divide by, may be negative
429         * @return the new period divided by the specified divisor
430         * @throws ArithmeticException if the divisor is zero
431         */
432        public Hours dividedBy(int divisor) {
433            if (divisor == 1) {
434                return this;
435            }
436            return Hours.hours(getValue() / divisor);
437        }
438    
439        //-----------------------------------------------------------------------
440        /**
441         * Returns a new instance with the hours value negated.
442         *
443         * @return the new period with a negated value
444         * @throws ArithmeticException if the result overflows an int
445         */
446        public Hours negated() {
447            return Hours.hours(FieldUtils.safeNegate(getValue()));
448        }
449    
450        //-----------------------------------------------------------------------
451        /**
452         * Is this hours instance greater than the specified number of hours.
453         *
454         * @param other  the other period, null means zero
455         * @return true if this hours instance is greater than the specified one
456         */
457        public boolean isGreaterThan(Hours other) {
458            if (other == null) {
459                return getValue() > 0;
460            }
461            return getValue() > other.getValue();
462        }
463    
464        /**
465         * Is this hours instance less than the specified number of hours.
466         *
467         * @param other  the other period, null means zero
468         * @return true if this hours instance is less than the specified one
469         */
470        public boolean isLessThan(Hours other) {
471            if (other == null) {
472                return getValue() < 0;
473            }
474            return getValue() < other.getValue();
475        }
476    
477        //-----------------------------------------------------------------------
478        /**
479         * Gets this instance as a String in the ISO8601 duration format.
480         * <p>
481         * For example, "PT4H" represents 4 hours.
482         *
483         * @return the value as an ISO8601 string
484         */
485        @ToString
486        public String toString() {
487            return "PT" + String.valueOf(getValue()) + "H";
488        }
489    
490    }