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 hours.
025     * <p>
026     * <code>Hours</code> is an immutable period that can only store hours.
027     * It does not store years, months or minutes for example. As such it is a
028     * type-safe way of representing a number of hours in an application.
029     * <p>
030     * The number of hours is set in the constructor, and may be queried using
031     * <code>getHours()</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>Hours</code> is thread-safe and immutable.
036     *
037     * @author Stephen Colebourne
038     * @since 1.4
039     */
040    public final class Hours extends BaseSingleFieldPeriod {
041    
042        /** Constant representing zero hours. */
043        public static final Hours ZERO = new Hours(0);
044        /** Constant representing one hour. */
045        public static final Hours ONE = new Hours(1);
046        /** Constant representing two hours. */
047        public static final Hours TWO = new Hours(2);
048        /** Constant representing three hours. */
049        public static final Hours THREE = new Hours(3);
050        /** Constant representing four hours. */
051        public static final Hours FOUR = new Hours(4);
052        /** Constant representing five hours. */
053        public static final Hours FIVE = new Hours(5);
054        /** Constant representing six hours. */
055        public static final Hours SIX = new Hours(6);
056        /** Constant representing seven hours. */
057        public static final Hours SEVEN = new Hours(7);
058        /** Constant representing eight hours. */
059        public static final Hours EIGHT = new Hours(8);
060        /** Constant representing the maximum number of hours that can be stored in this object. */
061        public static final Hours MAX_VALUE = new Hours(Integer.MAX_VALUE);
062        /** Constant representing the minimum number of hours that can be stored in this object. */
063        public static final Hours MIN_VALUE = new Hours(Integer.MIN_VALUE);
064    
065        /** The paser to use for this class. */
066        private static final PeriodFormatter PARSER = ISOPeriodFormat.standard().withParseType(PeriodType.hours());
067        /** Serialization version. */
068        private static final long serialVersionUID = 87525275727380864L;
069    
070        //-----------------------------------------------------------------------
071        /**
072         * Obtains an instance of <code>Hours</code> that may be cached.
073         * <code>Hours</code> is immutable, so instances can be cached and shared.
074         * This factory method provides access to shared instances.
075         *
076         * @param hours  the number of hours to obtain an instance for
077         * @return the instance of Hours
078         */
079        public static Hours hours(int hours) {
080            switch (hours) {
081                case 0:
082                    return ZERO;
083                case 1:
084                    return ONE;
085                case 2:
086                    return TWO;
087                case 3:
088                    return THREE;
089                case 4:
090                    return FOUR;
091                case 5:
092                    return FIVE;
093                case 6:
094                    return SIX;
095                case 7:
096                    return SEVEN;
097                case 8:
098                    return EIGHT;
099                case Integer.MAX_VALUE:
100                    return MAX_VALUE;
101                case Integer.MIN_VALUE:
102                    return MIN_VALUE;
103                default:
104                    return new Hours(hours);
105            }
106        }
107    
108        //-----------------------------------------------------------------------
109        /**
110         * Creates a <code>Hours</code> representing the number of whole hours
111         * between the two specified datetimes.
112         *
113         * @param start  the start instant, must not be null
114         * @param end  the end instant, must not be null
115         * @return the period in hours
116         * @throws IllegalArgumentException if the instants are null or invalid
117         */
118        public static Hours hoursBetween(ReadableInstant start, ReadableInstant end) {
119            int amount = BaseSingleFieldPeriod.between(start, end, DurationFieldType.hours());
120            return Hours.hours(amount);
121        }
122    
123        /**
124         * Creates a <code>Hours</code> representing the number of whole hours
125         * between the two specified partial datetimes.
126         * <p>
127         * The two partials must contain the same fields, for example you can specify
128         * two <code>LocalTime</code> objects.
129         *
130         * @param start  the start partial date, must not be null
131         * @param end  the end partial date, must not be null
132         * @return the period in hours
133         * @throws IllegalArgumentException if the partials are null or invalid
134         */
135        public static Hours hoursBetween(ReadablePartial start, ReadablePartial end) {
136            if (start instanceof LocalTime && end instanceof LocalTime)   {
137                Chronology chrono = DateTimeUtils.getChronology(start.getChronology());
138                int hours = chrono.hours().getDifference(
139                        ((LocalTime) end).getLocalMillis(), ((LocalTime) start).getLocalMillis());
140                return Hours.hours(hours);
141            }
142            int amount = BaseSingleFieldPeriod.between(start, end, ZERO);
143            return Hours.hours(amount);
144        }
145    
146        /**
147         * Creates a <code>Hours</code> representing the number of whole hours
148         * in the specified interval.
149         *
150         * @param interval  the interval to extract hours from, null returns zero
151         * @return the period in hours
152         * @throws IllegalArgumentException if the partials are null or invalid
153         */
154        public static Hours hoursIn(ReadableInterval interval) {
155            if (interval == null)   {
156                return Hours.ZERO;
157            }
158            int amount = BaseSingleFieldPeriod.between(interval.getStart(), interval.getEnd(), DurationFieldType.hours());
159            return Hours.hours(amount);
160        }
161    
162        /**
163         * Creates a new <code>Hours</code> representing the number of complete
164         * standard length hours in the specified period.
165         * <p>
166         * This factory method converts all fields from the period to hours using standardised
167         * durations for each field. Only those fields which have a precise duration in
168         * the ISO UTC chronology can be converted.
169         * <ul>
170         * <li>One week consists of 7 days.
171         * <li>One day consists of 24 hours.
172         * <li>One hour consists of 60 minutes.
173         * <li>One minute consists of 60 seconds.
174         * <li>One second consists of 1000 milliseconds.
175         * </ul>
176         * Months and Years are imprecise and periods containing these values cannot be converted.
177         *
178         * @param period  the period to get the number of hours from, null returns zero
179         * @return the period in hours
180         * @throws IllegalArgumentException if the period contains imprecise duration values
181         */
182        public static Hours standardHoursIn(ReadablePeriod period) {
183            int amount = BaseSingleFieldPeriod.standardPeriodIn(period, DateTimeConstants.MILLIS_PER_HOUR);
184            return Hours.hours(amount);
185        }
186    
187        /**
188         * Creates a new <code>Hours</code> by parsing a string in the ISO8601 format 'PTnH'.
189         * <p>
190         * The parse will accept the full ISO syntax of PnYnMnWnDTnHnMnS however only the
191         * hours component may be non-zero. If any other component is non-zero, an exception
192         * will be thrown.
193         *
194         * @param periodStr  the period string, null returns zero
195         * @return the period in hours
196         * @throws IllegalArgumentException if the string format is invalid
197         */
198        public static Hours parseHours(String periodStr) {
199            if (periodStr == null) {
200                return Hours.ZERO;
201            }
202            Period p = PARSER.parsePeriod(periodStr);
203            return Hours.hours(p.getHours());
204        }
205    
206        //-----------------------------------------------------------------------
207        /**
208         * Creates a new instance representing a number of hours.
209         * You should consider using the factory method {@link #hours(int)}
210         * instead of the constructor.
211         *
212         * @param hours  the number of hours to represent
213         */
214        private Hours(int hours) {
215            super(hours);
216        }
217    
218        /**
219         * Resolves singletons.
220         * 
221         * @return the singleton instance
222         */
223        private Object readResolve() {
224            return Hours.hours(getValue());
225        }
226    
227        //-----------------------------------------------------------------------
228        /**
229         * Gets the duration field type, which is <code>hours</code>.
230         *
231         * @return the period type
232         */
233        public DurationFieldType getFieldType() {
234            return DurationFieldType.hours();
235        }
236    
237        /**
238         * Gets the period type, which is <code>hours</code>.
239         *
240         * @return the period type
241         */
242        public PeriodType getPeriodType() {
243            return PeriodType.hours();
244        }
245    
246        //-----------------------------------------------------------------------
247        /**
248         * Converts this period in hours to a period in weeks assuming a
249         * 7 day week and 24 hour day.
250         * <p>
251         * This method allows you to convert between different types of period.
252         * However to achieve this it makes the assumption that all weeks are 7 days
253         * long and all days are 24 hours long.
254         * This is not true when daylight savings time is considered, and may also
255         * not be true for some unusual chronologies. However, it is included as it
256         * is a useful operation for many applications and business rules.
257         * 
258         * @return a period representing the number of whole weeks for this number of hours
259         */
260        public Weeks toStandardWeeks() {
261            return Weeks.weeks(getValue() / DateTimeConstants.HOURS_PER_WEEK);
262        }
263    
264        /**
265         * Converts this period in hours to a period in days assuming a
266         * 24 hour day.
267         * <p>
268         * This method allows you to convert between different types of period.
269         * However to achieve this it makes the assumption that all days are 24 hours long.
270         * This is not true when daylight savings time is considered, and may also
271         * not be true for some unusual chronologies. However, it is included as it
272         * is a useful operation for many applications and business rules.
273         * 
274         * @return a period representing the number of whole days for this number of hours
275         */
276        public Days toStandardDays() {
277            return Days.days(getValue() / DateTimeConstants.HOURS_PER_DAY);
278        }
279    
280        /**
281         * Converts this period in hours to a period in minutes assuming a
282         * 60 minute hour.
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 hours are 60 minutes long.
286         * This may not be true for some unusual chronologies. However, it is included
287         * as it is a useful operation for many applications and business rules.
288         * 
289         * @return a period representing the number of minutes for this number of hours
290         * @throws ArithmeticException if the number of minutes is too large to be represented
291         */
292        public Minutes toStandardMinutes() {
293            return Minutes.minutes(FieldUtils.safeMultiply(getValue(), DateTimeConstants.MINUTES_PER_HOUR));
294        }
295    
296        /**
297         * Converts this period in hours to a period in seconds assuming a
298         * 60 minute hour and 60 second minute.
299         * <p>
300         * This method allows you to convert between different types of period.
301         * However to achieve this it makes the assumption that all hours are
302         * 60 minutes long and all minutes are 60 seconds long.
303         * This may not be true for some unusual chronologies. However, it is included
304         * as it is a useful operation for many applications and business rules.
305         * 
306         * @return a period representing the number of seconds for this number of hours
307         * @throws ArithmeticException if the number of seconds is too large to be represented
308         */
309        public Seconds toStandardSeconds() {
310            return Seconds.seconds(FieldUtils.safeMultiply(getValue(), DateTimeConstants.SECONDS_PER_HOUR));
311        }
312    
313        //-----------------------------------------------------------------------
314        /**
315         * Converts this period in hours to a duration in milliseconds assuming a
316         * 60 minute hour and 60 second minute.
317         * <p>
318         * This method allows you to convert from a period to a duration.
319         * However to achieve this it makes the assumption that all hours are
320         * 60 minutes and all minutes are 60 seconds. This might not be true for an
321         * unusual chronology, for example one that takes leap seconds into account.
322         * However, the method is included as it is a useful operation for many
323         * applications and business rules.
324         *
325         * @return a duration equivalent to this number of hours
326         */
327        public Duration toStandardDuration() {
328            long hours = getValue();  // assign to a long
329            return new Duration(hours * DateTimeConstants.MILLIS_PER_HOUR);
330        }
331    
332        //-----------------------------------------------------------------------
333        /**
334         * Gets the number of hours that this period represents.
335         *
336         * @return the number of hours in the period
337         */
338        public int getHours() {
339            return getValue();
340        }
341    
342        //-----------------------------------------------------------------------
343        /**
344         * Returns a new instance with the specified number of hours added.
345         * <p>
346         * This instance is immutable and unaffected by this method call.
347         *
348         * @param hours  the amount of hours to add, may be negative
349         * @return the new period plus the specified number of hours
350         * @throws ArithmeticException if the result overflows an int
351         */
352        public Hours plus(int hours) {
353            if (hours == 0) {
354                return this;
355            }
356            return Hours.hours(FieldUtils.safeAdd(getValue(), hours));
357        }
358    
359        /**
360         * Returns a new instance with the specified number of hours added.
361         * <p>
362         * This instance is immutable and unaffected by this method call.
363         *
364         * @param hours  the amount of hours to add, may be negative, null means zero
365         * @return the new period plus the specified number of hours
366         * @throws ArithmeticException if the result overflows an int
367         */
368        public Hours plus(Hours hours) {
369            if (hours == null) {
370                return this;
371            }
372            return plus(hours.getValue());
373        }
374    
375        //-----------------------------------------------------------------------
376        /**
377         * Returns a new instance with the specified number of hours taken away.
378         * <p>
379         * This instance is immutable and unaffected by this method call.
380         *
381         * @param hours  the amount of hours to take away, may be negative
382         * @return the new period minus the specified number of hours
383         * @throws ArithmeticException if the result overflows an int
384         */
385        public Hours minus(int hours) {
386            return plus(FieldUtils.safeNegate(hours));
387        }
388    
389        /**
390         * Returns a new instance with the specified number of hours taken away.
391         * <p>
392         * This instance is immutable and unaffected by this method call.
393         *
394         * @param hours  the amount of hours to take away, may be negative, null means zero
395         * @return the new period minus the specified number of hours
396         * @throws ArithmeticException if the result overflows an int
397         */
398        public Hours minus(Hours hours) {
399            if (hours == null) {
400                return this;
401            }
402            return minus(hours.getValue());
403        }
404    
405        //-----------------------------------------------------------------------
406        /**
407         * Returns a new instance with the hours multiplied by the specified scalar.
408         * <p>
409         * This instance is immutable and unaffected by this method call.
410         *
411         * @param scalar  the amount to multiply by, may be negative
412         * @return the new period multiplied by the specified scalar
413         * @throws ArithmeticException if the result overflows an int
414         */
415        public Hours multipliedBy(int scalar) {
416            return Hours.hours(FieldUtils.safeMultiply(getValue(), scalar));
417        }
418    
419        /**
420         * Returns a new instance with the hours divided by the specified divisor.
421         * The calculation uses integer division, thus 3 divided by 2 is 1.
422         * <p>
423         * This instance is immutable and unaffected by this method call.
424         *
425         * @param divisor  the amount to divide by, may be negative
426         * @return the new period divided by the specified divisor
427         * @throws ArithmeticException if the divisor is zero
428         */
429        public Hours dividedBy(int divisor) {
430            if (divisor == 1) {
431                return this;
432            }
433            return Hours.hours(getValue() / divisor);
434        }
435    
436        //-----------------------------------------------------------------------
437        /**
438         * Returns a new instance with the hours value negated.
439         *
440         * @return the new period with a negated value
441         * @throws ArithmeticException if the result overflows an int
442         */
443        public Hours negated() {
444            return Hours.hours(FieldUtils.safeNegate(getValue()));
445        }
446    
447        //-----------------------------------------------------------------------
448        /**
449         * Is this hours instance greater than the specified number of hours.
450         *
451         * @param other  the other period, null means zero
452         * @return true if this hours instance is greater than the specified one
453         */
454        public boolean isGreaterThan(Hours other) {
455            if (other == null) {
456                return getValue() > 0;
457            }
458            return getValue() > other.getValue();
459        }
460    
461        /**
462         * Is this hours instance less than the specified number of hours.
463         *
464         * @param other  the other period, null means zero
465         * @return true if this hours instance is less than the specified one
466         */
467        public boolean isLessThan(Hours other) {
468            if (other == null) {
469                return getValue() < 0;
470            }
471            return getValue() < other.getValue();
472        }
473    
474        //-----------------------------------------------------------------------
475        /**
476         * Gets this instance as a String in the ISO8601 duration format.
477         * <p>
478         * For example, "PT4H" represents 4 hours.
479         *
480         * @return the value as an ISO8601 string
481         */
482        public String toString() {
483            return "PT" + String.valueOf(getValue()) + "H";
484        }
485    
486    }