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 */
016package org.joda.time;
017
018import org.joda.time.base.BaseSingleFieldPeriod;
019import org.joda.time.field.FieldUtils;
020import org.joda.time.format.ISOPeriodFormat;
021import 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 */
040public 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}