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 */
016package org.joda.time;
017
018import org.joda.convert.FromString;
019import org.joda.convert.ToString;
020import org.joda.time.base.BaseSingleFieldPeriod;
021import org.joda.time.field.FieldUtils;
022import org.joda.time.format.ISOPeriodFormat;
023import 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 */
042public 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}