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Java example source code file (Days.java)

This example Java source code file (Days.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

days, duration, five, four, localdate, max_value, min_value, one, seven, six, three, two, zero

The Days.java Java example source code

/*
 *  Copyright 2001-2010 Stephen Colebourne
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.joda.time;

import org.joda.convert.FromString;
import org.joda.convert.ToString;
import org.joda.time.base.BaseSingleFieldPeriod;
import org.joda.time.field.FieldUtils;
import org.joda.time.format.ISOPeriodFormat;
import org.joda.time.format.PeriodFormatter;

/**
 * An immutable time period representing a number of days.
 * <p>
 * <code>Days is an immutable period that can only store days.
 * It does not store years, months or hours for example. As such it is a
 * type-safe way of representing a number of days in an application.
 * <p>
 * The number of days is set in the constructor, and may be queried using
 * <code>getDays(). Basic mathematical operations are provided -
 * <code>plus(), minus(), multipliedBy() and
 * <code>dividedBy().
 * <p>
 * <code>Days is thread-safe and immutable.
 *
 * @author Stephen Colebourne
 * @since 1.4
 */
public final class Days extends BaseSingleFieldPeriod {

    /** Constant representing zero days. */
    public static final Days ZERO = new Days(0);
    /** Constant representing one day. */
    public static final Days ONE = new Days(1);
    /** Constant representing two days. */
    public static final Days TWO = new Days(2);
    /** Constant representing three days. */
    public static final Days THREE = new Days(3);
    /** Constant representing four days. */
    public static final Days FOUR = new Days(4);
    /** Constant representing five days. */
    public static final Days FIVE = new Days(5);
    /** Constant representing six days. */
    public static final Days SIX = new Days(6);
    /** Constant representing seven days. */
    public static final Days SEVEN = new Days(7);
    /** Constant representing the maximum number of days that can be stored in this object. */
    public static final Days MAX_VALUE = new Days(Integer.MAX_VALUE);
    /** Constant representing the minimum number of days that can be stored in this object. */
    public static final Days MIN_VALUE = new Days(Integer.MIN_VALUE);

    /** The paser to use for this class. */
    private static final PeriodFormatter PARSER = ISOPeriodFormat.standard().withParseType(PeriodType.days());
    /** Serialization version. */
    private static final long serialVersionUID = 87525275727380865L;

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of <code>Days that may be cached.
     * <code>Days is immutable, so instances can be cached and shared.
     * This factory method provides access to shared instances.
     *
     * @param days  the number of days to obtain an instance for
     * @return the instance of Days
     */
    public static Days days(int days) {
        switch (days) {
            case 0:
                return ZERO;
            case 1:
                return ONE;
            case 2:
                return TWO;
            case 3:
                return THREE;
            case 4:
                return FOUR;
            case 5:
                return FIVE;
            case 6:
                return SIX;
            case 7:
                return SEVEN;
            case Integer.MAX_VALUE:
                return MAX_VALUE;
            case Integer.MIN_VALUE:
                return MIN_VALUE;
            default:
                return new Days(days);
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Creates a <code>Days representing the number of whole days
     * between the two specified datetimes. This method corectly handles
     * any daylight savings time changes that may occur during the interval.
     *
     * @param start  the start instant, must not be null
     * @param end  the end instant, must not be null
     * @return the period in days
     * @throws IllegalArgumentException if the instants are null or invalid
     */
    public static Days daysBetween(ReadableInstant start, ReadableInstant end) {
        int amount = BaseSingleFieldPeriod.between(start, end, DurationFieldType.days());
        return Days.days(amount);
    }

    /**
     * Creates a <code>Days representing the number of whole days
     * between the two specified partial datetimes.
     * <p>
     * The two partials must contain the same fields, for example you can specify
     * two <code>LocalDate objects.
     *
     * @param start  the start partial date, must not be null
     * @param end  the end partial date, must not be null
     * @return the period in days
     * @throws IllegalArgumentException if the partials are null or invalid
     */
    public static Days daysBetween(ReadablePartial start, ReadablePartial end) {
        if (start instanceof LocalDate && end instanceof LocalDate)   {
            Chronology chrono = DateTimeUtils.getChronology(start.getChronology());
            int days = chrono.days().getDifference(
                    ((LocalDate) end).getLocalMillis(), ((LocalDate) start).getLocalMillis());
            return Days.days(days);
        }
        int amount = BaseSingleFieldPeriod.between(start, end, ZERO);
        return Days.days(amount);
    }

    /**
     * Creates a <code>Days representing the number of whole days
     * in the specified interval. This method corectly handles any daylight
     * savings time changes that may occur during the interval.
     *
     * @param interval  the interval to extract days from, null returns zero
     * @return the period in days
     * @throws IllegalArgumentException if the partials are null or invalid
     */
    public static Days daysIn(ReadableInterval interval) {
        if (interval == null)   {
            return Days.ZERO;
        }
        int amount = BaseSingleFieldPeriod.between(interval.getStart(), interval.getEnd(), DurationFieldType.days());
        return Days.days(amount);
    }

    /**
     * Creates a new <code>Days representing the number of complete
     * standard length days in the specified period.
     * <p>
     * This factory method converts all fields from the period to hours using standardised
     * durations for each field. Only those fields which have a precise duration in
     * the ISO UTC chronology can be converted.
     * <ul>
     * <li>One week consists of 7 days.
     * <li>One day consists of 24 hours.
     * <li>One hour consists of 60 minutes.
     * <li>One minute consists of 60 seconds.
     * <li>One second consists of 1000 milliseconds.
     * </ul>
     * Months and Years are imprecise and periods containing these values cannot be converted.
     *
     * @param period  the period to get the number of hours from, null returns zero
     * @return the period in days
     * @throws IllegalArgumentException if the period contains imprecise duration values
     */
    public static Days standardDaysIn(ReadablePeriod period) {
        int amount = BaseSingleFieldPeriod.standardPeriodIn(period, DateTimeConstants.MILLIS_PER_DAY);
        return Days.days(amount);
    }

    /**
     * Creates a new <code>Days by parsing a string in the ISO8601 format 'PnD'.
     * <p>
     * The parse will accept the full ISO syntax of PnYnMnWnDTnHnMnS however only the
     * days component may be non-zero. If any other component is non-zero, an exception
     * will be thrown.
     *
     * @param periodStr  the period string, null returns zero
     * @return the period in days
     * @throws IllegalArgumentException if the string format is invalid
     */
    @FromString
    public static Days parseDays(String periodStr) {
        if (periodStr == null) {
            return Days.ZERO;
        }
        Period p = PARSER.parsePeriod(periodStr);
        return Days.days(p.getDays());
    }

    //-----------------------------------------------------------------------
    /**
     * Creates a new instance representing a number of days.
     * You should consider using the factory method {@link #days(int)}
     * instead of the constructor.
     *
     * @param days  the number of days to represent
     */
    private Days(int days) {
        super(days);
    }

    /**
     * Resolves singletons.
     * 
     * @return the singleton instance
     */
    private Object readResolve() {
        return Days.days(getValue());
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the duration field type, which is <code>days.
     *
     * @return the period type
     */
    public DurationFieldType getFieldType() {
        return DurationFieldType.days();
    }

    /**
     * Gets the period type, which is <code>days.
     *
     * @return the period type
     */
    public PeriodType getPeriodType() {
        return PeriodType.days();
    }

    //-----------------------------------------------------------------------
    /**
     * Converts this period in days to a period in weeks assuming a
     * 7 day week.
     * <p>
     * This method allows you to convert between different types of period.
     * However to achieve this it makes the assumption that all weeks are
     * 7 days long.
     * This may not be true for some unusual chronologies. However, it is included
     * as it is a useful operation for many applications and business rules.
     * 
     * @return a period representing the number of weeks for this number of days
     */
    public Weeks toStandardWeeks() {
        return Weeks.weeks(getValue() / DateTimeConstants.DAYS_PER_WEEK);
    }

    /**
     * Converts this period in days to a period in hours assuming a
     * 24 hour day.
     * <p>
     * This method allows you to convert between different types of period.
     * However to achieve this it makes the assumption that all days are 24 hours long.
     * This is not true when daylight savings is considered and may also not
     * be true for some unusual chronologies. However, it is included
     * as it is a useful operation for many applications and business rules.
     * 
     * @return a period representing the number of hours for this number of days
     * @throws ArithmeticException if the number of hours is too large to be represented
     */
    public Hours toStandardHours() {
        return Hours.hours(FieldUtils.safeMultiply(getValue(), DateTimeConstants.HOURS_PER_DAY));
    }

    /**
     * Converts this period in days to a period in minutes assuming a
     * 24 hour day and 60 minute hour.
     * <p>
     * This method allows you to convert between different types of period.
     * However to achieve this it makes the assumption that all days are 24 hours
     * long and all hours are 60 minutes long.
     * This is not true when daylight savings is considered and may also not
     * be true for some unusual chronologies. However, it is included
     * as it is a useful operation for many applications and business rules.
     * 
     * @return a period representing the number of minutes for this number of days
     * @throws ArithmeticException if the number of minutes is too large to be represented
     */
    public Minutes toStandardMinutes() {
        return Minutes.minutes(FieldUtils.safeMultiply(getValue(), DateTimeConstants.MINUTES_PER_DAY));
    }

    /**
     * Converts this period in days to a period in seconds assuming a
     * 24 hour day, 60 minute hour and 60 second minute.
     * <p>
     * This method allows you to convert between different types of period.
     * However to achieve this it makes the assumption that all days are 24 hours
     * long, all hours are 60 minutes long and all minutes are 60 seconds long.
     * This is not true when daylight savings is considered and may also not
     * be true for some unusual chronologies. However, it is included
     * as it is a useful operation for many applications and business rules.
     * 
     * @return a period representing the number of seconds for this number of days
     * @throws ArithmeticException if the number of seconds is too large to be represented
     */
    public Seconds toStandardSeconds() {
        return Seconds.seconds(FieldUtils.safeMultiply(getValue(), DateTimeConstants.SECONDS_PER_DAY));
    }

    //-----------------------------------------------------------------------
    /**
     * Converts this period in days to a duration in milliseconds assuming a
     * 24 hour day, 60 minute hour and 60 second minute.
     * <p>
     * This method allows you to convert from a period to a duration.
     * However to achieve this it makes the assumption that all days are 24 hours
     * long, all hours are 60 minutes and all minutes are 60 seconds.
     * This is not true when daylight savings time is considered, and may also
     * not be true for some unusual chronologies. However, it is included as it
     * is a useful operation for many applications and business rules.
     * 
     * @return a duration equivalent to this number of days
     */
    public Duration toStandardDuration() {
        long days = getValue();  // assign to a long
        return new Duration(days * DateTimeConstants.MILLIS_PER_DAY);
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the number of days that this period represents.
     *
     * @return the number of days in the period
     */
    public int getDays() {
        return getValue();
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a new instance with the specified number of days added.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param days  the amount of days to add, may be negative
     * @return the new period plus the specified number of days
     * @throws ArithmeticException if the result overflows an int
     */
    public Days plus(int days) {
        if (days == 0) {
            return this;
        }
        return Days.days(FieldUtils.safeAdd(getValue(), days));
    }

    /**
     * Returns a new instance with the specified number of days added.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param days  the amount of days to add, may be negative, null means zero
     * @return the new period plus the specified number of days
     * @throws ArithmeticException if the result overflows an int
     */
    public Days plus(Days days) {
        if (days == null) {
            return this;
        }
        return plus(days.getValue());
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a new instance with the specified number of days taken away.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param days  the amount of days to take away, may be negative
     * @return the new period minus the specified number of days
     * @throws ArithmeticException if the result overflows an int
     */
    public Days minus(int days) {
        return plus(FieldUtils.safeNegate(days));
    }

    /**
     * Returns a new instance with the specified number of days taken away.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param days  the amount of days to take away, may be negative, null means zero
     * @return the new period minus the specified number of days
     * @throws ArithmeticException if the result overflows an int
     */
    public Days minus(Days days) {
        if (days == null) {
            return this;
        }
        return minus(days.getValue());
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a new instance with the days multiplied by the specified scalar.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param scalar  the amount to multiply by, may be negative
     * @return the new period multiplied by the specified scalar
     * @throws ArithmeticException if the result overflows an int
     */
    public Days multipliedBy(int scalar) {
        return Days.days(FieldUtils.safeMultiply(getValue(), scalar));
    }

    /**
     * Returns a new instance with the days divided by the specified divisor.
     * The calculation uses integer division, thus 3 divided by 2 is 1.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param divisor  the amount to divide by, may be negative
     * @return the new period divided by the specified divisor
     * @throws ArithmeticException if the divisor is zero
     */
    public Days dividedBy(int divisor) {
        if (divisor == 1) {
            return this;
        }
        return Days.days(getValue() / divisor);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a new instance with the days value negated.
     *
     * @return the new period with a negated value
     * @throws ArithmeticException if the result overflows an int
     */
    public Days negated() {
        return Days.days(FieldUtils.safeNegate(getValue()));
    }

    //-----------------------------------------------------------------------
    /**
     * Is this days instance greater than the specified number of days.
     *
     * @param other  the other period, null means zero
     * @return true if this days instance is greater than the specified one
     */
    public boolean isGreaterThan(Days other) {
        if (other == null) {
            return getValue() > 0;
        }
        return getValue() > other.getValue();
    }

    /**
     * Is this days instance less than the specified number of days.
     *
     * @param other  the other period, null means zero
     * @return true if this days instance is less than the specified one
     */
    public boolean isLessThan(Days other) {
        if (other == null) {
            return getValue() < 0;
        }
        return getValue() < other.getValue();
    }

    //-----------------------------------------------------------------------
    /**
     * Gets this instance as a String in the ISO8601 duration format.
     * <p>
     * For example, "P4D" represents 4 days.
     *
     * @return the value as an ISO8601 string
     */
    @ToString
    public String toString() {
        return "P" + String.valueOf(getValue()) + "D";
    }

}

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