    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.lang3.time;
    019
    020import java.time.LocalDate;
    021import java.time.LocalDateTime;
    022import java.time.OffsetDateTime;
    023import java.time.ZoneId;
    024import java.time.ZonedDateTime;
    025import java.util.Calendar;
    026import java.util.Locale;
    027import java.util.Locale.Category;
    028import java.util.Map;
    029import java.util.Objects;
    030
    031/**
    032 * Helps use {@link Calendar}s.
    033 *
    034 * @since 3.10
    035 */
    036public class CalendarUtils {
    037
    038    /**
    039     * The singleton instance for {@link Calendar#getInstance()}. The instance is created when the class is initialized and is based on the current time in the
    040     * default time zone with the default {@link Category#FORMAT} locale.
    041     *
    042     * @see CalendarUtils#getInstance()
    043     */
    044    public static final CalendarUtils INSTANCE = getInstance();
    045
    046    /**
    047     * Creates a new instance based on the current time in the default time zone with the default {@link Category#FORMAT} locale.
    048     *
    049     * @return a new instance.
    050     * @since 3.14.0
    051     */
    052    public static CalendarUtils getInstance() {
    053        return new CalendarUtils(Calendar.getInstance());
    054    }
    055
    056    /**
    057     * Gets a CalendarUtils using the default time zone and specified locale. The {@code CalendarUtils} returned is based on the current time in the
    058     * default time zone with the given locale.
    059     *
    060     * @param locale the locale for the week data
    061     * @return a Calendar.
    062     */
    063    static CalendarUtils getInstance(final Locale locale) {
    064        return new CalendarUtils(Calendar.getInstance(locale), locale);
    065    }
    066
    067    /**
    068     * Converts a Calendar to a LocalDateTime.
    069     *
    070     * @param calendar the Calendar to convert.
    071     * @return a LocalDateTime.
    072     * @since 3.17.0
    073     */
    074    public static LocalDateTime toLocalDateTime(final Calendar calendar) {
    075        return LocalDateTime.ofInstant(calendar.toInstant(), toZoneId(calendar));
    076    }
    077
    078    /**
    079     * Converts a Calendar to a OffsetDateTime.
    080     *
    081     * @param calendar the Calendar to convert.
    082     * @return a OffsetDateTime.
    083     * @since 3.17.0
    084     */
    085    public static OffsetDateTime toOffsetDateTime(final Calendar calendar) {
    086        return OffsetDateTime.ofInstant(calendar.toInstant(), toZoneId(calendar));
    087    }
    088
    089    /**
    090     * Converts a Calendar to a ZonedDateTime.
    091     *
    092     * @param calendar the Calendar to convert.
    093     * @return a ZonedDateTime.
    094     * @since 3.17.0
    095     */
    096    public static ZonedDateTime toZonedDateTime(final Calendar calendar) {
    097        return ZonedDateTime.ofInstant(calendar.toInstant(), toZoneId(calendar));
    098    }
    099
    100    private static ZoneId toZoneId(final Calendar calendar) {
    101        return calendar.getTimeZone().toZoneId();
    102    }
    103
    104    private final Calendar calendar;
    105
    106    private final Locale locale;
    107
    108    /**
    109     * Creates an instance for the given Calendar.
    110     *
    111     * @param calendar A Calendar.
    112     */
    113    public CalendarUtils(final Calendar calendar) {
    114        this(calendar, Locale.getDefault());
    115    }
    116    /**
    117     * Creates an instance for the given Calendar.
    118     *
    119     * @param calendar A Calendar.
    120     * @param locale A Locale.
    121     */
    122    CalendarUtils(final Calendar calendar, final Locale locale) {
    123        this.calendar = Objects.requireNonNull(calendar, "calendar");
    124        this.locale = Objects.requireNonNull(locale, "locale");
    125    }
    126
    127    /**
    128     * Gets the current day of month.
    129     *
    130     * @return the current day of month.
    131     */
    132    public int getDayOfMonth() {
    133        return calendar.get(Calendar.DAY_OF_MONTH);
    134    }
    135
    136    /**
    137     * Gets the current day of year.
    138     *
    139     * @return the current day of year.
    140     * @since 3.13.0
    141     */
    142    public int getDayOfYear() {
    143        return calendar.get(Calendar.DAY_OF_YEAR);
    144    }
    145
    146    /**
    147     * Gets the current month.
    148     *
    149     * @return the current month.
    150     */
    151    public int getMonth() {
    152        return calendar.get(Calendar.MONTH);
    153    }
    154
    155    /**
    156     * Gets month names in the requested style.
    157     * @param style Must be a valid {@link Calendar#getDisplayNames(int, int, Locale)} month style.
    158     * @return Styled names of months
    159     */
    160    String[] getMonthDisplayNames(final int style) {
    161        // Unfortunately standalone month names are not available in DateFormatSymbols,
    162        // so we have to extract them.
    163        final Map<String, Integer> displayNames = calendar.getDisplayNames(Calendar.MONTH, style, locale);
    164        if (displayNames == null) {
    165            return null;
    166        }
    167        final String[] monthNames = new String[displayNames.size()];
    168        displayNames.forEach((k, v) -> monthNames[v] = k);
    169        return monthNames;
    170    }
    171
    172    /**
    173     * Gets full standalone month names as used in "LLLL" date formatting.
    174     * @return Long names of months
    175     */
    176    String[] getStandaloneLongMonthNames() {
    177        return getMonthDisplayNames(Calendar.LONG_STANDALONE);
    178    }
    179
    180    /**
    181     * Gets short standalone month names as used in "LLLL" date formatting.
    182     * @return Short names of months
    183     */
    184    String[] getStandaloneShortMonthNames() {
    185        return getMonthDisplayNames(Calendar.SHORT_STANDALONE);
    186    }
    187
    188    /**
    189     * Gets the current year.
    190     *
    191     * @return the current year.
    192     */
    193    public int getYear() {
    194        return calendar.get(Calendar.YEAR);
    195    }
    196
    197    /**
    198     * Converts this instance to a {@link LocalDate}.
    199     *
    200     * @return a LocalDate.
    201     * @since 3.18.0
    202     */
    203    public LocalDate toLocalDate() {
    204        return toLocalDateTime().toLocalDate();
    205    }
    206
    207    /**
    208     * Converts this instance to a {@link LocalDateTime}.
    209     *
    210     * @return a LocalDateTime.
    211     * @since 3.17.0
    212     */
    213    public LocalDateTime toLocalDateTime() {
    214        return toLocalDateTime(calendar);
    215    }
    216
    217    /**
    218     * Converts this instance to a {@link OffsetDateTime}.
    219     *
    220     * @return a OffsetDateTime.
    221     * @since 3.17.0
    222     */
    223    public OffsetDateTime toOffsetDateTime() {
    224        return toOffsetDateTime(calendar);
    225    }
    226
    227    /**
    228     * Converts this instance to a {@link ZonedDateTime}.
    229     *
    230     * @return a ZonedDateTime.
    231     * @since 3.17.0
    232     */
    233    public ZonedDateTime toZonedDateTime() {
    234        return toZonedDateTime(calendar);
    235    }
    236
    237}