1 /* |
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2 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 /* |
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27 * This file is available under and governed by the GNU General Public |
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28 * License version 2 only, as published by the Free Software Foundation. |
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29 * However, the following notice accompanied the original version of this |
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30 * file: |
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31 * |
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32 * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos |
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33 * |
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34 * All rights reserved. |
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35 * |
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36 * Redistribution and use in source and binary forms, with or without |
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37 * modification, are permitted provided that the following conditions are met: |
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38 * |
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39 * * Redistributions of source code must retain the above copyright notice, |
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40 * this list of conditions and the following disclaimer. |
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41 * |
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42 * * Redistributions in binary form must reproduce the above copyright notice, |
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43 * this list of conditions and the following disclaimer in the documentation |
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44 * and/or other materials provided with the distribution. |
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45 * |
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46 * * Neither the name of JSR-310 nor the names of its contributors |
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47 * may be used to endorse or promote products derived from this software |
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48 * without specific prior written permission. |
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49 * |
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50 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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51 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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52 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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53 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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54 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
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55 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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56 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
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57 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
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58 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
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59 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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60 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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61 */ |
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62 package java.time.temporal; |
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63 |
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64 import static java.time.temporal.ChronoField.ERA; |
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65 import static java.time.temporal.ChronoUnit.ERAS; |
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66 |
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67 import java.time.DateTimeException; |
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68 import java.time.format.DateTimeFormatterBuilder; |
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69 import java.time.format.TextStyle; |
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70 import java.util.Locale; |
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71 |
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72 /** |
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73 * An era of the time-line. |
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74 * <p> |
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75 * Most calendar systems have a single epoch dividing the time-line into two eras. |
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76 * However, some calendar systems, have multiple eras, such as one for the reign |
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77 * of each leader. |
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78 * In all cases, the era is conceptually the largest division of the time-line. |
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79 * Each chronology defines the Era's that are known Eras and a |
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80 * {@link Chrono#eras Chrono.eras} to get the valid eras. |
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81 * <p> |
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82 * For example, the Thai Buddhist calendar system divides time into two eras, |
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83 * before and after a single date. By contrast, the Japanese calendar system |
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84 * has one era for the reign of each Emperor. |
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85 * <p> |
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86 * Instances of {@code Era} may be compared using the {@code ==} operator. |
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87 * |
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88 * <h3>Specification for implementors</h3> |
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89 * This interface must be implemented with care to ensure other classes operate correctly. |
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90 * All implementations must be singletons - final, immutable and thread-safe. |
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91 * It is recommended to use an enum whenever possible. |
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92 * |
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93 * @param <C> the chronology of the era |
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94 * @since 1.8 |
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95 */ |
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96 public interface Era<C extends Chrono<C>> extends TemporalAccessor, TemporalAdjuster { |
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97 |
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98 /** |
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99 * Gets the numeric value associated with the era as defined by the chronology. |
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100 * Each chronology defines the predefined Eras and methods to list the Eras |
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101 * of the chronology. |
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102 * <p> |
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103 * All fields, including eras, have an associated numeric value. |
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104 * The meaning of the numeric value for era is determined by the chronology |
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105 * according to these principles: |
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106 * <p><ul> |
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107 * <li>The era in use at the epoch 1970-01-01 (ISO) has the value 1. |
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108 * <li>Later eras have sequentially higher values. |
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109 * <li>Earlier eras have sequentially lower values, which may be negative. |
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110 * </ul><p> |
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111 * |
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112 * @return the numeric era value |
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113 */ |
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114 int getValue(); |
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115 |
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116 /** |
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117 * Gets the chronology of this era. |
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118 * <p> |
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119 * The {@code Chrono} represents the calendar system in use. |
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120 * This always returns the standard form of the chronology. |
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121 * |
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122 * @return the chronology, not null |
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123 */ |
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124 C getChrono(); |
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125 |
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126 //----------------------------------------------------------------------- |
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127 /** |
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128 * Obtains a date in this era given the year-of-era, month, and day. |
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129 * <p> |
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130 * This era is combined with the given date fields to form a date. |
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131 * The year specified must be the year-of-era. |
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132 * Methods to create a date from the proleptic-year are on {@code Chrono}. |
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133 * This always uses the standard form of the chronology. |
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134 * <p> |
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135 * This default implementation invokes the factory method on {@link Chrono}. |
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136 * |
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137 * @param yearOfEra the calendar system year-of-era |
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138 * @param month the calendar system month-of-year |
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139 * @param day the calendar system day-of-month |
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140 * @return a local date based on this era and the specified year-of-era, month and day |
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141 */ |
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142 public default ChronoLocalDate<C> date(int yearOfEra, int month, int day) { |
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143 return getChrono().date(this, yearOfEra, month, day); |
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144 } |
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145 |
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146 |
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147 /** |
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148 * Obtains a date in this era given year-of-era and day-of-year fields. |
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149 * <p> |
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150 * This era is combined with the given date fields to form a date. |
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151 * The year specified must be the year-of-era. |
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152 * Methods to create a date from the proleptic-year are on {@code Chrono}. |
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153 * This always uses the standard form of the chronology. |
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154 * <p> |
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155 * This default implementation invokes the factory method on {@link Chrono}. |
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156 * |
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157 * @param yearOfEra the calendar system year-of-era |
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158 * @param dayOfYear the calendar system day-of-year |
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159 * @return a local date based on this era and the specified year-of-era and day-of-year |
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160 */ |
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161 public default ChronoLocalDate<C> dateYearDay(int yearOfEra, int dayOfYear) { |
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162 return getChrono().dateYearDay(this, yearOfEra, dayOfYear); |
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163 } |
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164 |
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165 //----------------------------------------------------------------------- |
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166 /** |
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167 * Checks if the specified field is supported. |
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168 * <p> |
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169 * This checks if this era can be queried for the specified field. |
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170 * If false, then calling the {@link #range(TemporalField) range} and |
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171 * {@link #get(TemporalField) get} methods will throw an exception. |
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172 * <p> |
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173 * If the field is a {@link ChronoField} then the query is implemented here. |
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174 * The {@code ERA} field returns true. |
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175 * All other {@code ChronoField} instances will return false. |
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176 * <p> |
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177 * If the field is not a {@code ChronoField}, then the result of this method |
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178 * is obtained by invoking {@code TemporalField.doIsSupported(TemporalAccessor)} |
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179 * passing {@code this} as the argument. |
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180 * Whether the field is supported is determined by the field. |
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181 * |
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182 * @param field the field to check, null returns false |
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183 * @return true if the field is supported on this era, false if not |
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184 */ |
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185 @Override |
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186 public default boolean isSupported(TemporalField field) { |
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187 if (field instanceof ChronoField) { |
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188 return field == ERA; |
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189 } |
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190 return field != null && field.doIsSupported(this); |
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191 } |
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192 |
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193 /** |
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194 * Gets the range of valid values for the specified field. |
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195 * <p> |
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196 * The range object expresses the minimum and maximum valid values for a field. |
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197 * This era is used to enhance the accuracy of the returned range. |
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198 * If it is not possible to return the range, because the field is not supported |
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199 * or for some other reason, an exception is thrown. |
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200 * <p> |
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201 * If the field is a {@link ChronoField} then the query is implemented here. |
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202 * The {@code ERA} field returns the range. |
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203 * All other {@code ChronoField} instances will throw a {@code DateTimeException}. |
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204 * <p> |
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205 * If the field is not a {@code ChronoField}, then the result of this method |
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206 * is obtained by invoking {@code TemporalField.doRange(TemporalAccessor)} |
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207 * passing {@code this} as the argument. |
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208 * Whether the range can be obtained is determined by the field. |
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209 * |
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210 * @param field the field to query the range for, not null |
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211 * @return the range of valid values for the field, not null |
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212 * @throws DateTimeException if the range for the field cannot be obtained |
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213 */ |
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214 @Override // override for Javadoc |
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215 public default ValueRange range(TemporalField field) { |
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216 return TemporalAccessor.super.range(field); |
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217 } |
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218 |
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219 /** |
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220 * Gets the value of the specified field from this era as an {@code int}. |
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221 * <p> |
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222 * This queries this era for the value for the specified field. |
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223 * The returned value will always be within the valid range of values for the field. |
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224 * If it is not possible to return the value, because the field is not supported |
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225 * or for some other reason, an exception is thrown. |
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226 * <p> |
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227 * If the field is a {@link ChronoField} then the query is implemented here. |
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228 * The {@code ERA} field returns the value of the era. |
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229 * All other {@code ChronoField} instances will throw a {@code DateTimeException}. |
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230 * <p> |
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231 * If the field is not a {@code ChronoField}, then the result of this method |
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232 * is obtained by invoking {@code TemporalField.doGet(TemporalAccessor)} |
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233 * passing {@code this} as the argument. Whether the value can be obtained, |
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234 * and what the value represents, is determined by the field. |
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235 * |
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236 * @param field the field to get, not null |
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237 * @return the value for the field |
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238 * @throws DateTimeException if a value for the field cannot be obtained |
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239 * @throws ArithmeticException if numeric overflow occurs |
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240 */ |
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241 @Override // override for Javadoc and performance |
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242 public default int get(TemporalField field) { |
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243 if (field == ERA) { |
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244 return getValue(); |
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245 } |
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246 return range(field).checkValidIntValue(getLong(field), field); |
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247 } |
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248 |
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249 /** |
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250 * Gets the value of the specified field from this era as a {@code long}. |
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251 * <p> |
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252 * This queries this era for the value for the specified field. |
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253 * If it is not possible to return the value, because the field is not supported |
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254 * or for some other reason, an exception is thrown. |
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255 * <p> |
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256 * If the field is a {@link ChronoField} then the query is implemented here. |
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257 * The {@code ERA} field returns the value of the era. |
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258 * All other {@code ChronoField} instances will throw a {@code DateTimeException}. |
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259 * <p> |
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260 * If the field is not a {@code ChronoField}, then the result of this method |
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261 * is obtained by invoking {@code TemporalField.doGet(TemporalAccessor)} |
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262 * passing {@code this} as the argument. Whether the value can be obtained, |
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263 * and what the value represents, is determined by the field. |
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264 * |
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265 * @param field the field to get, not null |
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266 * @return the value for the field |
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267 * @throws DateTimeException if a value for the field cannot be obtained |
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268 * @throws ArithmeticException if numeric overflow occurs |
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269 */ |
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270 @Override |
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271 public default long getLong(TemporalField field) { |
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272 if (field == ERA) { |
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273 return getValue(); |
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274 } else if (field instanceof ChronoField) { |
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275 throw new DateTimeException("Unsupported field: " + field.getName()); |
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276 } |
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277 return field.doGet(this); |
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278 } |
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279 |
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280 //----------------------------------------------------------------------- |
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281 /** |
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282 * Queries this era using the specified query. |
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283 * <p> |
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284 * This queries this era using the specified query strategy object. |
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285 * The {@code TemporalQuery} object defines the logic to be used to |
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286 * obtain the result. Read the documentation of the query to understand |
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287 * what the result of this method will be. |
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288 * <p> |
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289 * The result of this method is obtained by invoking the |
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290 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the |
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291 * specified query passing {@code this} as the argument. |
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292 * |
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293 * @param <R> the type of the result |
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294 * @param query the query to invoke, not null |
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295 * @return the query result, null may be returned (defined by the query) |
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296 * @throws DateTimeException if unable to query (defined by the query) |
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297 * @throws ArithmeticException if numeric overflow occurs (defined by the query) |
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298 */ |
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299 @SuppressWarnings("unchecked") |
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300 @Override |
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301 public default <R> R query(TemporalQuery<R> query) { |
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302 if (query == Queries.chrono()) { |
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303 return (R) getChrono(); |
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304 } else if (query == Queries.precision()) { |
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305 return (R) ERAS; |
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306 } |
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307 return TemporalAccessor.super.query(query); |
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308 } |
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309 |
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310 /** |
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311 * Adjusts the specified temporal object to have the same era as this object. |
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312 * <p> |
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313 * This returns a temporal object of the same observable type as the input |
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314 * with the era changed to be the same as this. |
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315 * <p> |
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316 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)} |
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317 * passing {@link ChronoField#ERA} as the field. |
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318 * <p> |
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319 * In most cases, it is clearer to reverse the calling pattern by using |
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320 * {@link Temporal#with(TemporalAdjuster)}: |
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321 * <pre> |
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322 * // these two lines are equivalent, but the second approach is recommended |
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323 * temporal = thisEra.adjustInto(temporal); |
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324 * temporal = temporal.with(thisEra); |
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325 * </pre> |
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326 * <p> |
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327 * This instance is immutable and unaffected by this method call. |
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328 * |
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329 * @param temporal the target object to be adjusted, not null |
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330 * @return the adjusted object, not null |
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331 * @throws DateTimeException if unable to make the adjustment |
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332 * @throws ArithmeticException if numeric overflow occurs |
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333 */ |
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334 @Override |
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335 public default Temporal adjustInto(Temporal temporal) { |
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336 return temporal.with(ERA, getValue()); |
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337 } |
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338 |
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339 //----------------------------------------------------------------------- |
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340 /** |
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341 * Gets the textual representation of this era. |
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342 * <p> |
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343 * This returns the textual name used to identify the era. |
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344 * The parameters control the style of the returned text and the locale. |
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345 * <p> |
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346 * If no textual mapping is found then the {@link #getValue() numeric value} is returned. |
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347 * <p> |
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348 * This default implementation is suitable for all implementations. |
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349 * |
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350 * @param style the style of the text required, not null |
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351 * @param locale the locale to use, not null |
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352 * @return the text value of the era, not null |
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353 */ |
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354 public default String getText(TextStyle style, Locale locale) { |
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355 return new DateTimeFormatterBuilder().appendText(ERA, style).toFormatter(locale).print(this); |
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356 } |
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357 |
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358 // NOTE: methods to convert year-of-era/proleptic-year cannot be here as they may depend on month/day (Japanese) |
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359 } |
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