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/* * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved. * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. * * * * * * * * * * * * * * * * * * * * */ /* * * * * * * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos * * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * * Neither the name of JSR-310 nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package java.time.chrono; import static java.time.temporal.ChronoField.ERA; import static java.time.temporal.ChronoUnit.ERAS; import java.time.DateTimeException; import java.time.temporal.UnsupportedTemporalTypeException; import java.time.format.DateTimeFormatterBuilder; import java.time.format.TextStyle; import java.time.temporal.ChronoField; import java.time.temporal.Temporal; import java.time.temporal.TemporalAccessor; import java.time.temporal.TemporalAdjuster; import java.time.temporal.TemporalField; import java.time.temporal.TemporalQueries; import java.time.temporal.TemporalQuery; import java.time.temporal.ValueRange; import java.util.Locale; /** * An era of the time-line. *

* Most calendar systems have a single epoch dividing the time-line into two eras. * However, some calendar systems, have multiple eras, such as one for the reign * of each leader. * In all cases, the era is conceptually the largest division of the time-line. * Each chronology defines the Era's that are known Eras and a * {@link Chronology#eras Chronology.eras} to get the valid eras. *

* For example, the Thai Buddhist calendar system divides time into two eras, * before and after a single date. By contrast, the Japanese calendar system * has one era for the reign of each Emperor. *

* Instances of {@code Era} may be compared using the {@code ==} operator. * * @implSpec * This interface must be implemented with care to ensure other classes operate correctly. * All implementations must be singletons - final, immutable and thread-safe. * It is recommended to use an enum whenever possible. * * @since 1.8 */ public interface Era extends TemporalAccessor, TemporalAdjuster { /** * Gets the numeric value associated with the era as defined by the chronology. * Each chronology defines the predefined Eras and methods to list the Eras * of the chronology. *

* All fields, including eras, have an associated numeric value. * The meaning of the numeric value for era is determined by the chronology * according to these principles: *

The era in use at the epoch 1970-01-01 (ISO) has the value 1. *
Later eras have sequentially higher values. *
Earlier eras have sequentially lower values, which may be negative. *

* * @return the numeric era value */ int getValue(); //----------------------------------------------------------------------- /** * Checks if the specified field is supported. *

* This checks if this era can be queried for the specified field. * If false, then calling the {@link #range(TemporalField) range} and * {@link #get(TemporalField) get} methods will throw an exception. *

* If the field is a {@link ChronoField} then the query is implemented here. * The {@code ERA} field returns true. * All other {@code ChronoField} instances will return false. *

* If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)} * passing {@code this} as the argument. * Whether the field is supported is determined by the field. * * @param field the field to check, null returns false * @return true if the field is supported on this era, false if not */ @Override default boolean isSupported(TemporalField field) { if (field instanceof ChronoField) { return field == ERA; } return field != null && field.isSupportedBy(this); } /** * Gets the range of valid values for the specified field. *

* The range object expresses the minimum and maximum valid values for a field. * This era is used to enhance the accuracy of the returned range. * If it is not possible to return the range, because the field is not supported * or for some other reason, an exception is thrown. *

* If the field is a {@link ChronoField} then the query is implemented here. * The {@code ERA} field returns the range. * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. *

* If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)} * passing {@code this} as the argument. * Whether the range can be obtained is determined by the field. *

* The default implementation must return a range for {@code ERA} from * zero to one, suitable for two era calendar systems such as ISO. * * @param field the field to query the range for, not null * @return the range of valid values for the field, not null * @throws DateTimeException if the range for the field cannot be obtained * @throws UnsupportedTemporalTypeException if the unit is not supported */ @Override // override for Javadoc default ValueRange range(TemporalField field) { return TemporalAccessor.super.range(field); } /** * Gets the value of the specified field from this era as an {@code int}. *

* This queries this era for the value for the specified field. * The returned value will always be within the valid range of values for the field. * If it is not possible to return the value, because the field is not supported * or for some other reason, an exception is thrown. *

* If the field is a {@link ChronoField} then the query is implemented here. * The {@code ERA} field returns the value of the era. * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. *

* If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} * passing {@code this} as the argument. Whether the value can be obtained, * and what the value represents, is determined by the field. * * @param field the field to get, not null * @return the value for the field * @throws DateTimeException if a value for the field cannot be obtained or * the value is outside the range of valid values for the field * @throws UnsupportedTemporalTypeException if the field is not supported or * the range of values exceeds an {@code int} * @throws ArithmeticException if numeric overflow occurs */ @Override // override for Javadoc and performance default int get(TemporalField field) { if (field == ERA) { return getValue(); } return TemporalAccessor.super.get(field); } /** * Gets the value of the specified field from this era as a {@code long}. *

* This queries this era for the value for the specified field. * If it is not possible to return the value, because the field is not supported * or for some other reason, an exception is thrown. *

* If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} * passing {@code this} as the argument. Whether the value can be obtained, * and what the value represents, is determined by the field. * * @param field the field to get, not null * @return the value for the field * @throws DateTimeException if a value for the field cannot be obtained * @throws UnsupportedTemporalTypeException if the field is not supported * @throws ArithmeticException if numeric overflow occurs */ @Override default long getLong(TemporalField field) { if (field == ERA) { return getValue(); } else if (field instanceof ChronoField) { throw new UnsupportedTemporalTypeException("Unsupported field: " + field); } return field.getFrom(this); } //----------------------------------------------------------------------- /** * Queries this era using the specified query. *

* This queries this era using the specified query strategy object. * The {@code TemporalQuery} object defines the logic to be used to * obtain the result. Read the documentation of the query to understand * what the result of this method will be. *

* The result of this method is obtained by invoking the * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the * specified query passing {@code this} as the argument. * * @param the type of the result * @param query the query to invoke, not null * @return the query result, null may be returned (defined by the query) * @throws DateTimeException if unable to query (defined by the query) * @throws ArithmeticException if numeric overflow occurs (defined by the query) */ @SuppressWarnings("unchecked") @Override default R query(TemporalQuery query) { if (query == TemporalQueries.precision()) { return (R) ERAS; } return TemporalAccessor.super.query(query); } /** * Adjusts the specified temporal object to have the same era as this object. *

* This returns a temporal object of the same observable type as the input * with the era changed to be the same as this. *

* The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)} * passing {@link ChronoField#ERA} as the field. *

* In most cases, it is clearer to reverse the calling pattern by using * {@link Temporal#with(TemporalAdjuster)}: *

     *   // these two lines are equivalent, but the second approach is recommended
     *   temporal = thisEra.adjustInto(temporal);
     *   temporal = temporal.with(thisEra);
     *

* This instance is immutable and unaffected by this method call. * * @param temporal the target object to be adjusted, not null * @return the adjusted object, not null * @throws DateTimeException if unable to make the adjustment * @throws ArithmeticException if numeric overflow occurs */ @Override default Temporal adjustInto(Temporal temporal) { return temporal.with(ERA, getValue()); } //----------------------------------------------------------------------- /** * Gets the textual representation of this era. *

* This returns the textual name used to identify the era, * suitable for presentation to the user. * The parameters control the style of the returned text and the locale. *

* If no textual mapping is found then the {@link #getValue() numeric value} is returned. *

* This default implementation is suitable for all implementations. * * @param style the style of the text required, not null * @param locale the locale to use, not null * @return the text value of the era, not null */ default String getDisplayName(TextStyle style, Locale locale) { return new DateTimeFormatterBuilder().appendText(ERA, style).toFormatter(locale).format(this); } // NOTE: methods to convert year-of-era/proleptic-year cannot be here as they may depend on month/day (Japanese) }

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