* July 30, 1912 (Taisho), December 25, 1926 (Showa), and January 7, 1989 (Heisei). Constants
* for these eras, suitable for use in the <code>UCAL_ERA</code> field, are provided
* in this class. Note that the <em>number</em> used for each era is more or
- * less arbitrary. Currently, the era starting in 1053 AD is era #0; however this
- * may change in the future as we add more historical data. Use the predefined
- * constants rather than using actual, absolute numbers.
+ * less arbitrary. Currently, the era starting in 645 AD is era #0; however this
+ * may change in the future. Use the predefined constants rather than using actual,
+ * absolute numbers.
* <p>
+ * Since ICU4C 63, start date of each era is imported from CLDR. CLDR era data
+ * may contain tentative era in near future with placeholder names. By default,
+ * such era data is not enabled. ICU4C users who want to test the behavior of
+ * the future era can enable this one of following settings (in the priority
+ * order):
+ * <ol>
+ * <li>Environment variable <code>ICU_ENABLE_TENTATIVE_ERA=true</code>.</li>
+ * </nl>
* @internal
*/
class JapaneseCalendar : public GregorianCalendar {
public:
/**
- * Useful constants for JapaneseCalendar.
+ * Check environment variable.
+ * @internal
+ */
+ U_I18N_API static UBool U_EXPORT2 enableTentativeEra(void);
+
+ /**
+ * Useful constants for JapaneseCalendar.
+ * Exported for use by test code.
* @internal
*/
U_I18N_API static uint32_t U_EXPORT2 getCurrentEra(void); // the current era