commit f17ff818ef6094d70eca51705195bb7cc0f9e7e8
author yumaoka <y.umaoka@gmail.com> Wed Apr 10 20:42:23 2019 -0400
committer Yoshito Umaoka <yumaoka@users.noreply.github.com> Thu Apr 11 00:08:04 2019 -0400
tree eaffb4c97d6bcc3b2d5cda43b38c84ab0035098f
parent 5b3f1c01ed31f50a24c5e57b4b9cd558982e088e

ICU-20550 jaEra: use all valid eras for calendar calculations (Java port)

icu4j/main/classes/core/src/com/ibm/icu/util/JapaneseCalendar.java

diff --git a/icu4j/main/classes/core/src/com/ibm/icu/util/JapaneseCalendar.java b/icu4j/main/classes/core/src/com/ibm/icu/util/JapaneseCalendar.java
index 11a4a86..4939188 100644
--- a/icu4j/main/classes/core/src/com/ibm/icu/util/JapaneseCalendar.java
+++ b/icu4j/main/classes/core/src/com/ibm/icu/util/JapaneseCalendar.java
@@ -419,7 +419,7 @@
             if (limitType == MINIMUM || limitType == GREATEST_MINIMUM) {
                 return 0;
             }
-            return CURRENT_ERA;
+            return ERA_RULES.getNumberOfEras() - 1; // max known era, not always CURRENT_ERA
         case YEAR:
         {
             switch (limitType) {
@@ -466,7 +466,7 @@
     public int getActualMaximum(int field) {
         if (field == YEAR) {
             int era = get(Calendar.ERA);
-            if (era == CURRENT_ERA) {
+            if (era == ERA_RULES.getNumberOfEras() - 1) {
                 // TODO: Investigate what value should be used here - revisit after 4.0.
                 return handleGetLimit(YEAR, MAXIMUM);
             } else {

icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/JapaneseTest.java

diff --git a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/JapaneseTest.java b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/JapaneseTest.java
index 0313299..26d204d 100644
--- a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/JapaneseTest.java
+++ b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/JapaneseTest.java
@@ -450,5 +450,33 @@
         doLimitsTest(jcal, null, cal.getTime());
         doTheoreticalLimitsTest(jcal, true);
     }
+
+    // The following currently assumes that Reiwa is the last known/valid era.
+    // Filed ICU-20551 to generalize this when we have more time...
+    @Test
+    public void TestJpnCalAddSetNextEra() {
+        final JapaneseCalendar jCal = new JapaneseCalendar();
+        jCal.clear();   // This sets to 1970 in Showa
+
+        final int sEra = jCal.get(Calendar.ERA);  // Don't assume era number for Showa
+        final int[] startYears = { 1926, 1989, 2019, 0 };    // start years for Show, Heisei, Reiwa; 0 marks invalid era beyond
+
+        for (int iEra = 1; iEra < 3; iEra++) {
+            jCal.clear();
+            jCal.set(Calendar.ERA, sEra + iEra);
+            int eYear = jCal.get(Calendar.EXTENDED_YEAR);
+            if (eYear != startYears[iEra]) {
+                errln("ERROR: set " + iEra + ", expected start year " + startYears[iEra] + " but get " + eYear);
+            } else {
+                jCal.add(Calendar.ERA, 1);
+                eYear = jCal.get(Calendar.EXTENDED_YEAR);
+                int nextEraStart = (startYears[iEra + 1] == 0) ? startYears[iEra] : startYears[iEra + 1];
+                if (eYear != nextEraStart) {
+                    errln("ERROR: set " + iEra + " then add ERA 1, expected start year " + nextEraStart
+                            + " but get " + eYear);
+                }
+            }
+        }
+    }
 }