ICU-20536 Japanese era Reiwa support in ICU4C 53
diff --git a/icu4c/source/data/locales/ar.txt b/icu4c/source/data/locales/ar.txt
index 347910a..fbb3ec6 100644
--- a/icu4c/source/data/locales/ar.txt
+++ b/icu4c/source/data/locales/ar.txt
@@ -1290,6 +1290,7 @@
                     "تيشو",
                     "شووا",
                     "هيسي",
+                    "ريوا",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/bs_Cyrl.txt b/icu4c/source/data/locales/bs_Cyrl.txt
index 4bd8985..785e19d 100755
--- a/icu4c/source/data/locales/bs_Cyrl.txt
+++ b/icu4c/source/data/locales/bs_Cyrl.txt
@@ -1023,6 +1023,7 @@
                     "Таишо",
                     "Шова",
                     "Хаисеи",
+                    "Реива",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/en_HK.txt b/icu4c/source/data/locales/en_HK.txt
index 36d5c50..18982f9 100644
--- a/icu4c/source/data/locales/en_HK.txt
+++ b/icu4c/source/data/locales/en_HK.txt
@@ -366,6 +366,7 @@
                     "Taishō",
                     "Shōwa",
                     "Heisei",
+                    "Reiwa",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/he.txt b/icu4c/source/data/locales/he.txt
index be55e56..762e703 100644
--- a/icu4c/source/data/locales/he.txt
+++ b/icu4c/source/data/locales/he.txt
@@ -1207,6 +1207,7 @@
                     "Taishō",
                     "Shōwa",
                     "Heisei",
+                    "Reiwa",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/hi.txt b/icu4c/source/data/locales/hi.txt
index 886014b..0f6c0ce 100644
--- a/icu4c/source/data/locales/hi.txt
+++ b/icu4c/source/data/locales/hi.txt
@@ -1068,6 +1068,7 @@
                     "ताईशो",
                     "शोवा",
                     "हेईसेई",
+                    "रेइवा",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/id.txt b/icu4c/source/data/locales/id.txt
index 798bc3f..7bd8756 100644
--- a/icu4c/source/data/locales/id.txt
+++ b/icu4c/source/data/locales/id.txt
@@ -1669,6 +1669,7 @@
                     "Taishō",
                     "Shōwa",
                     "Heisei",
+                    "Reiwa",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/ja.txt b/icu4c/source/data/locales/ja.txt
index e2dfa47..1bd3bc8 100644
--- a/icu4c/source/data/locales/ja.txt
+++ b/icu4c/source/data/locales/ja.txt
@@ -2218,6 +2218,7 @@
                     "大正",
                     "昭和",
                     "平成",
+                    "令和",
                 }
                 narrow{
                     "大化",
@@ -2456,6 +2457,7 @@
                     "T",
                     "S",
                     "H",
+                    "R",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/ko.txt b/icu4c/source/data/locales/ko.txt
index 2aa5052..b01b080 100644
--- a/icu4c/source/data/locales/ko.txt
+++ b/icu4c/source/data/locales/ko.txt
@@ -1360,6 +1360,7 @@
                     "다이쇼",
                     "쇼와",
                     "헤이세이",
+                    "레이와",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/lo.txt b/icu4c/source/data/locales/lo.txt
index d2e3eb9..18b0b67 100755
--- a/icu4c/source/data/locales/lo.txt
+++ b/icu4c/source/data/locales/lo.txt
@@ -1692,6 +1692,7 @@
                     "ໄຕໂຊ",
                     "ໂຊວາ",
                     "ຮີຊີ",
+                    "Reiwa",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/nl.txt b/icu4c/source/data/locales/nl.txt
index 0b1dfb5..3139ee5 100644
--- a/icu4c/source/data/locales/nl.txt
+++ b/icu4c/source/data/locales/nl.txt
@@ -1896,6 +1896,7 @@
                     "Taishō",
                     "Shōwa",
                     "Heisei",
+                    "Reiwa",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/root.txt b/icu4c/source/data/locales/root.txt
index c31d252..3d0a732 100644
--- a/icu4c/source/data/locales/root.txt
+++ b/icu4c/source/data/locales/root.txt
@@ -1651,6 +1651,7 @@
                     "Taishō",
                     "Shōwa",
                     "Heisei",
+                    "Reiwa",
                 }
                 narrow{
                     "Taika (645-650)",
@@ -1889,6 +1890,7 @@
                     "T",
                     "S",
                     "H",
+                    "R",
                 }
                 wide:alias{"/LOCALE/calendar/japanese/eras/abbreviated"}
             }
diff --git a/icu4c/source/data/locales/ru.txt b/icu4c/source/data/locales/ru.txt
index b167322..b622ca6 100644
--- a/icu4c/source/data/locales/ru.txt
+++ b/icu4c/source/data/locales/ru.txt
@@ -1502,6 +1502,7 @@
                     "Эпоха Тайсьо",
                     "Сьова",
                     "Эпоха Хэйсэй",
+                    "Рэйва",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/sr.txt b/icu4c/source/data/locales/sr.txt
index 139bd1a..24a0378 100644
--- a/icu4c/source/data/locales/sr.txt
+++ b/icu4c/source/data/locales/sr.txt
@@ -1093,6 +1093,7 @@
                     "Таишо",
                     "Шова",
                     "Хаисеи",
+                    "Реива",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/sr_Latn.txt b/icu4c/source/data/locales/sr_Latn.txt
index e99b6e4..574b01d 100644
--- a/icu4c/source/data/locales/sr_Latn.txt
+++ b/icu4c/source/data/locales/sr_Latn.txt
@@ -1094,6 +1094,7 @@
                     "Taišo",
                     "Šova",
                     "Haisei",
+                    "Reiva",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/sv.txt b/icu4c/source/data/locales/sv.txt
index b0216a2..6541139 100644
--- a/icu4c/source/data/locales/sv.txt
+++ b/icu4c/source/data/locales/sv.txt
@@ -1343,6 +1343,7 @@
                     "Taishō",
                     "Shōwa",
                     "Heisei",
+                    "Reiwa",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/th.txt b/icu4c/source/data/locales/th.txt
index dbb30ab..4a7d1e7 100644
--- a/icu4c/source/data/locales/th.txt
+++ b/icu4c/source/data/locales/th.txt
@@ -2028,6 +2028,7 @@
                     "ทะอิโช",
                     "โชวะ",
                     "เฮเซ",
+                    "เรวะ",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/zh.txt b/icu4c/source/data/locales/zh.txt
index 392df0a..a39f1da 100644
--- a/icu4c/source/data/locales/zh.txt
+++ b/icu4c/source/data/locales/zh.txt
@@ -1906,6 +1906,7 @@
                     "大正",
                     "昭和",
                     "平成",
+                    "令和",
                 }
             }
         }
diff --git a/icu4c/source/data/locales/zh_Hant.txt b/icu4c/source/data/locales/zh_Hant.txt
index 6e0d17e..cbc2ed9 100644
--- a/icu4c/source/data/locales/zh_Hant.txt
+++ b/icu4c/source/data/locales/zh_Hant.txt
@@ -2157,6 +2157,7 @@
                     "大正",
                     "昭和",
                     "平成",
+                    "令和",
                 }
             }
         }
diff --git a/icu4c/source/i18n/japancal.cpp b/icu4c/source/i18n/japancal.cpp
index 0f985f0..7886185 100644
--- a/icu4c/source/i18n/japancal.cpp
+++ b/icu4c/source/i18n/japancal.cpp
@@ -273,7 +273,8 @@
     {  1868,    9,  8 },   // Meiji    232
     {  1912,    7, 30 },   // Taisho   233
     {  1926,   12, 25 },   // Showa    234
-    {  1989,    1,  8 }   // Heisei    235
+    {  1989,    1,  8 },   // Heisei   235
+    {  2019,    5,  1 }    // Reiwa    236
 };
 
 #define kEraCount (sizeof(kEraInfo)/sizeof(kEraInfo[0]))
diff --git a/icu4c/source/test/intltest/incaltst.cpp b/icu4c/source/test/intltest/incaltst.cpp
index 7627696..b1db658 100644
--- a/icu4c/source/test/intltest/incaltst.cpp
+++ b/icu4c/source/test/intltest/incaltst.cpp
@@ -75,6 +75,7 @@
     CASE(7,TestPersian);
     CASE(8,TestPersianFormat);
     CASE(9,TestTaiwan);
+    CASE(10,TestJapaneseHeiseiToReiwa);
     default: name = ""; break;
     }
 }
@@ -624,23 +625,23 @@
         // Test simple parse/format with adopt
         UDate aDate = 0; 
         
-        // Test parse with missing era (should default to current era, heisei)
+        // Test parse with missing era (should default to current era)
         // Test parse with incomplete information
         logln("Testing parse w/ missing era...");
-        SimpleDateFormat *fmt = new SimpleDateFormat(UnicodeString("y.M.d"), Locale("ja_JP@calendar=japanese"), status);
+        SimpleDateFormat *fmt = new SimpleDateFormat(UnicodeString("y/M/d"), Locale("ja_JP@calendar=japanese"), status);
         CHECK(status, "creating date format instance");
         if(!fmt) { 
             errln("Coudln't create en_US instance");
         } else {
             UErrorCode s2 = U_ZERO_ERROR;
             cal2->clear();
-            UnicodeString samplestr("1.1.9");
+            UnicodeString samplestr("1/5/9");
             logln(UnicodeString() + "Test Year: " + samplestr);
             aDate = fmt->parse(samplestr, s2);
             ParsePosition pp=0;
             fmt->parse(samplestr, *cal2, pp);
-            CHECK(s2, "parsing the 1.1.9 string");
-            logln("*cal2 after 119 parse:");
+            CHECK(s2, "parsing the 1/5/9 string");
+            logln("*cal2 after 159 parse:");
             str.remove();
             fmt2->format(aDate, str);
             logln(UnicodeString() + "as Gregorian Calendar: " + str);
@@ -651,7 +652,7 @@
             int32_t expectYear = 1;
             int32_t expectEra = JapaneseCalendar::getCurrentEra();
             if((gotYear!=1) || (gotEra != expectEra)) {
-                errln(UnicodeString("parse "+samplestr+" of 'y.m.d' as Japanese Calendar, expected year ") + expectYear + 
+                errln(UnicodeString("parse "+samplestr+" of 'y/m/d' as Japanese Calendar, expected year ") + expectYear + 
                     UnicodeString(" and era ") + expectEra +", but got year " + gotYear + " and era " + gotEra + " (Gregorian:" + str +")");
             } else {            
                 logln(UnicodeString() + " year: " + gotYear + ", era: " + gotEra);
@@ -664,7 +665,7 @@
         // Test simple parse/format with adopt
         UDate aDate = 0; 
         
-        // Test parse with missing era (should default to current era, heisei)
+        // Test parse with missing era (should default to current era)
         // Test parse with incomplete information
         logln("Testing parse w/ just year...");
         SimpleDateFormat *fmt = new SimpleDateFormat(UnicodeString("y"), Locale("ja_JP@calendar=japanese"), status);
@@ -676,7 +677,7 @@
             cal2->clear();
             UnicodeString samplestr("1");
             logln(UnicodeString() + "Test Year: " + samplestr);
-            aDate = fmt->parse(samplestr, s2);
+            aDate = fmt->parse(samplestr, s2);  // Should be parsed as the first day of the current era
             ParsePosition pp=0;
             fmt->parse(samplestr, *cal2, pp);
             CHECK(s2, "parsing the 1 string");
@@ -689,7 +690,7 @@
             int32_t gotYear = cal2->get(UCAL_YEAR, s2);
             int32_t gotEra = cal2->get(UCAL_ERA, s2);
             int32_t expectYear = 1;
-            int32_t expectEra = 235; //JapaneseCalendar::kCurrentEra;
+            int32_t expectEra = JapaneseCalendar::getCurrentEra();
             if((gotYear!=1) || (gotEra != expectEra)) {
                 errln(UnicodeString("parse "+samplestr+" of 'y' as Japanese Calendar, expected year ") + expectYear + 
                     UnicodeString(" and era ") + expectEra +", but got year " + gotYear + " and era " + gotEra + " (Gregorian:" + str +")");
@@ -698,13 +699,47 @@
             }
             delete fmt;
         }
-    }    
+    }
 
     delete cal2;
     delete cal;
     delete fmt2;
 }
 
+void IntlCalendarTest::TestJapaneseHeiseiToReiwa() {
+    Calendar *cal;
+    UErrorCode status = U_ZERO_ERROR;
+    cal = Calendar::createInstance(status);
+    CHECK(status, UnicodeString("Creating default Gregorian Calendar"));
+    cal->set(2019, UCAL_APRIL, 29);
+
+    DateFormat *jfmt = DateFormat::createDateInstance(DateFormat::LONG, "ja@calendar=japanese");
+    CHECK(status, UnicodeString("Creating date format ja@calendar=japanese"))
+
+    const char* EXPECTED_FORMAT[4] = {
+        "\\u5E73\\u621031\\u5E744\\u670829\\u65E5", // Heisei 31 April 29
+        "\\u5E73\\u621031\\u5E744\\u670830\\u65E5", // Heisei 31 April 30
+        "\\u4EE4\\u548c1\\u5E745\\u67081\\u65E5",   // Reiwa 1 May 1
+        "\\u4EE4\\u548c1\\u5E745\\u67082\\u65E5"    // Reiwa 1 May 2
+    };
+
+    for (int32_t i = 0; i < 4; i++) {
+        UnicodeString dateStr;
+        UDate d = cal->getTime(status);
+        CHECK(status, UnicodeString("Get test date"));
+        jfmt->format(d, dateStr);
+        UnicodeString expected(UnicodeString(EXPECTED_FORMAT[i], -1, US_INV).unescape());
+        if (expected.compare(dateStr) != 0) {
+            errln(UnicodeString("Formatting year:") + cal->get(UCAL_YEAR, status) + " month:"
+                + cal->get(UCAL_MONTH, status) + " day:" + (cal->get(UCAL_DATE, status) + 1)
+                + " - expected: " + expected + " / actual: " + dateStr);
+        }
+        cal->add(UCAL_DATE, 1, status);
+        CHECK(status, UnicodeString("Add 1 day"));
+    }
+    delete jfmt;
+    delete cal;
+}
 
 
 
diff --git a/icu4c/source/test/intltest/incaltst.h b/icu4c/source/test/intltest/incaltst.h
index 2c03ce3..45d6727 100644
--- a/icu4c/source/test/intltest/incaltst.h
+++ b/icu4c/source/test/intltest/incaltst.h
@@ -32,7 +32,8 @@
     void TestJapanese(void);
     void TestJapaneseFormat(void);
     void TestJapanese3860(void);
-    
+    void TestJapaneseHeiseiToReiwa(void);
+
     void TestPersian(void);
     void TestPersianFormat(void);
 
diff --git a/icu4c/source/test/testdata/format.txt b/icu4c/source/test/testdata/format.txt
index e999cfd..31b78b4 100644
--- a/icu4c/source/test/testdata/format.txt
+++ b/icu4c/source/test/testdata/format.txt
@@ -492,35 +492,35 @@
                     "",
                     "PATTERN=G y",
                     "YEAR=8",
-                    "Heisei 8"
+                    "Reiwa 8"
                },
                {
                     "en_US@calendar=japanese",         
                     "",
                     "PATTERN=G yy",
                     "YEAR=8",
-                    "Heisei 08"
+                    "Reiwa 08"
                },
                {
                     "en_US@calendar=japanese",         
                     "",
                     "PATTERN=G yyy",
                     "YEAR=8",
-                    "Heisei 008"
+                    "Reiwa 008"
                },
                {
                     "en_US@calendar=japanese",         
                     "",
                     "PATTERN=G yyyy",
                     "YEAR=8",
-                    "Heisei 0008"
+                    "Reiwa 0008"
                },
                {
                     "en_US@calendar=japanese",         
                     "",
                     "PATTERN=G yyyyy",
                     "YEAR=8",
-                    "Heisei 00008"
+                    "Reiwa 00008"
                },
 
             }
diff --git a/icu4c/source/test/testdata/structLocale.txt b/icu4c/source/test/testdata/structLocale.txt
index ae6b52e..81058f0 100644
--- a/icu4c/source/test/testdata/structLocale.txt
+++ b/icu4c/source/test/testdata/structLocale.txt
@@ -16819,6 +16819,7 @@
                     "",
                     "",
                     "",
+                    "",
                 }
                 wide{
                     "",
@@ -17057,6 +17058,7 @@
                     "",
                     "",
                     "",
+                    "",
                 }
                 narrow{
                     "",
@@ -17295,6 +17297,7 @@
                     "",
                     "",
                     "",
+                    "",
                 }
             }
         }