From 091464430b0639ca56743eed564bd785c08d52e1 Mon Sep 17 00:00:00 2001
From: Yoshito Umaoka <y.umaoka@gmail.com>
Date: Thu, 9 Aug 2012 21:37:41 +0000
Subject: [PATCH] ICU-9452 Fixed calendar addition issue with the Samoa Dec
 2011 24 hour transition (ICU4J)

X-SVN-Rev: 32142
---
 .../core/src/com/ibm/icu/util/Calendar.java   | 16 ++++++---
 .../dev/test/calendar/CalendarRegression.java | 34 +++++++++++++++++++
 2 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/icu4j/main/classes/core/src/com/ibm/icu/util/Calendar.java b/icu4j/main/classes/core/src/com/ibm/icu/util/Calendar.java
index a20f4f5a645..9d9bbef069f 100644
--- a/icu4j/main/classes/core/src/com/ibm/icu/util/Calendar.java
+++ b/icu4j/main/classes/core/src/com/ibm/icu/util/Calendar.java
@@ -3265,10 +3265,18 @@ public abstract class Calendar implements Serializable, Cloneable, Comparable<Ca
                 // danger of adjusting into a different day. To avoid
                 // this we make the adjustment only if it actually
                 // maintains the hour.
-                long t = time;
-                setTimeInMillis(time + prevOffset - newOffset);
-                if (get(HOUR_OF_DAY) != hour) {
-                    setTimeInMillis(t);
+
+                // When the difference of the previous UTC offset and
+                // the new UTC offset exceeds 1 full day, we do not want
+                // to roll over/back the date. For now, this only happens
+                // in Samoa (Pacific/Apia) on Dec 30, 2011. See ticket:9452.
+                long adjAmount = (prevOffset - newOffset) % ONE_DAY;
+                if (adjAmount != 0) {
+                    long t = time;
+                    setTimeInMillis(time + adjAmount);
+                    if (get(HOUR_OF_DAY) != hour) {
+                        setTimeInMillis(t);
+                    }
                 }
             }
         }
diff --git a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/CalendarRegression.java b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/CalendarRegression.java
index 4f9a9012de1..eef99f7e123 100644
--- a/icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/CalendarRegression.java
+++ b/icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/CalendarRegression.java
@@ -2261,6 +2261,40 @@ public class CalendarRegression extends com.ibm.icu.dev.test.TestFmwk {
             logln("Pass: rolled calendar is " + cal1.getTime());
         }
     }
+
+    /**
+     * Test case for ticket 9452
+     * Calendar addition fall onto the missing date - 2011-12-30 in Samoa
+     */
+    public void TestT9452() {
+        TimeZone samoaTZ = TimeZone.getTimeZone("Pacific/Apia");
+        GregorianCalendar cal = new GregorianCalendar(samoaTZ);
+
+        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZZZZZ");
+        sdf.setTimeZone(samoaTZ);
+
+        // Set date to 2011-12-29 00:00
+        cal.clear();
+        cal.set(2011, Calendar.DECEMBER, 29, 0, 0, 0);
+
+        Date d = cal.getTime();
+        String dstr = sdf.format(d);
+        logln("Initial date: " + dstr);
+
+        // Add 1 day
+        cal.add(Calendar.DATE, 1);
+        d = cal.getTime();
+        dstr = sdf.format(d);
+        logln("+1 day: " + dstr);
+        assertEquals("Add 1 day", "2011-12-31T00:00:00+14:00", dstr);
+
+        // Subtract 1 day
+        cal.add(Calendar.DATE, -1);
+        d = cal.getTime();
+        dstr = sdf.format(d);
+        logln("-1 day: " + dstr);
+        assertEquals("Subtract 1 day", "2011-12-29T00:00:00-10:00", dstr);
+    }
 }
 
 //eof