CLDR-10347 show one example for each day period, excluding midnight

tools/cldr-code/src/main/java/org/unicode/cldr/test/ExampleGenerator.java

@@ -2597,7 +2597,6 @@ private String handleDateFormatItem(String xpath, String value, boolean showCont
                 String numbersOverride = parts.findAttributeValue("pattern", "numbers");
                 SimpleDateFormat sdf =
                         icuServiceBuilder.getDateFormat(calendar, value, numbersOverride);
-                sdf.setTimeZone(ZONE_SAMPLE);
                 String defaultNumberingSystem =
                         cldrFile.getWinningValue("//ldml/numbers/defaultNumberingSystem");
                 String timeSeparator =
@@ -2609,6 +2608,7 @@ private String handleDateFormatItem(String xpath, String value, boolean showCont
                 dfs.setTimeSeparatorString(timeSeparator);
                 sdf.setDateFormatSymbols(dfs);
                 if (id == null || id.indexOf('B') < 0) {
+                    sdf.setTimeZone(ZONE_SAMPLE);
                     // Standard date/time format, or availableFormat without dayPeriod
                     if (value.contains("MMM") || value.contains("LLL")) {
                         // alpha month, do not need context examples
@@ -2626,9 +2626,19 @@ private String handleDateFormatItem(String xpath, String value, boolean showCont
                     }
                 } else {
                     List<String> examples = new ArrayList<>();
-                    examples.add(sdf.format(DATE_SAMPLE3));
-                    examples.add(sdf.format(DATE_SAMPLE));
-                    examples.add(sdf.format(DATE_SAMPLE4));
+                    DayPeriodInfo dayPeriodInfo = supplementalDataInfo.getDayPeriods(DayPeriodInfo.Type.format, cldrFile.getLocaleID());
+                    Set<DayPeriod> dayPeriods = new LinkedHashSet<DayPeriod>(dayPeriodInfo.getPeriods());
+                    for (DayPeriod dayPeriod : dayPeriods) {
+                        if (dayPeriod.equals(DayPeriod.midnight)) { // suppress midnight, see ICU-12278 bug
+                            continue;
+                        }
+                        R3<Integer, Integer, Boolean> info = dayPeriodInfo.getFirstDayPeriodInfo(dayPeriod);
+                        if (info != null) {
+                            int time = ((info.get0() + info.get1()) / 2); // time midpoint 
+                            String formatted = sdf.format(time);                      
+                            examples.add(formatted);
+                        }
+                    }
                     return formatExampleList(examples.toArray(new String[0]));
                 }
             }

tools/cldr-code/src/test/java/org/unicode/cldr/unittest/TestExampleGenerator.java

@@ -1123,6 +1123,56 @@ private void checkDayPeriod(
         checkPathValue(exampleGenerator, path, cldrFile.getStringValue(path), expected);
     }
 
+    public void TestAllDayPeriods() { 
+        // excludes midnight, see ICU-12278 
+        String[][] tests = {
+            {
+                "en",
+                "//ldml/dates/calendars/calendar"
+                        + "[@type=\"gregorian\"]/dateTimeFormats/"
+                        + "availableFormats/dateFormatItem"
+                        + "[@id=\"Bhm\"]",
+                "en day periods pattern \"Bhm\"",
+                "〖3:00 at night〗〖9:00 in the morning〗〖12:00 noon〗〖3:00 in the afternoon〗〖7:30 in the evening〗"
+            },
+            {
+                "it",
+                "//ldml/dates/calendars/calendar"
+                        + "[@type=\"gregorian\"]/dateTimeFormats/"
+                        + "availableFormats/dateFormatItem"
+                        + "[@id=\"Bhm\"]",
+                "it day periods pattern \"Bhm\"",
+                "〖3:00 di notte〗〖9:00 di mattina〗〖12:00 mezzogiorno〗〖3:00 di pomeriggio〗〖9:00 di sera〗"
+            }, 
+            {
+                "de",
+                "//ldml/dates/calendars/calendar"
+                        + "[@type=\"gregorian\"]/dateTimeFormats/"
+                        + "availableFormats/dateFormatItem"
+                        + "[@id=\"Bhm\"]",
+                "de day periods pattern \"Bhm\"",
+                "〖2:30 nachts〗〖7:30 morgens〗〖11:00 vorm.〗〖12:30 mittags〗〖3:30 nachm.〗〖9:00 abends〗"
+            },
+            {
+                "zh",
+                "//ldml/dates/calendars/calendar"
+                        + "[@type=\"gregorian\"]/dateTimeFormats/"
+                        + "availableFormats/dateFormatItem"
+                        + "[@id=\"Bhm\"]",
+                "zh day periods pattern \"Bhm\"",
+                "〖凌晨2:30〗〖早上6:30〗〖上午10:00〗〖中午12:30〗〖下午4:00〗〖晚上9:30〗"
+            },
+        };
+        for (String[] test : tests) {
+            final String locale = test[0];
+            final String path = test[1];
+            final String message = test[2];
+            final String expected = test[3];
+            ExampleGenerator exampleGenerator = getExampleGenerator(locale);
+            checkValue(message, expected, exampleGenerator, path);
+        }
+    }
+
     /**
      * Test that getExampleHtml returns same output for same input regardless of order in which it
      * is called with different inputs.