[NO ISSUE] Factor out date formatting

- user model changes: no
- storage format changes: no
- interface changes: no

Change-Id: Id0b723865141bb7eecf87830537d8310bfe2a5d3
Reviewed-on: https://asterix-gerrit.ics.uci.edu/3144
Sonar-Qube: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Contrib: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Murtadha Hubail <mhubail@apache.org>
diff --git a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/base/ADateTime.java b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/base/ADateTime.java
index 62e5c87..df38d1c 100644
--- a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/base/ADateTime.java
+++ b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/base/ADateTime.java
@@ -106,24 +106,18 @@
 
     @Override
     public String toString() {
-        StringBuilder sbder = new StringBuilder();
-        sbder.append("datetime: { ");
-        try {
-            GregorianCalendarSystem.getInstance().getExtendStringRepUntilField(chrononTime, 0, sbder,
-                    GregorianCalendarSystem.Fields.YEAR, GregorianCalendarSystem.Fields.MILLISECOND, true);
-        } catch (IOException e) {
-            throw new RuntimeException(e);
-        }
-        sbder.append(" }");
-        return sbder.toString();
+        return appendDatetime(new StringBuilder().append("datetime: { "), chrononTime).append(" }").toString();
     }
 
     public String toSimpleString() {
-        StringBuilder sbder = new StringBuilder();
+        return appendDatetime(new StringBuilder(), chrononTime).toString();
+    }
+
+    private static StringBuilder appendDatetime(StringBuilder sbder, long chrononTime) {
         try {
             GregorianCalendarSystem.getInstance().getExtendStringRepUntilField(chrononTime, 0, sbder,
                     GregorianCalendarSystem.Fields.YEAR, GregorianCalendarSystem.Fields.MILLISECOND, true);
-            return sbder.toString();
+            return sbder;
         } catch (IOException e) {
             throw new IllegalStateException(e);
         }