fixes #208: NPE when retrieving logs for empty room

changelog.html

@@ -52,6 +52,7 @@ <h1>
     <li>[<a href='https://github.com/igniterealtime/openfire-monitoring-plugin/issues/192'>Issue #192</a>] - Combining keyword and participant(s) makes search fail</li>
     <li>[<a href='https://github.com/igniterealtime/openfire-monitoring-plugin/issues/195'>Issue #195</a>] - Class incompatibility with latest OF MUC</li>
     <li>[<a href='https://github.com/igniterealtime/openfire-monitoring-plugin/issues/200'>Issue #200</a>] - Remove references to deprecated logger methods</li>
+    <li>[<a href='https://github.com/igniterealtime/openfire-monitoring-plugin/issues/208'>Issue #208</a>] - Prevent NullPointerException when retrieving logs for empty room</li>
     <li>[<a href='https://github.com/igniterealtime/openfire-monitoring-plugin/issues/210'>Issue #210</a>] - Update Jersey library to 2.35</li>
 </ul>
 

src/java/com/reucon/openfire/plugin/archive/impl/MucMamPersistenceManager.java

@@ -392,7 +392,13 @@ public static Instant getDateOfFirstLog( MUCRoom room )
             }
             rs = pstmt.executeQuery();
             if (rs.next()) {
-                return new Date(Long.parseLong(rs.getString(1).trim())).toInstant();
+                // Note that 'min()' will return a single 'null' value if the 'where' condition does not match.
+                final String minValue = rs.getString(1);
+                if (minValue == null || rs.wasNull()) {
+                    return null;
+                } else {
+                    return new Date(Long.parseLong(minValue.trim())).toInstant();
+                }
             }
         } catch (SQLException e) {
             Log.error("SQL failure while trying to find the timestamp of the earliest message for room {} in MAM-MUC: ", room.getJID(), e);