Null values in Date field only when RDD is saved as File.

[Manas Kar]

Hi,
 I am using a library that parses Ais Messages. My code which follows the
simple steps gives me null values in Date field.

1) Get the message from file.
2) parse the message.
3) map the message RDD to only keep the (Date, SomeInfo)
4) take top 100 element.
Result = the Date field appears fine on the screen

5) save the tuple RDD(created at step 4) to HDFS using SaveAsTextFile.
Result = When I check the saved File all my Date fields are Null.

Please guide me in the right direction.