Java NullPointerException when traversing a non-null recordset

output.print(rs.getString(1));

preparedStatement.setLong(1, primaryKey);
ResultSet rs = preparedStatement.executeQuery();
while (rs.next())
{
  String foo = rs.getString(1);
  if (foo != null)
    ...
}

while (rs.next()){
    try{
        output.write(rs.getDate(2) + " " + timeFormat.format(rs.getTime(2)) + "|");
        ....
    }
    catch(IOException e){//error handling code}
}

Exception in thread "main" java.lang.NullPointerException
at com.sybase.jdbc3.timedio.RawDbio.reallyRead(Unknown Source)
at com.sybase.jdbc3.timedio.Dbio.doRead(Unknown Source)
at com.sybase.jdbc3.timedio.InStreamMgr.a(Unknown Source)
at com.sybase.jdbc3.timedio.InStreamMgr.doRead(Unknown Source)
at com.sybase.jdbc3.tds.TdsProtocolContext.getChunk(Unknown Source)
at com.sybase.jdbc3.tds.PduInputFormatter.a(Unknown Source)
at com.sybase.jdbc3.tds.PduInputFormatter.read(Unknown Source)
at com.sybase.jdbc3.tds.TdsInputStream.read(Unknown Source)
at com.sybase.jdbc3.utils.CacheStream.read(Unknown Source)
at com.sybase.jdbc3.tds.TdsInputStream.read(Unknown Source)
at com.sybase.jdbc3.tds.TdsInputStream.readInt(Unknown Source)
at com.sybase.jdbc3.tds.TdsDataObject.readDATETIMN(Unknown Source)
at com.sybase.jdbc3.tds.TdsJdbcInputStream.getDateObject(Unknown Source)
at com.sybase.jdbc3.jdbc.SybResultSet.getDate(Unknown Source)
at <removed>.processResults(ProcessRecords.java:118)
at <removed>.Main.main(Main.java:65)