File Stream (HDFS & Local FS)

HDFS and Local FileStream for ARFF files. 
E.g.:
1) From 1 HDFS file:
PrequentialEvaluation ... -s (com.yahoo.labs.samoa.streams.ArffFileStream -s com.yahoo.labs.samoa.streams.fs.HDFSFileStreamSource -f /samoa/parts/part1.arff)
2) From HDFS directory:
PrequentialEvaluation ... -s (com.yahoo.labs.samoa.streams.ArffFileStream -s com.yahoo.labs.samoa.streams.fs.HDFSFileStreamSource -f /samoa/parts)
3) From Local file:
PrequentialEvaluation ... -s (com.yahoo.labs.samoa.streams.ArffFileStream -s com.yahoo.labs.samoa.streams.fs.LocalFileStreamSource -f ~/samoa/parts/part1.arff)
4) From Local file:
PrequentialEvaluation ... -s (com.yahoo.labs.samoa.streams.ArffFileStream -s com.yahoo.labs.samoa.streams.fs.LocalFileStreamSource -f ~/samoa/parts)
Do we need the "." (dot)?
What if we have files without extension?