org.apache.hadoop.mapred.LineRecordReader has 3 constructors.

The one in the following is used normally.

public LineRecordReader(Configuration job,  FileSplit split) throws
IOException

But when the following ones are used?  I commented them and re-compiled the
code without errors.  So probably they are not used directly in Hadoop core
code.
But then why are they there in the code?
public LineRecordReader(InputStream in, long offset, long endOffset, int
maxLineLength)
public LineRecordReader(InputStream in, long offset, long endOffset,
Configuration job)
Thanks,
Abdul Qadeer