org.apache.hadoop.mapred
Interface RecordReader

All Known Implementing Classes:

KeyValueLineRecordReader, LineRecordReader, SequenceFileAsTextRecordReader, SequenceFileRecordReader, StreamBaseRecordReader, StreamLineRecordReader, StreamSequenceRecordReader, StreamXmlRecordReader

public interface RecordReader

Reads key/value pairs from an input file FileSplit. Implemented by InputFormat implementations.

Method Summary

void	close() Close this to future operations.
WritableComparable	createKey() Create an object of the appropriate type to be used as a key.
Writable	createValue() Create an object of the appropriate type to be used as the value.
long	getPos() Returns the current position in the input.
float	getProgress() How far has the reader gone through the input.
boolean	next(Writable key, Writable value) Reads the next key/value pair.

Method Detail

next

boolean next(Writable key,
             Writable value)
             throws IOException

Reads the next key/value pair.

Parameters:

key - the key to read data into

value - the value to read data into

Returns:

true iff a key/value was read, false if at EOF

Throws:

IOException

See Also:

Writable.readFields(DataInput)

createKey

WritableComparable createKey()

Create an object of the appropriate type to be used as a key.

Returns:

a new key object

createValue

Writable createValue()

Create an object of the appropriate type to be used as the value.

Returns:

a new value object

getPos

long getPos()
            throws IOException

Returns the current position in the input.

Throws:

IOException

close

void close()
           throws IOException

Close this to future operations.

Throws:

IOException

getProgress

float getProgress()
                  throws IOException

How far has the reader gone through the input.

Returns:

progress from 0.0 to 1.0

Throws:

IOException