org.apache.hadoop.mapred

Class KeyValueLineRecordReader

java.lang.Object

org.apache.hadoop.mapred.KeyValueLineRecordReader

All Implemented Interfaces:

RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

public class KeyValueLineRecordReader
extends java.lang.Object
implements RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

This class treats a line in the input as a key/value pair separated by a separator character. The separator can be specified in config file under the attribute name key.value.separator.in.input.line. The default separator is the tab character ('\t').

Constructor Summary

Constructors

Constructor and Description
KeyValueLineRecordReader(org.apache.hadoop.conf.Configuration job, FileSplit split)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Close this InputSplit to future operations.
org.apache.hadoop.io.Text	createKey() Create an object of the appropriate type to be used as a key.
org.apache.hadoop.io.Text	createValue() Create an object of the appropriate type to be used as a value.
static int	findSeparator(byte[] utf, int start, int length, byte sep)
java.lang.Class	getKeyClass()
long	getPos() Returns the current position in the input.
float	getProgress() How much of the input has the RecordReader consumed i.e.
boolean	next(org.apache.hadoop.io.Text key, org.apache.hadoop.io.Text value) Read key/value pair in a line.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

KeyValueLineRecordReader

public KeyValueLineRecordReader(org.apache.hadoop.conf.Configuration job,
                        FileSplit split)
                         throws java.io.IOException

Throws:

java.io.IOException

Method Detail

getKeyClass

public java.lang.Class getKeyClass()

createKey

public org.apache.hadoop.io.Text createKey()

Description copied from interface: RecordReader

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

Specified by:

createKey in interface RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

a new key object.

createValue

public org.apache.hadoop.io.Text createValue()

Description copied from interface: RecordReader

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

Specified by:

createValue in interface RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

a new value object.

findSeparator

public static int findSeparator(byte[] utf,
                int start,
                int length,
                byte sep)

next

public boolean next(org.apache.hadoop.io.Text key,
           org.apache.hadoop.io.Text value)
             throws java.io.IOException

Read key/value pair in a line.

Specified by:

next in interface RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

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:

java.io.IOException

getProgress

public float getProgress()

Description copied from interface: RecordReader

How much of the input has the RecordReader consumed i.e. has been processed by?

Specified by:

getProgress in interface RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

progress from 0.0 to 1.0.

getPos

public long getPos()
            throws java.io.IOException

Description copied from interface: RecordReader

Returns the current position in the input.

Specified by:

getPos in interface RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

the current position in the input.

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Description copied from interface: RecordReader

Close this InputSplit to future operations.

Specified by:

close in interface RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

java.io.IOException