org.apache.hadoop.mapreduce.lib.input

Class KeyValueLineRecordReader

java.lang.Object

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

org.apache.hadoop.mapreduce.lib.input.KeyValueLineRecordReader

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class KeyValueLineRecordReader
extends 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 conf)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Close the record reader.
static int	findSeparator(byte[] utf, int start, int length, byte sep)
org.apache.hadoop.io.Text	getCurrentKey() Get the current key
org.apache.hadoop.io.Text	getCurrentValue() Get the current value.
java.lang.Class<?>	getKeyClass()
float	getProgress() The current progress of the record reader through its data.
void	initialize(InputSplit genericSplit, TaskAttemptContext context) Called once at initialization.
boolean	nextKeyValue() Read key/value pair in a line.
static void	setKeyValue(org.apache.hadoop.io.Text key, org.apache.hadoop.io.Text value, byte[] line, int lineLen, int pos)

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 conf)
                         throws java.io.IOException

Throws:

java.io.IOException

Method Detail

getKeyClass

public java.lang.Class<?> getKeyClass()

initialize

public void initialize(InputSplit genericSplit,
              TaskAttemptContext context)
                throws java.io.IOException

Description copied from class: RecordReader

Called once at initialization.

Specified by:

initialize in class RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Parameters:

genericSplit - the split that defines the range of records to read

context - the information about the task

Throws:

java.io.IOException

findSeparator

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

setKeyValue

public static void setKeyValue(org.apache.hadoop.io.Text key,
               org.apache.hadoop.io.Text value,
               byte[] line,
               int lineLen,
               int pos)

nextKeyValue

public boolean nextKeyValue()
                     throws java.io.IOException

Read key/value pair in a line.

Specified by:

nextKeyValue in class RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

true if a key/value pair was read

Throws:

java.io.IOException

getCurrentKey

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

Description copied from class: RecordReader

Get the current key

Specified by:

getCurrentKey in class RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

the current key or null if there is no current key

getCurrentValue

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

Description copied from class: RecordReader

Get the current value.

Specified by:

getCurrentValue in class RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Returns:

the object that was read

getProgress

public float getProgress()

Description copied from class: RecordReader

The current progress of the record reader through its data.

Specified by:

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

Returns:

a number between 0.0 and 1.0 that is the fraction of the data read

close

public void close()
           throws java.io.IOException

Description copied from class: RecordReader

Close the record reader.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

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

Throws:

java.io.IOException