org.apache.hadoop.examples
Class WordCount

java.lang.Object
  org.apache.hadoop.conf.Configured
      org.apache.hadoop.examples.WordCount

All Implemented Interfaces:

Configurable, Tool

public class WordCount
extends Configured
implements Tool

This is an example Hadoop Map/Reduce application. It reads the text input files, breaks each line into words and counts them. The output is a locally sorted list of words and the count of how often they occurred. To run: bin/hadoop jar build/hadoop-examples.jar wordcount [-m maps] [-r reduces] in-dir out-dir

Nested Class Summary

static class	WordCount.MapClass Counts the words in each line.
static class	WordCount.Reduce A reducer class that just emits the sum of the input values.

Constructor Summary

WordCount()

Method Summary

static void	main(String[] args)
int	run(String[] args) The main driver for word count map/reduce program.

Methods inherited from class org.apache.hadoop.conf.Configured

getConf, setConf

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.conf.Configurable

getConf, setConf

Constructor Detail

WordCount

public WordCount()

Method Detail

run

public int run(String[] args)
        throws Exception

The main driver for word count map/reduce program. Invoke this method to submit the map/reduce job.

Specified by:

run in interface Tool

Parameters:

args - command specific arguments.

Returns:

exit code.

Throws:

IOException - When there is communication problems with the job tracker.

Exception

main

public static void main(String[] args)
                 throws Exception

Throws:

Exception