WordCountReducer.java

package sdz.hadoop.wordcount;

import java.io.IOException;
import java.util.Iterator;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;

import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;

import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.mapreduce.Reducer;

import java.util.StringTokenizer;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class WordCountReducer extends Reducer<Text, IntWritable, Text, IntWritable> {

    private IntWritable totalWordCount = new IntWritable();

    @Override
    public void reduce(final Text key, final Iterable<IntWritable> values, 
    final Context context) throws IOException, InterruptedException {
        int sum = 0;
        Iterator<IntWritable> iterator = values.iterator();

        while (iterator.hasNext()) {
            sum += iterator.next().get();
        }

        totalWordCount.set(sum);
        context.write(key, totalWordCount);
    }
}