WordCountReducer(1).java

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

import org.apache.hadoop.io.*;
import org.apache.hadoop.mapred.*;

public class WordCountReducer extends MapReduceBase implements Reducer<Text, IntWritable, Text, IntWritable>
{
      //reduce method accepts the Key Value pairs from mappers, do the aggregation based on keys and produce the final out put
      public void reduce(Text key, Iterator<IntWritable> values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException
      {
            int sum = 0;
            /*iterates through all the values available with a key and add them together and give the
            final result as the key and sum of its values*/
          while (values.hasNext())
          {
               sum += values.next().get();
          }
          output.collect(key, new IntWritable(sum));
      }
}