[Hadoop-common-user] why my Reduce Class does not work?

You need @Override on your reduce method. Right now you are getting
the identity reduce method.

Thank you very much Ken,


The problem was with missing Generic declaration
(Eclipse failed to override the method and I didn't notice mistake)

instead of
public void reduce(Text key, Iterable<IntWritable> values, Reducer.Context
context) throws IOException, InterruptedException
be should
public void reduce(Text key, Iterable<IntWritable> values, Reducer<Text,
IntWritable, Text, IntWritable>.Context context) throws IOException,
InterruptedException

The complete working sample looks like
package org.prototype4u.mapreduce;

import java.io.IOException;
import java.util.StringTokenizer;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

public class WordCount {

public static class WordCountMapper extends Mapper<LongWritable, Text, Text,
IntWritable> {

@Override
protected void map(LongWritable key, Text value, Context context) throws
IOException, InterruptedException {
StringTokenizer st = new StringTokenizer(value.toString());
while (st.hasMoreTokens()) {
context.write(new Text(st.nextToken()), new IntWritable(1));
}
}
}

public static class WordCountReduce extends Reducer<Text, IntWritable, Text,
IntWritable> {

@Override
public void reduce(Text key, Iterable<IntWritable> values, Reducer<Text,
IntWritable, Text, IntWritable>.Context context) throws IOException,
InterruptedException {
int sum = 0;
for (IntWritable value : values) {
sum += value.get();
}
context.write(key, new IntWritable(sum));
}

}

public static void main(String[] args) throws IOException,
InterruptedException, ClassNotFoundException {
Job job = new Job();
job.setJobName("WordCounter");
job.setJarByClass(WordCount.class);
job.setMapperClass(WordCountMapper.class);
job.setReducerClass(WordCountReduce.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true)? 0 :1);
}
}

Thank you for the hint.

Regards,
Vitaliy S