= code v0.20 = 

{{{
#!java
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.StringTokenizer;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.filecache.DistributedCache;
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.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
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.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.StringUtils;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class WordCount2for020 extends Configured implements Tool {

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

		static enum Counters {
			INPUT_WORDS
		}

		private final static IntWritable one = new IntWritable(1);
		private Text word = new Text();

		private boolean caseSensitive = true;
		private Set<String> patternsToSkip = new HashSet<String>();

		private long numRecords = 0;
		private String inputFile;

		public void setup(Context context) {
			Configuration conf = context.getConfiguration();
			caseSensitive = conf.getBoolean("wordcount.case.sensitive", true);
			inputFile = conf.get("map.input.file");

			if (conf.getBoolean("wordcount.skip.patterns", false)) {
				Path[] patternsFiles = new Path[0];
				try {
					patternsFiles = DistributedCache.getLocalCacheFiles(conf);
				} catch (IOException ioe) {
					System.err
							.println("Caught exception while getting cached files: "
									+ StringUtils.stringifyException(ioe));
				}
				for (Path patternsFile : patternsFiles) {
					parseSkipFile(patternsFile);
				}
			}
		}

		private void parseSkipFile(Path patternsFile) {
			try {
				BufferedReader fis = new BufferedReader(new FileReader(
						patternsFile.toString()));
				String pattern = null;
				while ((pattern = fis.readLine()) != null) {
					patternsToSkip.add(pattern);
				}
			} catch (IOException ioe) {
				System.err
						.println("Caught exception while parsing the cached file '"
								+ patternsFile
								+ "' : "
								+ StringUtils.stringifyException(ioe));
			}
		}

		public void map(LongWritable key, Text value,
				OutputCollector<Text, IntWritable> output, Reporter reporter)
				throws IOException {
			String line = (caseSensitive) ? value.toString() : value.toString()
					.toLowerCase();

			for (String pattern : patternsToSkip) {
				line = line.replaceAll(pattern, "");
			}

			StringTokenizer tokenizer = new StringTokenizer(line);
			while (tokenizer.hasMoreTokens()) {
				word.set(tokenizer.nextToken());
				output.collect(word, one);
				reporter.incrCounter(Counters.INPUT_WORDS, 1);
			}

			if ((++numRecords % 100) == 0) {
				reporter.setStatus("Finished processing " + numRecords
						+ " records " + "from the input file: " + inputFile);
			}
		}
	}

	public static class Reduce extends
			Reducer<Text, IntWritable, Text, IntWritable> {
		public void reduce(Text key, Iterator<IntWritable> values,
				OutputCollector<Text, IntWritable> output, Reporter reporter)
				throws IOException {
			int sum = 0;
			while (values.hasNext()) {
				sum += values.next().get();
			}
			output.collect(key, new IntWritable(sum));
		}
	}

	public int run(String[] args) throws Exception {
		Configuration conf = new Configuration();

		Job job = new Job(conf);
		job.setJarByClass(WordCount2for020.class);
		job.setJobName("wordcount");
		
		job.setMapOutputKeyClass(Text.class);
		job.setMapOutputValueClass(IntWritable.class);
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(IntWritable.class);

		job.setMapperClass(Map.class);
		job.setCombinerClass(Reduce.class);
		job.setReducerClass(Reduce.class);

		job.setInputFormatClass(TextInputFormat.class);
		job.setOutputFormatClass(TextOutputFormat.class);

		List<String> other_args = new ArrayList<String>();
		for (int i = 0; i < args.length; ++i) {
			if ("-skip".equals(args[i])) {
				DistributedCache
						.addCacheFile(new Path(args[++i]).toUri(), conf);
				conf.setBoolean("wordcount.skip.patterns", true);
			} else {
				other_args.add(args[i]);
			}
		}
//		conf.set("mapred.job.tracker", "local");
//		conf.set("fs.default.name", "file:///");

		FileInputFormat.setInputPaths(job, new Path(other_args.get(0)));
		FileOutputFormat.setOutputPath(job, new Path(other_args.get(1)));
		job.waitForCompletion(true);

		return 0;
	}

	public static void main(String[] args) throws Exception {
		String[] argv = { "-Dwordcount.case.sensitive=false",
				"/user/waue/text_input", "/user/waue/output-v020", "-skip",
				"/user/waue/patterns" };
		args = argv;
		int res = ToolRunner.run(new Configuration(), new WordCount2for020(),
				args);
		System.exit(res);
	}
}
}}}
 = error message =
{{{
10/04/19 09:57:17 INFO input.FileInputFormat: Total input paths to process : 4
10/04/19 09:57:17 INFO mapred.JobClient: Running job: job_201004190849_0004
10/04/19 09:57:18 INFO mapred.JobClient:  map 0% reduce 0%
10/04/19 09:57:28 INFO mapred.JobClient: Task Id : attempt_201004190849_0004_m_000000_0, Status : FAILED
java.io.IOException: Type mismatch in key from map: expected org.apache.hadoop.io.Text, recieved org.apache.hadoop.io.LongWritable
	at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:807)
	at org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:504)
	at org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)
	at org.apache.hadoop.mapreduce.Mapper.map(Mapper.java:124)
	at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
	at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:583)
	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:305)
	at org.apache.hadoop.mapred.Child.main(Child.java:170)
}}}