Driver.java

package com.inferdata.hadoop;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;


public class Driver {

	public static void main(String[] args) throws Exception { 
	    Configuration cnf = new Configuration();


		cnf.set("delims", " \t\r\n.,()[]{}+-*/=;:");
		Job conf = new Job(cnf, "word count");
	    conf.setJarByClass(Driver.class);
	    conf.setOutputKeyClass(Text.class);
		conf.setOutputValueClass(LongWritable.class);
		
	    FileInputFormat.addInputPath(conf, new Path("input"));
	    FileOutputFormat.setOutputPath(conf, new Path("output"));

		conf.setMapperClass(WordCountMapper.class);
		conf.setReducerClass(SumReducer.class);
		


		try {
		    System.exit(conf.waitForCompletion(true) ? 0 : 1);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

SumReducer.java

package com.inferdata.hadoop;

import java.io.IOException;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.io.Text;



public class SumReducer extends Reducer<Text, LongWritable, Text, LongWritable> {

	public void reduce(Text key, Iterable<LongWritable> values, 
            Context context
    ) throws IOException, InterruptedException {
		
	    LongWritable result = new LongWritable();
		long sum = 0;
	      for (LongWritable val : values) {
			sum += val.get();
		}

		// output sum
	      result.set(sum);
	      context.write(key, result);
	}

}

WordCountMapper.java

package com.inferdata.hadoop;

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

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.mapreduce.Mapper;

public  class WordCountMapper extends Mapper<Object, Text, Text, LongWritable>{
	
	String delims;
	
	protected void setup(Mapper<Object, Text, Text, LongWritable>.Context context) {
		Configuration cnf = context.getConfiguration();
		delims = cnf.get("delims");
//		System.out.println("delims are: " + delims);
	}


	public void map(Object key, Text value,
			Context context) throws IOException, InterruptedException
	{
		String text = value.toString();
		StringTokenizer tokenizer = new StringTokenizer(text, delims);
//		StringTokenizer tokenizer = new StringTokenizer(text, " \t\r\n.,()[]{}+-*/=;:");
		Text word = new Text ();
		LongWritable one = new LongWritable(1);
		while (tokenizer.hasMoreTokens()) {
			word.set(tokenizer.nextToken());
			context.write(word, one);
		}

	}

}