WordCount version one

package org.myorg;

import java.io.IOException; import java.util.StringTokenizer; import org.apache.hadoop.conf.Configured; 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.input.FileSplit; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import org.apache.log4j.Logger;

public class WordCount extends Configured implements Tool { private static final Logger LOG = Logger.getLogger(WordCount.class); public static void main(String[] args) throws Exception { int res = ToolRunner.run(new WordCount(), args); System.exit(res); }

public int run(String[] args) throws Exception { Job job = Job.getInstance(getConf(), "wordcount"); job.setJarByClass(this.getClass()); // Use TextInputFormat by default, or use job.setInputFormatClass FileInputFormat.addInputPath(job, new Path(args[0])); FileOutputFormat.setOutputPath(job, new Path(args[1])); job.setMapperClass(Map.class); job.setReducerClass(Reduce.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); return job.waitForCompletion(true) ? 0 : 1; }

public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> { private final static IntWritable one = new IntWritable(1); private Text word = new Text(); private long numRecords = 0;

`public void map(LongWritable offset, Text lineText, Context context)`
    `throws IOException, InterruptedException {`
  `String line = lineText.toString();`
  `StringTokenizer tokenizer = new StringTokenizer(line);`
  `while (tokenizer.hasMoreTokens()) {`
    `word.set(tokenizer.nextToken());`
    `context.write(word, one);`
    `context.getCounter(Counters.INPUT_WORDS).increment(1);`
  `}`
`}`
`private enum Counters {INPUT_WORDS}`

} public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> { @Override public void reduce(Text word, Iterable<IntWritable> counts, Context context) throws IOException, InterruptedException { int sum = 0; for (IntWritable count : counts) { sum += count.get(); } context.write(word, new IntWritable(sum)); } } }