Anagram.java

import java.io.IOException;
import java.util.Arrays;

import org.apache.hadoop.conf.Configuration;
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.output.FileOutputFormat;

public class Anagram {

    public static class Map extends Mapper<LongWritable, Text, Text,
            IntWritable> {
        private final static IntWritable one = new IntWritable(1);
        private Text newKey = new Text();
        public void map(LongWritable key, Text value,
                Context context)
                throws IOException, InterruptedException {
            char[] chars = value.toString().toCharArray();
            Arrays.sort(chars);
            newKey.set(new String(chars));
            context.write(newKey, one);
        }
    }

    public static class Reduce extends Reducer<Text, IntWritable, Text,
            IntWritable> {
        public void reduce(Text key, Iterable<IntWritable> values,
                Context context)
                throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable val : values) {
                sum += val.get();
            }
            if(sum >= 2) context.write(key, new IntWritable(sum));
        }
    }

  public static void main(String[] args) throws Exception {
    Configuration conf = new Configuration();
    Job job = Job.getInstance(conf, "anagram");
    job.setJarByClass(Anagram.class);
    job.setMapperClass(Map.class);
    job.setCombinerClass(Reduce.class);
    job.setReducerClass(Reduce.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(IntWritable.class);
    FileInputFormat.addInputPath(job, new Path(args[0]));
    FileOutputFormat.setOutputPath(job, new Path(args[1]));
    System.exit(job.waitForCompletion(true) ? 0 : 1);
  }
}