public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable>
  {  
    private static final IntWritable ONE = new IntWritable(1);
    private static final Text BIGRAM = new Text();
      
    public void map(Object key, Text value, Context context) throws IOException, InterruptedException
     {
       String line = value.toString();
	   String prev = null;
       StringTokenizer itr = new StringTokenizer(line);
      while (itr.hasMoreTokens()) 
      {
        String cur = itr.nextToken();
        // Emit only if we have an actual bigram.
        if (prev != null) 
        {
          BIGRAM.set(prev + " " + cur);
          context.write(BIGRAM, ONE);
        }
        prev = cur;
      } 
     }
  }