hadoop in mapper combiner
public static class Map extends Mapper<Object, Text, Text, IntWritable> { Map count = new HashMap<Integer, Integer>(); public void map(Object key, Text value, Context context) throws IOException, InterruptedException { StringTokenizer itr = new StringTokenizer(value.toString()); while (itr.hasMoreTokens()) { String token = itr.nextToken(); int length = token.length(); if(count.containsKey(length)) { int sum = (int) count.get(length) + 1; count.put(length, sum); } else { count.put(length, 1); } } } public void cleanup(Context context) throws IOException, InterruptedException { Iterator<Map.Entry<Integer, Integer>> temp = count.entrySet().iterator(); while(temp.hasNext()) { Map.Entry<Integer, Integer> entry = temp.next(); String keyVal = entry.getKey()+""; Integer countVal = entry.getValue(); context.write(new Text(keyVal), new IntWritable(countVal)); } } }