public class MiltorgMapper extends Mapper<LongWritable, Text, Text, Text> {
    private static final Logger log = LoggerFactory.getLogger(MiltorgMapper.class);

    @Override
    protected void map(LongWritable key, Text val, Context context) throws IOException, InterruptedException {
        log.info("key: {} val {}", key, val);
        int [] numbers = Stream.of(val.toString().split(";"))
                .mapToInt(Integer::parseInt)
                .toArray();
        Set<Integer> integerSet = Arrays.stream(numbers).boxed().collect(Collectors.toSet());
        TreeSet<Integer> tSetNumbers = new TreeSet<Integer>( integerSet);

        List<Set<Integer>> combinations = generateCombinations(tSetNumbers, 9);
        for (Set<Integer> c: combinations) {
            context.write( new Text(c.toString()), val) ;
        }

    }

    public static List<Set<Integer>> generateCombinations(Set<Integer> from, int size) {
        Set<Set<Integer>> elements = Sets.powerSet(from);
        List<Set<Integer>> possibleCombinations = elements.stream().filter(p -> p.size() == size).collect(Collectors.toList());
        return possibleCombinations;
    }

}

public class MiltorgReducer extends Reducer<Text, Text, Text, Text> {
        private static final Logger log = LoggerFactory.getLogger(MiltorgReducer.class);

        @Override
        protected void reduce(Text key, Iterable<Text> values, Context context) throws IOException,InterruptedException  {
            Integer matches = 0;
            for (Text value :values) {
                matches++;
            }
            if (matches>2) {
                context.write(new Text(key.toString()), new Text(matches.toString()));
            }
    }

}