Examples with Double org.apache.kafka.common.serialization.Serdes.Double used on opensource projects

Example 1 with Double

use of org.apache.kafka.common.serialization.Serdes.Double in project kafka-tutorials by confluentinc.

the class RunningAverage method getRatingAverageTable.

protected static KTable<Long, Double> getRatingAverageTable(KStream<Long, Rating> ratings, String avgRatingsTopicName, SpecificAvroSerde<CountAndSum> countAndSumSerde) {
    // Grouping Ratings
    KGroupedStream<Long, Double> ratingsById = ratings.map((key, rating) -> new KeyValue<>(rating.getMovieId(), rating.getRating())).groupByKey(with(Long(), Double()));
    final KTable<Long, CountAndSum> ratingCountAndSum = ratingsById.aggregate(() -> new CountAndSum(0L, 0.0), (key, value, aggregate) -> {
        aggregate.setCount(aggregate.getCount() + 1);
        aggregate.setSum(aggregate.getSum() + value);
        return aggregate;
    }, Materialized.with(Long(), countAndSumSerde));
    final KTable<Long, Double> ratingAverage = ratingCountAndSum.mapValues(value -> value.getSum() / value.getCount(), Materialized.as("average-ratings"));
    // persist the result in topic
    ratingAverage.toStream().to(avgRatingsTopicName);
    return ratingAverage;
}