Disagree on two fronts : 
- By hadoop I assume you mean Map Reduce ? There are other Engines like SAMSA and FLINK and Kafka makes a great event store. Anyway, MR is super for massive throughput batch jobs, for example huge HIVE queries or Pig jobs and if you are reading, breaking the heap size, doing one thing and then writing there is no bonus from doing it in SPARK. 
- SPARK is written in Scala, which runs on the JVM. And it has a nice Java API as well !