How to store custom objects in Dataset?

Question

According to Introducing Spark Datasets:

As we look forward to Spark 2.0, we plan some exciting improvements to Datasets, specifically: ... Custom

Answer 1

For those who may in my situation I put my answer here, too.

To be specific,

1. I was reading 'Set typed data' from SQLContext. So original data format is DataFrame.

   val sample = spark.sqlContext.sql("select 1 as a, collect_set(1) as b limit 1") sample.show()

   +---+---+ | a| b| +---+---+ | 1|[1]| +---+---+

2. Then convert it into RDD using rdd.map() with mutable.WrappedArray type.

   sample .rdd.map(r => (r.getInt(0), r.getAs[mutable.WrappedArray[Int]](1).toSet)) .collect() .foreach(println)

   Result:

   (1,Set(1))