var Array of objects not initialising [duplicate] - arrays

Question

This question already has an answer here:
Function returns an empty List in Spark
(1 answer)
Closed 4 years ago.
I've a following code :-
case class event(imei: String, date: String, gpsdt: String, entrygpsdt: String,lastgpsdt: String)
object recalculate extends Serializable {
def main(args: Array[String]) {
val sc = SparkContext.getOrCreate(conf)
val rdd = sc.cassandraTable("db", "table").select("imei", "date", "gpsdt").where("imei=? and date=? and gpsdt>? and gpsdt<?", entry(0), entry(1), entry(2), entry(3))
var lastgpsdt = "2018-04-06 10:10:10"
var updatedValues = new Array[event](rdd.count().toInt)
var index = 0
rdd.foreach(f => {
val imei = f.get[String]("imei")
val date = f.get[String]("date")
val gpsdt = f.get[String]("gpsdt")
updatedValues(index) = new event(imei, date, gpsdt,lastgpsdt)
println(updatedValues(index).toString())
index = index + 1
lastgpsdt = gpsdt
})
println("updates values are " + updatedValues.toString())
}}
So, here I'm trying to create an array of event class answer save values in array on each iteration and want to access the array outside foreach block. My issue is when I'm trying to access the array it gives null pointer exception and i checked it shows the array is empty. Although I have declared the array as var still why not able to access outside. Suggestions please, Thanks.

Answer 1

If you want to get Array[event] then I don't think that is the right approach
Here is what you can do for alternative
case class event(imei: String, date: String, gpsdt: String,
entrygpsdt: String,lastgpsdt: String)
val result = rdd.map(row => {
val imei = row.getString(0)
val date = row.getString(1)
val gpsdt = row.getString(2)
//create case class as you want
event(imei, date, gpsdt, lastgpsdt ,"2018-04-06 10:10:10")
})
.collect()
The result you obtain is Array[event]
Collect is also preferred only when your data size is small and can fit in a driver.
Hope this helps!