如何在foreach循环中运行sc.textFile（）并对其进行并集？

Question

so this is what I have been trying and I'm a newbie here working with spark!

I'm trying to execute this code

val ii=sc.parallelize(Seq(("e.txt"),("r.txt"))).foreach{i => sc.textFile(i)}

but I'm getting "Nullpointer exception"

Thanks!

Answer 1

You can just add multiple files to the sc.textFile . You should not use the sc inside of a map operation. The map function will be distributed to the different executors, and the sc lives in the driver. Therefore it will throw a Nullpointer exception.

a.txt contents:

a.txt:line1
a.txt:line2

b.txt contents:

b.txt:line1
b.txt:line2

Spark allows you to add more files in the same operation:

scala> sc.textFile("a.txt,b.txt").collect()
res1: Array[String] = Array(a.txt:line1, a.txt:line2, b.txt:line1, b.txt:line2)

Hope this helps and have fun with Spark!