String splitting- splitting by hashtag

Question

I'm new to Scala, so I've tried to work my way up to reading text files. I am trying to create an object with a method that takes in a string representing a filename and returns an int which is the sum of the values. However, the text file is annoyingly separated by hashtags.

This is what the sample text file looks like:

3#1#8
12#9#25#10
-2#12
1#2


How do you split this?

`Source.fromFile(fileName).getLines().flatMap(_.split("#")).flatMap(_.toIntOption).sum` — Luis Miguel Mejía Suárez, Jan 02 '20 at 22:24
That code is all you need. It should work on **Scala 2.13**. If you are on **2.12** or older `toIntOption` does not exists but can be easily replaced with `map(_toInt)` if you are sure all values are numbers or with `flatMap(str => Try(str.toInt).toOption)`. — Luis Miguel Mejía Suárez, Jan 02 '20 at 22:28
`split()` returns an `Array`. Many have already asked about why an `Array` won't pretty print and how to fix it. — jwvh, Jan 02 '20 at 22:59
My bad, I see now. So just to clarify, are you supposed to use .mkstring(" ") in general to print arrays because they won't pretty print? — indentation, Jan 02 '20 at 23:02
`.mkString()` is a popular fix. Others like `.toList` or `.toSeq`. And there are a few more esoteric solutions. — jwvh, Jan 02 '20 at 23:12

score 1 · Answer 1 · answered Jan 02 '20 at 22:25

split is a Java method that returns Java Array which are not pretty-printed in Scala by default, instead they are printed as hashcodes. To pretty print it try

import scala.runtime.ScalaRunTime.stringOf
println(stringOf("3#1#8".split("#")))

which outputs

Array(3, 1, 8)

score 1 · Accepted Answer · answered Jan 02 '20 at 22:25

1

That's correct. Look:

scala> "A#B#C".split("#").toString // (*)
res2: String = [Ljava.lang.String;@24f3e13e

You can do this:

scala> "A#B#C".split("#").toList
res3: List[String] = List(A, B, C)

(*) New REPL is not calling toString from java.lang.Array, and show a more pleasant output, so I added it explicitly to illustrate the issue.

answered Jan 02 '20 at 22:25

pedrofurla

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Oh, ok, I didn't know that was even a problem. So every time I want to check what's going on, I'm gonna need to do that? – indentation Jan 02 '20 at 22:33

String splitting- splitting by hashtag

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