Scala: Convert a csv string to Array

Question

I tried to convert a scala string to array by splitting it by ,.For example:

var string = "a,b,c,d,"
array =  string.split(",")
arr: Array[String] = Array(a, b, c, d)

But the output I am getting is Array(a, b, c, d), instead of Array(a, b, c, d, ). The last comma in the string is ignored by the split method. Is there any other method to solve this problem?.I presume this is trivial one, but I am new to scala. Help!

Answer 1

Use split with -1 argument.

string.split(",",-1)

To understand what the -1 argument means, let's look at the method signature

public String[] split(String regex, int limit)

The limit parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array. If the limit n is greater than zero then the pattern will be applied at most (n - 1) times, the array's length will be no greater than n, and the array's last entry will contain all input beyond the last matched delimiter.

If n is non-positive then the pattern will be applied as many times as possible and the array can have any length. If n is zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.

Examples:

scala> val myString = "a,b,c,d,,," 
scala> val stringSplit = myString.split(",")
scala> arr: Array[String] = Array(a, b, c, d)

If this time we specify the limit

scala> val myString = "a,b,c,d,,," 
scala> val stringSplitWithLimit = myString.split(",", -1)
scala> arr: Array[String] = Array(a, b, c, d, "", "", "")

This behavior comes from Java (since Scala uses Java Strings). Here is the documentation directly out of Javadoc.

Answer 2

In general case, csv is not just a list of strings with commas. For example:

 1,2,"3aa,bbb 
    cc\"c", 4
 5,6,7,8

is totally correct CSV file

So it's better to use some external parser, like this one: https://github.com/tototoshi/scala-csv