Kotlin Koans—Part 6

Insert Values into String

Kotlin upgrades some of Java’s String capabilities. One of the first things I liked was the ability to insert variables into the String

val a = 1
val b = 2
str = "Here is a String with values a=$a and b=$b)

We could of course have done this with String.format in Java

int a = 1;
int b = 2;
String str = "Here is a String with values a=%d and b=%d".format(a, b);

I think most people agree that the Kotlin approach is more concise.

Multiline Strings

Kotlin supports the “”” for mutliline strings without any need to escape charaters.

str = """
Here is a multiline String
C:\folder\file.txt

"""

The Kotlin Koans tutorial suggested that this was also useful for Regex expressions.

Task

The task for this portion of the tutorial was simple enough. We have a variable named month that we insert into a regex expression.

val month = "(JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)"

fun task5(): String{
    return """\d{2}\ $month \d{4}"""
}

This a use case for the triple quote Strings. In Java, we would have needed to escape all of the backslashes in the regex expression. I know that I am not the first developer who has gotten burned by typing \ when I should have typed \\, so the triple quote String is a nice feature.

You can click here to see Part 5.