Kotlin - How to correctly concatenate a String

Question

A very basic question, what is the right way to concatenate a String in Kotlin?

In Java you would use the concat() method, e.g.

String a         


        

Answer 1

In Kotlin, you can concatenate using string interpolation / templates:

val a = "Hello"
val b = "World"
val c = "$a $b"

The output will be: Hello World

Or you can concatenate using the + / plus() operator:

val a = "Hello"
val b = "World"
val c = a + b   // same as calling operator function a.plus(b)

print(c)

The output will be: HelloWorld

Or you can concatenate using the StringBuilder.

val a = "Hello"
val b = "World"

val sb = StringBuilder()
sb.append(a).append(b)
val c = sb.toString()

print(c)

The output will be: HelloWorld