What methods can be used to concatenate strings in Kotlin?

In Kotlin, strings can be concatenated in several ways:

1. Using the + operator:

val result = "Hello, " + "world!"

2. String interpolation (string templates):

val name = "John"
val greeting = "Hello, $name!"

3. Using the plus() method:

val result = "Hello, ".plus("world!")

4. Using StringBuilder for efficient concatenation of many strings:

val builder = StringBuilder()
builder.append("Hello, ")
builder.append("world!")
val result = builder.toString()

5. Using the joinToString() function to concatenate collections of strings:

val words = listOf("Hello", "world")
val result = words.joinToString(separator = ", ")

The choice of method depends on the task and performance considerations.