String

Learn the String type and its methods.

String

A String is a sequence of zero or more characters. It is written between double quotes: "Hello". In Kotlin, strings are immutable; once created, their content does not change.

Common operations: length, uppercase(), substring(b, e).

val s = "Kotlin"
println(s.length)      // 6
println(s.uppercase()) // KOTLIN

Exercise String operations

Write a fun main(). Declare val name = "kotlin". Print with println(name.length) and println(name.uppercase()).

Show example solution

fun main() {
    val name = "kotlin"
    println(name.length)
    println(name.uppercase())
}

String concatenation

You can concatenate two strings with +: "Hello " + "Kotlin" → "Hello Kotlin". But a more readable approach is a string template: "Hello $name".

Templates are shorter than concatenation and convert the variable's type to a string automatically. Numeric values can also be embedded directly as $n.

Test yourself

What does `"Kotlin".length` return?
- 5
- 7
- It throws an error
- 6
Show answer

6 — "Kotlin" has 6 characters.
String: match the terms

length

Length
uppercase()

Uppercase
substring()

Substring
lowercase()

Lowercase

String: fill in the missing part

val s = "kotlin"
println(s.____())

Show answer

val s = "kotlin"
println(s.uppercase())

Next lesson: Any and Unit

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