Kotlin Academy · Lesson

companion object: Static-like Members in Kotlin

Add companion objects to classes to simulate static methods and constants.

No static, but companion object

Kotlin has no static keyword. Instead, a companion object declared inside a class provides class-level (static-like) members.

Put a companion object inside a class. Its members are callable as ClassName.member.

class MathUtils {
    companion object {
        fun square(x: Int) = x * x
    }
}
fun main() {
    println(MathUtils.square(5)) // 25
}