Part 24 – Init Blocks


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In part 24 of the Kotlin beginner tutorial, we will learn how to declare init blocks that execute code whenever an object is created from a class, and where we can validate constructor arguments before assigning them to a classes’ properties.

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KotlinTutorial.kt
fun main() {
    val user1 = User("   Hans   ", 30)
    val user2 = User("  Elfriede   ", 60)
    val user3 = User(age = 60)
    val user4 = User("    ", 20)
}

class User(name: String = "No Name", var age: Int) {
    init {
        print("New user created. Age: $age,")
    }

    val name: String

    init {
        if (name.isBlank()) {
            this.name = "No Name"
        } else {
            this.name = name.trim()
        }

        println(" Name: ${this.name}")
    }
}