Constructors and init block in Kotlin

Classes.kt

// primary constructor with fullName property (setter & getter)
class Person(val fullName: String) { /*...*/ }

// define a secondary constructor
class Person(val fullName: String) {
    val age: Int
        get() {
            return 18
        }

    // secondary constructor
    constructor(fullName: String, age: Int) : this(fullName) {}
}

// instance of the class
val john = Person("John", 24)

// init block
class Person(val fullName: String) {
    var isLongName = false

    init {
        isLongName = fullName.length > 15
    }
}