Kotlin (4): Getters and Setters

Properties in Kotlin

var author: String = "Steven"

This is the same as defining the following get() and set() methods:

(example 1:)

var author: String = "Steven"

    get() {

        return field

    }

    set(value) {

        field = value

    }

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(example 2:)

class Rectangle(val width: Int, val height: Int) {

    val area: Int // property type is optional since it can be inferred from the getter's return type

        get() = this.width * this.height

}

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(example 3:)

var stringRepresentation: String

    get() = this.toString()

    set(value) {

        setDataFromString(value) 

    }

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Backing fields:

Every property we define is backed by a field that can only be accessed within its get() and set() methods using the special field keyword.

(example:)

var counter = 0 

    set(value) {

        if (value >= 0) field = value

    }

or

var rating: Int = 5 get() { if (field < 5) { print("Warning: this is a terrible book") } return field } set(value) { field = when { value > 10 -> 10 value < 0 -> 0 else -> value } }

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