Search code examples
kotlingetter-settergetter

Kotlin explicit vs implicit get() and set()

What are the reason why we use or explicitly use get() and set() in Kotlin? I have a model that is throwing an error when I remove explicit get() in its variable declaration.

data class SampleDomain(
    val publishTime: String = ""
) {

    // Removing get() here, publishTime becomes empty
    val formattedDate: String
        get() = LocalDate.parse(publishTime, DateTimeFormatter.ISO_OFFSET_DATE_TIME).format(
            DateTimeFormatter.ofPattern("MMM. dd, yyyy")
        )

}
Solution

  • get() and set() is how we define getters and setters in Kotlin. So simply answering why do we use them is because they are required to define a getter/setter.

    If you mean the difference between the following definitions:

    val formattedDate: String = acquireDate()
val formattedDate: String get() = acquireDate()

    Then get() is not here just to be more explicit. These two code fragments do much different things. The first acquires the date during the object initialization, stores it inside a field and the getter returns this stored value. The second defines a custom getter, but the value is not stored anywhere - the date is acquired again and again every time the getter is invoked.

    See the documentation for more info: https://kotlinlang.org/docs/properties.html#getters-and-setters