<https://kotlinlang.org/docs/object-declarations.html> 1. is `x` not data property? 2. what is d...

# getting-started

[anlex N]

https://kotlinlang.org/docs/object-declarations.html

1. is x not data property?
2. what is data property? I can not find difinition in Properties

[hfhbd]

I find the name "data property" confusing too, it’s not used anywhere else, but it stands for the properties defined in the (primary) constructor of a data class:

data class Foo(val b: Int) {
val s: String = ""
}

b is a "data property", while s is a normal property.

[anlex N]

so crazy and confused. can we invite JetBrain team to answer this question?

[CLOVIS]

There's nothing more to say, what Philip said is correct. A data property is just a property that's in the primary constructor of a data class.

[Jacob]

https://kotlinlang.org/docs/data-classes.html#properties-declared-in-the-class-body describes the significance of properties declared in constructor

[Klitos Kyriacou]

It seems to be true that the term "data properties" is not defined properly before use on that page. However, it is defined formally in the Kotlin Language Specification:

A data class is a special kind of class, which represents a product type constructed from a number of data properties, [...], described in its primary constructor.

It may be worth asking someone from JetBrains if they would make the tutorial page on data classes clearer with respect to this definition.

[gildor]

There is a literally "Edit page" button on top of the page to send PR