Using “m” prefix for variables in Kotlin

Question

Using \"m\" prefix for variable names became usual in programming, mainly in Android, but since Kotlin arrived, this minor thing bothers me a bit.

Setting and getting va

Answer 1

I actually don’t think it’s good practise to have prefixed variables in the public API, thus foo.mName = "Foo" would be undesirable. For private fields this would be acceptable though.

The official conventions for the Kotlin language say:

Names for backing properties

If a class has two properties which are conceptually the same but one is part of a public API and another is an implementation detail, use an underscore as the prefix for the name of the private property:

class C {
    private val _elementList = mutableListOf<Element>()

    val elementList: List<Element>
         get() = _elementList
}

Answer 2

Per the Android Kotlin Style Guide:

Special prefixes or suffixes, like those seen in the examples name_, mName, s_name, and kName, are not used except in the case of backing properties (see “Backing properties”).

Therefore you should not use the "m" prefix for variables in Kotlin.

Answer 3

A good reference from Android

https://android.github.io/kotlin-guides/style.html

Special prefixes or suffixes, like those seen in the examples name_, mName, s_name, and kName, are not used except in the case of backing properties (see “Backing properties”).