The way I understood things is that the word "variable" referred to the capability of a reference to be reassigned. "constant" meant a reference cannot be reassigned. Essentially the difference between final or not in Java.
var something = new obj() -> reference can be re-assigned
val something = new obj() -> cannot be re-assigned
To me "mutability" meant the ability to modify the REFERAND/OBJECT itself, not its reference. I.E. the object being referenced. But Kotlin doesn't prevent that.
You can have
val something = new obj()
but still be able to "mutate" that obj() without reassigning to a new identifier.
Am I misunderstanding something, or is this a misnomer?
CodePudding user response:
val
and var
only control the immutability of the reference not the object that it points to.
From Kotlin in Action
There are two keywords to declare a variable:
val
(from value)—Immutable reference. A variable declared withval
can’t be reassigned after it’s initialized. It corresponds to afinal
variable in Java.var
(from variable)—Mutable reference. The value of such a variable can be changed. This declaration corresponds to a regular (non-final) Java variable.Note that, even though a
val
reference is itself immutable and can’t be changed, the object that it points to may be mutable. For example, this code is perfectly valid:
val languages = arrayListOf("Java") languages.add("Kotlin")