java - Kotlin 术语 "mutable"错了吗？

Question

我理解事物的方式是“变量”一词指的是重新分配引用的能力。 “常量”意味着不能重新分配引用。本质上是 Java 中 final 与 not 的区别。

var something = new obj() -> reference can be re-assigned  
val something = new obj() -> cannot be re-assigned

对我来说，“可变性”意味着修改 REFERAND/OBJECT 本身的能力，而不是它的引用。 IE。 被引用的对象。但 Kotlin 并没有阻止这一点。

你可以拥有

val something = new obj()

但仍然能够“变异”该 obj() 而无需重新分配给新标识符。

是我误解了什么，还是用词不当？

Answer 1

val和 var只控制引用的不变性，而不是它指向的对象。

来自 Kotlin in Action

There are two keywords to declare a variable:

1. val (from value)—Immutable reference. A variable declared with val can’t be reassigned after it’s initialized. It corresponds to a final variable in Java.
2. 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")