Var str:String is mutable or immutable?

Language Design
1

Hi,

Is var str:String mutable or immutable?

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As per document var is mutable…

But.

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And String is immutable…

Please clarify contradiction.

2

Val states that the reference is immutable, the value can not be reasigned:

val a : String = "hi" 
a = "b"  //not valid because a is reassigned

The variable which is referenced can change, depending on its implementation:

val a = mutableListOf<String>() //can change
val  b = listOf<String>()  //cannot change

The implementation of String is that it can’t change, so String itself is immutable.

3

And to be quite precise val does not mean immutable, it means read-only. See Redirect Notice