Kotlin - Sort MutableList based on Object Property

Question

I have this Token Object:

class Token(type: TokenType, value: String, position: IntRange = 0..0)

I declare a MutableList:

val tokens: MutableList<Token> = mutableListOf()

// Mutable List filled

Now I want to sort my list based on the first value of the position IntRange. I tried doing this:

tokens
          .sortedBy { it.position.first }

However, I have no access to the object after using the it keyword, so position is highlighted red.

Any suggestions?

Answer 1

Another observation is that sortedBy returns a sorted copy of the list. If you want to sort your mutable list in place, you should use sortBy function:

tokens.sortBy { it.position.first } 
// tokens is sorted now

Answer 2

try with sortBy method,

val result = tokens.sortBy { it.position } 

Answer 3

The position is a parameter rather than a property, to make it to a property on the primary constructor by val/var keyword, for example:

//makes the parameter to a property by `val` keyword---v
class Token(val type: TokenType,  val value: String,  val position:IntRange = 0..0)

THEN you can sort your Tokens by the position, for example:

tokens.sortedBy { it.position.first }