By using delegating properties, first example is t...

# getting-started

[Ive Vasiljevic]

By using delegating properties, first example is the same as the second example without using delegates.

class User(private val map: MutableMap<String, String>) {
    
    val name: String by map
    val lastName: String by map
}

class User1(private val map: MutableMap<String, String>) {
    
    val name: String
    val lastName: String
    
    init {
        
        name = map["name"].toString()
        lastName = map["lastName"].toString()
    }
}

So basically, when accessing property "name" from class User in the fun main(). It is using MutableMaps default getValue() implementation to get the value?

[Ive Vasiljevic]

fun main() {
   
	val user = User(mutableMapOf("name" to "Ive",
                                "lastName" to "Vasilj"))
    
    val user1 = User1(mutableMapOf("name" to "Ive",
                                "lastName" to "Vasilj"))
    
    println(user.name)
    println(user.lastName)
    
    println(user1.name)
    println(user1.lastName)
  
}

[Dominaezzz]

Yes it is calling getValue.

[Dominaezzz]

The first example and second example are not quite the same. If map is mutated, the first example will reflect the changes but the second won't. It will only have the initial values.

[Dominaezzz]

The second example should be more along the lines of this.

class User(private val map: MutableMap<String, String>) {
    val name: String get() = map["name"]
    val lastName: String get() = map["lastName"]
}

[karelpeeters]

Also it doesn't just call toString() to fix nullability, it actually calls getValue().