By using delegating properties first example is the same as the second example without using delegates ```class User private val map MutableMap lt String String gt val name String by map val lastName String by map class User1 private val map MutableMap lt String String gt 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

The second example should be more along the lines of this ```class User private val map MutableMap lt String String gt val name String get = map name val lastName String get = map lastName ```

By using delegating properties first example is the same as kotlinlang #getting-started

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Title

Ive Vasiljevic

12/06/2019, 8:54 AM

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?

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

12/06/2019, 10:41 AM

Yes it is calling

getValue

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.

☝️ 3

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

12/06/2019, 11:43 AM

Also it doesn't just call

toString()

to fix nullability, it actually calls

getValue()

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