CODEWITHSUNDEEP
functionclasskotlinif-statement
ProAslan
ProAslan

Reputation: 63

Trying to use if function in Kotlin class

I don´t know why it doesn´t work.. I cant use if or when functions in class or in the "playerPosition" function..

class Player(val name:String, val nachname: String, val nr:Int) {
    var position = mutableListOf<Int>(0,1,2,3)
    var playerPosi = Int


    fun playerPosition(){

      if(playerPosi < 3 ){

      }
    }

}

And the next question is, how can I use a function from a class in the main func.? Maybe like this

class Player(val name:String, val nachname: String, val nr:Int, var playerPosi : Int) {
    var position = mutableListOf<Int>(0,1,2,3)



    fun playerPosition(){

      if(playerPosi > 3 ){
          println("Diese Position gibt es nicht")

      }
    }



   }

MAIN FUNCTION

fun main(){
    val team2 = mutableListOf<Player>()
    team2.add(Player("Berkan", "Kutlu", 10,4))
    val spieler = Player("Wesley","Sneijder",10,4)


    playerPosition()

    println("${team2.first().playerPosi}")



    }

notice Im trying to set the max Int from playerPosi to 3. Because of Offense, Middfield and Defense and Keeper If Ive the numbers from 0 to 3 I will try to identify 0 as Keeper 1 as Defense and so on.

Thanks for you patience with me :D

Upvotes: 0

Views: 263

Answers (3)

Jolan DAUMAS
Jolan DAUMAS

Reputation: 1374

First question

The problem here is not the if keyword, it's because the property playerPosi is wrong.

Instead of writing :

var playerPosi = Int

you need to write :

var playerPosi: Int

Why ?

In kotlin, you have two way to declare a variable / property :

  • var : mutable variable / property, you can change it's value
  • val : read-only variable (check Tenfour04 response)

After the var / val keyword you give it a name

And after that you have three choices :

  • Directly give a value and kotlin will infer the type
var playerPosi = 1
  • Give it a type and initialize it latter
var playerPosi: Int
  • Give it a type and initialize it
var playerPosi: Int = 1

Second Question

If you want to call a method of an object (here it's Player), you need to :

  • Instantiate it
  • Get the reference
  • Call the method from the reference

So, if we take your sample :

    val team2 = mutableListOf<Player>()
    team2.add(Player("Berkan", "Kutlu", 10,4))
    val spieler = Player("Wesley","Sneijder",10,4) // Instantiate + take the reference on spieler variable.


    speiler.playerPosition() // here you call the playerPosition method with the speiler variable

    println("${team2.first().playerPosi}")

Upvotes: 3

Gawron
Gawron

Reputation: 85

Try changing from var playerPosi = Int to var playerPosi: Int, with : instead of =. If you want to define the data type, you should use :; = is used to assign value.

To use the function on object you have previously created, you should first specify the object you want the function to be called into, then a dot, and then the function's name. Like this:

fun main(){
    val spieler = Player("Wesley","Sneijder",10,4)
    spieler.playerPosition()
}

Upvotes: 2

ivan.ukr
ivan.ukr

Reputation: 3551

In the first case: var playerPosi = Int is wrong syntax. Declaration should be var playerPosi: Int.

In the second case: if player is object of class Player, the you can do player.playerPosi.

main() function seems to be written for variant #2, where playerPosi is also constructor parameter.

Upvotes: 1

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