Kotlin How to call method that passed as parameter

Question

in javasript, if we know the name of the method, we can pass it as parameter and call it like this

function foo(methodName){
	methodName()
}

function doSomething(){
	console.log("DO Something")
}
foo(doSomething)

I want to do something like this in kotlin, consider i have a class like this

Class DataModel{}
Class Foo (){
    fun build(data:DataModel,val onThis:AnyMethod){
        if(data.size>0){
            val param = somevalue
            onThis(param)
        }
    }
}

then in my Activity for example i have doThis method

class MainActivity : AppCompatActivity(){
    //rest of code
    fun doThis(param:Int){
        Log.e("DO","THIS ${param}")
    }
}

in my OnCreateView i want to call something like this

val a= new Foo()
a.build(data, doThis)

To do this, how my Foo Class should be?

Enselic · Accepted Answer · 2019-09-30 07:51:31Z

4

Change val onThis:AnyMethod to onThis: (Int) -> Unit, i.e. like this:

class Foo {
    fun build(data: DataModel, onThis: (Int) -> Unit) {
        if (data.size > 0) {
            val param = somevalue
            onThis(param)
        }
    }
}

Then you can do like this

// val mainActivity: MainActivity = ...

val a = Foo()
a.build(data, mainActivity::doThis)

or, if you run that code from within a member function of MainActivity:

val a = Foo()
a.build(data, ::doThis)

More information on how to pass around lambdas/functions/member functions can be found in the official documentation.

edited Sep 30, 2019 at 7:51

answered Sep 30, 2019 at 4:55

Enselic

5,0222 gold badges32 silver badges43 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Matius Nugroho Aryanto Over a year ago

I have edited my question since i found new problem, what if the function needs parameter?

Enselic Over a year ago

@MatiusNugrohoAryanto Then you change from () -> Unit to (Int) -> Unit.

Collectives™ on Stack Overflow

Kotlin How to call method that passed as parameter

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related