Is there a way to initiliase an interface without creating a new class just like in java?

Support
1

like some people do

someFunctionThatRequiresInterfaceTypeAsArgument(interface()
{
    override bool getRandomBoolean()
    {
        return Random.nextBool()
    }
})

etc. is there a way to do this same thing in kotlin without creating a new class from this interface?

1 Like
2 
someFunctionThatRequiresInterfaceTypeAsArgument(object : InterfaceName
{
    override bool getRandomBoolean()
    {
        return Random.nextBool()
    }
})
1 Like
3

Sure, you can use object expression to implement the interface anonymously:

import kotlin.random.Random

fun someFunctionThatRequiresInterfaceTypeAsArgument(foo: MyInterface) = println(foo.getRandomBoolean())

//sampleStart
interface MyInterface {
    fun getRandomBoolean(): Boolean
}

fun main() {
    someFunctionThatRequiresInterfaceTypeAsArgument(object: MyInterface {
        override fun getRandomBoolean() = Random.Default.nextBoolean()
    })
}
//sampleEnd

Additionally, if your interface has exactly one method, you can define it as a fun interface and implement like that:

import kotlin.random.Random

fun someFunctionThatRequiresInterfaceTypeAsArgument(foo: MyInterface) = println(foo.getRandomBoolean())

//sampleStart
fun interface MyInterface {
    fun getRandomBoolean(): Boolean
}

fun main() {
    someFunctionThatRequiresInterfaceTypeAsArgument(MyInterface { Random.Default.nextBoolean() })
}
//sampleEnd
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