How to check "instanceof " class in kotlin?

user_2949612 0
Viewed 138348

In kotlin class, I have method parameter as object (See kotlin doc here ) for class type T. As object I am passing different classes when I am calling method. In Java we can able to compare class using instanceof of object which class it is.

So I want to check and compare at runtime which Class it is?

How can I check instanceof class in kotlin?

kotlin-extension kotlin
8 Answers

Combining when and is:

when (x) {
    is Int -> print(x + 1)
    is String -> print(x.length + 1)
    is IntArray -> print(x.sum())
}

copied from official documentation

user_56525130

You can check like this

 private var mActivity : Activity? = null

then

 override fun onAttach(context: Context?) {
    super.onAttach(context)

    if (context is MainActivity){
        mActivity = context
    }

}
user_54166150

You can read Kotlin Documentation here https://kotlinlang.org/docs/reference/typecasts.html . We can check whether an object conforms to a given type at runtime by using the is operator or its negated form !is, for the example using is: 

fun <T> getResult(args: T): Int {
    if (args is String){ //check if argumen is String
        return args.toString().length
    }else if (args is Int){ //check if argumen is int
        return args.hashCode().times(5)
    }
    return 0
}

then in main function i try to print and show it on terminal :

fun main() {
    val stringResult = getResult("Kotlin")
    val intResult = getResult(100)

    // TODO 2
    println(stringResult)
    println(intResult)
}

This is the output

6
500
user_102644260

Other solution : KOTLIN

val fragment = supportFragmentManager.findFragmentById(R.id.fragment_container)

if (fragment?.tag == "MyFragment")
{}
user_58692170
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