CODEWITHSUNDEEP
androidkotlin
ouromoros
ouromoros

Reputation: 23

Kotlin casting between classes fails

I'm learning to code in Android with Kotlin, and have issues when casting between classes.

So I had these classes defined:

abstract class ListFragment : Fragment()
class NewListFragment : ListFragment()

and when I tried to use it when implementing a function that returns a Fragment, it throws ClassCastException. There was IDE warning about the failing cast too

override fun getItem(position: Int): Fragment {
    return when(position){
        0 -> NewListFragment() as Fragment

I don't know where I got wrong

Upvotes: 0

Views: 132

Answers (1)

Salem
Salem

Reputation: 14887

Are you using the same Fragment class?

You seem to be casting to android.support.v4.app.Fragment, judging from the exception message. Are your imports in that file incorrect?

The warning in IntelliJ about an impossible cast only appears when it is truly impossible to cast to that specific type (that is, when their type hierarchies are completely different), which is why I think that this is likely the problem.

Additionally, you don't need to cast to a supertype. Such a conversion is already inferred, so you can remove the cast.

Upvotes: 4

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