CODEWITHSUNDEEP
androidkotlininterfacecasting
Dylon Jaynes
Dylon Jaynes

Reputation: 176

What happens when you cast an activity to an interface in Kotlin?

I have the following interface:

interface ResultReceiver {
    fun getSerialNumber(): String
    fun getDevicePassword(): String
    fun getMacAddress(): String
    fun getDevice(): BluetoothDevice
}

Within my DialogFragment I am casting the attached Activity to my interface like so:

resultReceiver = requireActivity() as ResultReceiver

What happens when I perform this type cast?

Here is my activity code to give a little more context to my question:

class ScannerActivity: AppCompatActivity(), ResultReceiver {

    ...

    override fun getSerialNumber(): String {
        return serialNumber
    }

    override fun getDevicePassword(): String {
        return devicePassword
    }

    override fun getMacAddress(): String {
        return macAddress
    }

    override fun getDevice(): BluetoothDevice {
        return device
    }
}

I am trying to send some Strings to my fragment from my activity.

Upvotes: 1

Views: 585

Answers (1)

Hayk Mkrtchyan
Hayk Mkrtchyan

Reputation: 3255

All the activities are classes which by the end extend from Object. In Kotlin it's Any but after compilation it will be Object again. So you can take any class and try to cast it to your interface. If that class will not have any relation (parent-child) with that interface, it will throw ClassCastException.

Upvotes: 2

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