Type mismatch: inferred type is BluetoothDevice? but BluetoothDevice was expected

Question

I know that this is a very simple error but I can't quite comprehend the nuances of kotlin enough to solve it just yet.

I'm getting the error:

Type mismatch: inferred type is BluetoothDevice? but BluetoothDevice was expected

When trying to pass a BluetoothDevice in as parcelable

class ScanDevice(var device: BluetoothDevice, var rssi: Int): Parcelable {
   ...
    constructor(parcel: Parcel) : this(
        parcel.readParcelable(BluetoothDevice::class.java.classLoader), <--- here
        parcel.readInt()
    )
    ...

It's technically just a warning and not actually an error but I'm not sure what is happening here.

Answer 1

The documentation for Parcel.readerParcelable() says:

Returns the newly created Parcelable, or null if a null object has been written.

This means that, if we were living in Kotlin world, the return type of Parcel.readParcelable() would be T? and not T (i.e. it would be nullable).

Since you are in control of the writing, you know that it won't return null. That means that you're safe to convert the result to a non-nullable type by using the !! operator:

parcel.readParcelable(BluetoothDevice::class.java.classLoader)!!