Smartcasting to and from platform type in kotlin

Question

I am using kotlin to create my adapter which extends BaseAdapter in android. below is the code inside getView method

override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View? {
        var binding : ImageBinding
        var conView = convertView
        if(conView == null){
            binding = DataBindingUtil.inflate(LayoutInflater.from(parent?.context),
                    R.layout.image, parent, false)
            conView = binding.root;
            conView.tag = binding
        }else {
            binding = conView.getTag() as ImageBinding
        }

        return conView;
}

conView.tag = binding and binding = conView.getTag() is highlighted in a pink-like color.When i hover over conView.tag = binding with my mouse, a popup appears with a message Smart cast to android.view.View!. And when i hover over binding = conView.tag,a popup appears with a message Smart cast to android.view.View. Note the difference in the two messages where the latter is missing the platform type sign (!)

How can i implement the two suggested options?

Answer 1

Because convertView is a nullable type variable(View?), var conView = convertView assigment creates a copy of a nullable conView variable. So you should handle conView variable as nullable.

Try the following way:

override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View? {
    var binding : ImageBinding
    convertView?.let {
        binding = it.tag as ImageBinding
        return it
    }
    binding = DataBindingUtil.inflate(LayoutInflater.from(parent?.context), R.layout.image, parent, false)
    val conView = binding.root
    conView.tag = binding
    return conView
}

Note: Semicolons in Kotlin are not required, be aware of that