How to set a non-inline OnClickListener in Kotlin?

Question

I want to attach a View.OnClickListener to a Button. I don't want the OnClickListener to be an inline anonymous function definition. Rather, I want to define it outside the bounds of the onCreateView() function.

In Java, I would do this as follows:

@Override public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                       Bundle savedInstanceState)
{
    View view = inflater.inflate(R.layout.my_layout, container, false);
    View my_btn = view.findViewById(R.id.my_btn);
    my_btn.setOnClickListener(handleButtonClick);
    return view;
}

View.OnClickListener handleButtonClick = new View.OnClickListener()
{
    @Override public void onClick(View v) 
    {
        Log.d("my_tag", "click!")
    }
}

Other answers seems to suggest the following will work, but it does not compile for me:

    override fun onCreateView(name: String?, context: Context?, attrs: AttributeSet?): View
    {
        var view = super.onCreateView(name, context, attrs)
        my_btn.setOnClickListener( handleButtonClick  )
        return view
    }

    private val handleButtonClick = View.OnClickListener 
    {  
        view->
        Log.d("my_tag", "click!")
    }

What is wrong with the above, and how can I define an OnClickListener as a named property on my Activity class?

Answer 1

Indenting correctly fix the issue.

private val handleButtonClick = View.OnClickListener {  view->
    Log.d("my_tag", "click!")
}

as mentioned by others, as the view param is the single one and is ignored, you can get rid of it.

if you want using an object:

val handleButtonClick = object : View.OnClickListener {
    override fun onClick(view: View) {
        Log.d("my_tag", "click!")
    }
}

Edit : As mentioned by @Mango, this is a limitation stated in the grammar definition.

Answer 2

If you don't want lambda notations then this might work for you:

val onClickListener = object : View.OnClickListener {
    override fun onClick(view: View) {
        //ToDo: Implement whatever method you need
    }
}