相当于 RecyclerView 中 ViewHolder 的 onAttachedToWindow()/onDetachedFromWindow()

Question

I'm converting a bunch of Views to use the ViewHolder pattern in RecyclerView instead. I have code that needs to be run in onAttachedToWindow() and onDetachedFromWindow(), or whatever's closest to it in terms of the View lifecycle. What can I do to replicate that?

Answer 1

We can implement View.OnAttachStateChangeListener in our ViewHolder :

class SomeViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView),
View.OnAttachStateChangeListener {

    ...

    init {
         itemView.addOnAttachStateChangeListener(this)
    }

    override fun onViewDetachedFromWindow(v: View?) {
        // Do what you need
    }

    override fun onViewAttachedToWindow(v: View?) {
        // Do what you need
    }
}

In Adapter we set view in onCreateViewHolder(...) :

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): SomeViewHolder {
    val view = LayoutInflater.from(parent.context).inflate(R.layout.some_item, parent, false)
    return SomeViewHolder(view)
}