RecyclerviewListeners

Show how to use extension function to handle recyclerView item and subItem listeners.

There are different ways to handle recyclerView item click listener, today I am going to use kotlin extension function to handle the item click listener and different listeners for sub view in the recycleView cell.

* Using Extenstion fun

• Row (item) click listener
• SubView click listener
• CompoundButton onCheckedChanged listener Code

          //RadioButton, Checkbox, Switch
fun RecyclerView.addOnCheckedChangeListener(onCheckedChangeListener: OnCheckedChangeListener) {
    this.addOnChildAttachStateChangeListener(object : RecyclerView.OnChildAttachStateChangeListener {
        override fun onChildViewAttachedToWindow(view: View) {
            val holder = getChildViewHolder(view)
            for (index in 0 until (view as ViewGroup).childCount) {
                val subview = view.getChildAt(index)
                if(subview is CompoundButton) {
                    subview.setOnCheckedChangeListener { compoundButton, b ->
                        onCheckedChangeListener.onCheckedChanged(compoundButton, b, holder.adapterPosition)
                    }
                }
            }
        }

         override fun onChildViewDetachedFromWindow(view: View) {
            for (index in 0 until (view as ViewGroup).childCount) {
                val subview = view.getChildAt(index)
                if(subview is CompoundButton) {
                    subview.setOnCheckedChangeListener (null)
                }
            }
        }
    })

• RadioGroup onCheckedChanged listener Code

fun RecyclerView.addOnRadioGroupCheckedChangeListener(onRadioGroupCheckedChangeListener: OnRadioGroupCheckedChangeListener) {
    this.addOnChildAttachStateChangeListener(object : RecyclerView.OnChildAttachStateChangeListener {
        override fun onChildViewAttachedToWindow(view: View) {
            val holder = getChildViewHolder(view)
            for (index in 0 until (view as ViewGroup).childCount) {
                val subview = view.getChildAt(index)
                if (subview is RadioGroup) {
                    subview.setOnCheckedChangeListener { group, buttonId ->
                        onRadioGroupCheckedChangeListener.onCheckedChanged(group, buttonId, holder.adapterPosition)
                    }
                }
            }
        }

        override fun onChildViewDetachedFromWindow(view: View) {
            for (index in 0 until (view as ViewGroup).childCount) {
                val subview = view.getChildAt(index)
                if (subview is RadioGroup) {
                    subview.setOnCheckedChangeListener(null)
                }
            }
        }
    })
}

* Using inline fun Full Code

* Memory impact