Filterable & Searchable Recyclerview.

RecyclerActivity.kt

       searchView.setOnQueryTextListener(object : SearchView.OnQueryTextListener {
            override fun onQueryTextChange(newText: String): Boolean {
                adapter.filter.filter(newText)
                return false
            }

            override fun onQueryTextSubmit(query: String): Boolean {
                return false
            }
        })

RecyclerAdapter.kt

class SubActivityListAdapter : RecyclerView.Adapter<SubActivityListAdapter.ActivityHolder>(), Filterable {

var mOriginalArrayList: ArrayList<YourItem> = ArrayList()
    var mFilteredList: ArrayList<YourItem> = ArrayList()

    fun addList(items: ArrayList<YourItem>) {
        this.mOriginalArrayList = items
        this.mFilteredList = items
        notifyDataSetChanged()
    }

    private fun addFilteredList(items: ArrayList<YourItem>) {
        mFilteredList = items
        notifyDataSetChanged()
    }
  
      private val mFiler: Filter = object : Filter() {
        override fun performFiltering(constraint: CharSequence): FilterResults {
            val filteredList: ArrayList<YourItem?> = ArrayList()

            if (constraint.isEmpty()) {
                filteredList.addAll(mOriginalArrayList)
            } else {
                val filterPattern = constraint.toString().toLowerCase().trim { it <= ' ' }
                for (item in mOriginalArrayList) {
                    if (item.name?.toLowerCase()!!.contains(filterPattern)) {
                        filteredList.add(item)
                    }
                }
            }
            val results = FilterResults()
            results.values = filteredList
            return results
        }

        override fun publishResults(constraint: CharSequence, results: FilterResults) {
            addFilteredList(results.values as ArrayList<YourItem>)
        }
    }

    override fun getFilter(): Filter = mFiler

}