Search dari recycleview caranya gimana ya. kotlin firebase

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_recycle_motor)
        supportActionBar!!.title = "List Motor"
        supportActionBar!!.setDisplayHomeAsUpEnabled(true)

        fetchmotor()
        searchmotor.setHint("Search.....")
        searchmotor.addTextChangeListener(object : TextWatcher {
            override fun afterTextChanged(p0: Editable?) {

            }

            override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {

            }

            override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
                val searchtext = searchmotor.text.toString().toUpperCase()

            }

        })
    }

    private fun fetchmotor() {

        val ref = FirebaseDatabase.getInstance().getReference("/Motor")
        ref.addListenerForSingleValueEvent(object: ValueEventListener {
            override fun onDataChange(p0: DataSnapshot) {
                val listrecycle = GroupAdapter<ViewHolder>()
                p0.children.forEach {
                    val motor = it.getValue(motor::class.java)
                    if (motor != null) {
                        listrecycle.add(motorItem(motor))
                    }
                }

                MotorRecycleview.adapter = listrecycle

            }

            override fun onCancelled(p0: DatabaseError) {
                TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
            }
        })

    }
}

class motorItem(val motor: motor): Item<ViewHolder>() {
    override fun bind(viewHolder: ViewHolder, position: Int) {
    viewHolder.itemView.Mnopol.text = motor.nopolisi
        viewHolder.itemView.Mnama.text = motor.nama
    }

    override fun getLayout(): Int {
        return R.layout.designmotor
    }
}