I have a RecyclerView
and my Fragment
. I am getting data from Firebase Realtime Database
into a RecyclerView.
I need to make it so that while the data is loading, I see some kind of loading effect. How can i do this?
Code from my Fragment:
private var _binding: FragmentDayDetailBinding? = null
private val binding get() = _binding!!
private var ref: DatabaseReference? = null
private lateinit var adapter: DayDetailAdapter
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentDayDetailBinding.inflate(inflater, container, false)
setupRecyclerView()
initDatabase()
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
readFromDatabase()
}
private fun setupRecyclerView() {
adapter = DayDetailAdapter()
binding.recyclerView.layoutManager = LinearLayoutManager(requireContext())
binding.recyclerView.adapter = adapter
}
private fun initDatabase() {
FirebaseApp.initializeApp(requireContext())
ref = FirebaseDatabase.getInstance()
.getReference("IMIT")
.child("groups")
}
private fun readFromDatabase() {
ref?.addValueEventListener(object: ValueEventListener {
override fun onDataChange(snapshot: DataSnapshot) {
if (snapshot.exists()) {
val list = ArrayList<Day>()
for (daySnapshot in snapshot.children) {
val day = daySnapshot.getValue(Day::class.java)
list.add(day!!)
}
adapter.submitList(list)
} else {
binding.apply {
lrDbEmpty.visibility = View.VISIBLE
recyclerView.visibility = View.INVISIBLE
}
}
}
override fun onCancelled(error: DatabaseError) {
}
})
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
Code from RecyclerView Adapter:
class ViewHolder(private val binding: ItemSubjectDetailBinding): RecyclerView.ViewHolder(binding.root) {
fun bind(day: Day) = with(binding) {
tvSubject.text = day.subject
tvInfo.text = "${day.teacher}, ${day.type}"
tvTime.text = day.time
tvAud.text = day.classroom
}
companion object {
fun from(parent: ViewGroup): ViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
val binding = ItemSubjectDetailBinding.inflate(layoutInflater, parent, false)
return ViewHolder(binding)
}
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder.from(parent)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
with(holder) {
bind(getItem(position))
}
}
class ItemComparator: DiffUtil.ItemCallback<Day>() {
override fun areItemsTheSame(oldItem: Day, newItem: Day): Boolean {
return oldItem == newItem
}
override fun areContentsTheSame(oldItem: Day, newItem: Day): Boolean {
return oldItem == newItem
}
}
CodePudding user response:
You already in half the way
Create a progressBar in the center of the fragment
<ProgressBar
android:id="@ id/progress_bar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
Keep it visible until the data fetched (onDataChange
Called) then hide the progressBar
override fun onDataChange(snapshot: DataSnapshot) {
binding.progressBar.visibility = View.GONE
if (snapshot.exists()) {
// rest of your code
}
}