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How can I display firebase data in a fragment with recyclerview? Kotlin Android Studio

hello I have an activity that has a navigation bar and fragments inside, in one of my fragments I save data in firebase, I want to get those data and display it in other fragment with recycler view. I watched a tutorial on youtube to do it cuz my teacher didn't teach us anything, the issue is the fragment that was supposed the display the data shows nothing, it's blank but I didn't understand why cuz I'm really new to this, if someone can take a look at my code and help me I would really appreciate it
This is my data class
data class Event(var eventName: String, var eventTime:String?=null)
This is ViewModel
class EventViewModel :ViewModel() {
private val repository : EventRepository
private val _allEvents = MutableLiveData<List<Event>>()
val allEvents : LiveData<List<Event>> = _allEvents
init {
repository= EventRepository().getInstance()
repository.loadEvents(_allEvents)
}
}
This is Repository
class EventRepository {
private val databaseReference: DatabaseReference= FirebaseDatabase.getInstance().getReference("PetEvents")
#Volatile private var INSTANCE : EventRepository ?=null
fun getInstance() : EventRepository{
return INSTANCE ?: synchronized(this) {
val instance = EventRepository()
INSTANCE=instance
instance
}
}
fun loadEvents(eventList : MutableLiveData<List<Event>>){
databaseReference.addValueEventListener(object:ValueEventListener{
override fun onDataChange(snapshot: DataSnapshot) {
try {
val _eventList : List<Event> = snapshot.children.map { dataSnapshot ->
dataSnapshot.getValue(Event::class.java)!!
}
eventList.postValue(_eventList)
}
catch (e: Exception){
}
}
override fun onCancelled(error: DatabaseError) {
TODO("Not yet implemented")
}
})
}
}
This is Adapter
class EventAdapter : RecyclerView.Adapter<EventAdapter.MyViewHolder>() {
private var eventList =ArrayList<Event>()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(
R.layout.event_item_cell,
parent, false
)
return MyViewHolder(itemView)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val currentItem = eventList[position]
holder.eventName.text =currentItem.eventName
holder.eventTime.text =currentItem.eventTime
}
override fun getItemCount(): Int {
return eventList.size
}
fun updateEventList(eventList: List<Event>){
this.eventList.clear()
this.eventList.addAll(eventList)
notifyDataSetChanged()
}
class MyViewHolder(itemView: View): RecyclerView.ViewHolder(itemView){
val eventName :TextView = itemView.findViewById(R.id.txEventName)
val eventTime :TextView = itemView.findViewById(R.id.txEventTime)
}
}
And this is the fragment I wish to display the data
private lateinit var viewModel : EventViewModel
private lateinit var eventRecyclerView: RecyclerView
lateinit var adapter: EventAdapter
class MainFragment : Fragment() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_main, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
eventRecyclerView=view.findViewById(R.id.recyclerView)
eventRecyclerView.layoutManager= LinearLayoutManager(context)
eventRecyclerView.setHasFixedSize(true)
adapter = EventAdapter()
eventRecyclerView.adapter= adapter
viewModel = ViewModelProvider(this).get(EventViewModel::class.java)
viewModel.allEvents.observe(viewLifecycleOwner, Observer {
adapter.updateEventList(it)
})
}
}
In my fragment xml I put a recycler view, there's no issue about that
And my item cell is a cardview idk if it has anything to with the problem I'm getting tho

RecyclerView swipe functionality breaks after orientation change

I created a RecyclerView that refreshes its list based on a database call. Each row has an options menu that is revealed when the user swipes. My original issue was that after an orientation change, the swipe gestures no longer revealed the menu. I hit all my expected breakpoints with onCreateViewHolder() and the onSwipe(). However, the row remained as the HIDE_MENU view type after swiping.
So I tried to introduce LiveData to persist the state of the list after orientation changes. The RecyclerView was still created and populated with items but now the swipe gesture crashes the application with an error:
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
Do I need to use LiveData to fix the original issue of preserving my swipe functionality after orientation changes? If not, please can someone explain why the item view types are no longer updated after orientation changes.
If I do need to use a ViewModel, what am I doing that is causing the list adapter not to receive the updated list?
HistoryFragment
class HistoryFragment : Fragment() {
private val historyViewModel by activityViewModels<HistoryViewModel>()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val root = inflater.inflate(R.layout.fragment_history, container, false)
historyViewModel.getHistoryList().observe(viewLifecycleOwner, {
refreshRecyclerView(it)
})
return root
}
private fun updateHistoryList() {
val dbHandler = MySQLLiteDBHandler(requireContext(), null)
val historyList = dbHandler.getHistoryList() as MutableList<HistoryObject>
historyViewModel.setHistoryList(historyList)
}
private fun refreshRecyclerView(historyList: MutableList<HistoryObject>) {
val historyListAdapter = HistoryListAdapter(historyList)
val callback = HistorySwipeHelper(historyListAdapter)
val helper = ItemTouchHelper(callback)
history_list.adapter = historyListAdapter
helper.attachToRecyclerView(history_list)
}
private fun setupSort() {
val sortSpinner: Spinner = history_list_controls_sort
sortSpinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
override fun onNothingSelected(parent: AdapterView<*>?) {}
override fun onItemSelected(
parent: AdapterView<*>?,
view: View?,
position: Int,
id: Long
) {
updateHistoryList()
}
}
}
override fun onViewCreated(
view: View,
savedInstanceState: Bundle?
) {
setupSort()
}
}
HistoryListAdapter
const val SHOW_MENU = 1
const val HIDE_MENU = 2
class HistoryListAdapter(private var historyData: MutableList<HistoryObject>) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
return if (viewType == SHOW_MENU) {
val inflatedView = LayoutInflater.from(parent.context).inflate(R.layout.history_list_view_row_items_menu, parent, false)
MenuViewHolder(inflatedView)
} else {
val inflatedView = LayoutInflater.from(parent.context).inflate(R.layout.history_list_view_row_items_description, parent, false)
HistoryItemViewHolder(inflatedView)
}
}
override fun getItemViewType(position: Int): Int {
return if (historyData[position].showMenu) {
SHOW_MENU
} else {
HIDE_MENU
}
}
override fun getItemCount(): Int {
return historyData.count()
}
fun showMenu(position: Int) {
historyData.forEachIndexed { idx, it ->
if (it.showMenu) {
it.showMenu = false
notifyItemChanged(idx)
}
}
historyData[position].showMenu = true
notifyItemChanged(position)
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
val item: HistoryObject = historyData[position]
if (holder is HistoryItemViewHolder) {
holder.bindItem(item)
...
}
if (holder is MenuViewHolder) {
holder.bindItem(item)
...
}
}
class HistoryItemViewHolder(v: View, private val clickHandler: (item: HistoryObject) -> Unit) : RecyclerView.ViewHolder(v) {
private var view: View = v
private var item: HistoryObject? = null
fun bindItem(item: HistoryObject) {
this.item = item
...
}
}
class MenuViewHolder(v: View, private val deleteHandler: (item: HistoryObject) -> Unit) : RecyclerView.ViewHolder(v) {
private var view: View = v
private var item: HistoryObject? = null
fun bindItem(item: HistoryObject) {
this.item = item
...
}
}
}
HistorySwipeHelper
class HistorySwipeHelper(private val adapter: HistoryListAdapter) : ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT) {
override fun onMove(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder, target: RecyclerView.ViewHolder): Boolean { return false }
override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
adapter.showMenu(viewHolder.adapterPosition)
}
override fun getSwipeThreshold(viewHolder: RecyclerView.ViewHolder): Float {
return 0.1f
}
}
HistoryViewModel
class HistoryViewModel(private var historyListHandle: SavedStateHandle) : ViewModel() {
fun getHistoryList(): LiveData<MutableList<HistoryObject>> {
return historyListHandle.getLiveData(HISTORY_LIST_KEY)
}
fun setHistoryList(newHistoryList: MutableList<HistoryObject>) {
historyListHandle.set(HISTORY_LIST_KEY, newHistoryList)
}
companion object {
const val HISTORY_LIST_KEY = "MY_HISTORY_LIST"
}
}
Activity
class MainActivity : AppCompatActivity() {
private val historyViewModel: HistoryViewModel by lazy {
ViewModelProvider(this).get(HistoryViewModel::class.java)
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
historyViewModel.setHistoryList(mutableListOf())
}
}
Thanks in advance. If this question is too broad I can try again and decompose it.

You shouldn't create new adapter every time you get an update of your history list. Keep using the same adapter, just update the items and call notifyDataSetChanged() to update the state (of course you can use different methods to notify about the insertion/deletion/etc, but make it work with notifyDataSetChanged() first).
I'm pretty sure this will fix the issue.

Passing adapter text to fragment creating problems

I want to pass data to fragment so when items in recycler adapter clicked it pass item name (sample[position].text1) fetched from firebase to fragment. I tried bundle, interface but getting error in both methods.I searched on internet but not find anything which solve my problem. mainActivity(splash screen) is only Activity in my App rest are fragments.
I used inner class method, I'm getting result but in another fragment where this adapter attached and I don't want it there.
Problem: pass sample[position].text1 to fragment so I can pass it to db.collection("here") to fetch data from Firebase.
Adapter
class dashboard_gridlayout_adapter(
private val sampledata: ArrayList<daxhboard_gridlayout_data>
): Adapter<dashboard_gridlayout_adapter.dashboard_viewholder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): dashboard_viewholder {
val itemView = LayoutInflater.from(parent.context).inflate(R.layout.dashboard_gridlayout_single_item_design, parent, false)
return dashboard_viewholder(itemView)
}
override fun onBindViewHolder(holder: dashboard_viewholder, position: Int) {
Glide.with(holder.itemView).load(sampledata[position].imageResource)
.placeholder(R.drawable.ic_baseline_history_icon)
.into(holder.imageView)
holder.textView.text = sampledata[position].text1
holder.itemView.setOnClickListener {
val appCompatActivity = it.context as AppCompatActivity
appCompatActivity.supportFragmentManager.beginTransaction()
.replace(R.id.Activity_frag_container, service_providers_list())
.addToBackStack(null)
.commit()
}
}
override fun getItemCount() = sampledata.size
inner class dashboard_viewholder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val imageView: ImageView = itemView.dashboard_adapter_image
val textView: TextView = itemView.dashboard_adapter_text
}
}
Fragment
class service_providers_list : Fragment(){
private var db = FirebaseFirestore.getInstance()
private lateinit var service_list_recycler: RecyclerView
var servlist = ArrayList<service_provider_list_data>()
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.service_providers_list, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
getserviceproviderdata()
service_list_recycler = service_provider_recycle_view.findViewById(R.id.service_provider_recycle_view)
service_provider_recycle_view.layoutManager = LinearLayoutManager(this.requireContext())
service_provider_recycle_view.setHasFixedSize(true)
}
private fun getserviceproviderdata() {
db.collection("Barber").orderBy("dist")
.get()
.addOnSuccessListener { documents ->
servlist.clear()
for (document in documents) {
val imgurl = document.data["imageResource"].toString()
val prov_name = document.data["provider_name"].toString()
val prov_address = document.data["provider_address"].toString()
val prov_rate = document.data["provider_rating"].toString()
val prov_dist = document.data["provider_distance"].toString()
servlist.add(service_provider_list_data(imgurl, prov_name, prov_address, prov_rate, prov_dist))
service_provider_recycle_view.adapter = service_provider_list_adapter(servlist)
}
}
.addOnFailureListener { exception ->
Log.e("serf", "Error getting documents: ", exception)
}
}
}
MainActivity (It's a splash screen)
class MainActivity : AppCompatActivity(){
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
#Suppress("DEPRECATION")
Handler().postDelayed(
{
supportFragmentManager.beginTransaction().replace(R.id.Activity_frag_container,Login_Screen()).commit()
},
1500
)
}
}

I solved this problem
just add new parameter(need to pass) inside replace in adapter
holder.itemView.setOnClickListener {
val datashares = sampledata[position].text1
val appCompatActivity = it.context as AppCompatActivity
appCompatActivity.supportFragmentManager.beginTransaction()
.replace(R.id.Activity_frag_container, service_providers_list(datashares))
.addToBackStack(null)
.commit()
}
and inside fragment just add
class service_providers_list(datashares: String) Fragment(){
//variable declaration
private var datasharae = datashares
(inside function where i wnt to add code i.e getserviceproviderdata() )
fun getserviceproviderdata() {
db.collection(datasharae)
.............
..............
......rest code.....
.........}

android - How to pass listener to an Adapter from a Fragment? (Kotlin)

Im currently working on an app which has a Settings Activity. In this Settings Activity there is a FrameLayout which loads a fragment containing a RecyclerView.
In the fragment, i have to pass to the RecyclerView adapter a listener, which is needed for the OnItemClick function.
I tried using context instead of this, but it doesnt work.
How do you correctly pass a listener to an Adapter?
Code:
FragmentSettings.kt
class FragmentSettingsMain : Fragment(), AdapterSettings.OnItemClickListener {
val settingsList = listOf(
DataItemsSettings(getString(R.string.look), getString(R.string.lookdescription), R.drawable.ic_colored_color_lens),
DataItemsSettings(getString(R.string.playing), getString(R.string.playingdescription), R.drawable.ic_colored_view_carousel),
DataItemsSettings(getString(R.string.images), getString(R.string.imagesdscription), R.drawable.ic_colored_image),
DataItemsSettings(getString(R.string.audio), getString(R.string.audiodescription), R.drawable.ic_colored_volume_up),
DataItemsSettings(getString(R.string.other), getString(R.string.otherdescription), R.drawable.ic_colored_shape),
DataItemsSettings(getString(R.string.about), getString(R.string.aboutdescription), R.drawable.ic_colored_info)
)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
retainInstance = true
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? = inflater.inflate(R.layout.fragment_settings_main, container, false)
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
rvSettings.apply {
layoutManager = LinearLayoutManager(activity)
adapter = AdapterSettings(settingsList, NEEDS LISTENER HERE)
}
}
override fun OnItemClick(position: Int) {
when(position) {
0 -> //Start new fragment here
1 -> //Start new fragment here
2 -> //Start new fragment here
3 -> //Start new fragment here
4 -> //Start new fragment here
5 -> this.startActivity(Intent(this, ActivityAbout::class.java))
}
}
}
AdapterSettings.kt
class AdapterSettings(
var settingsList: List<DataItemsSettings>,
var listener: OnItemClickListener
) : RecyclerView.Adapter<AdapterSettings.SettingsViewHolder>() {
inner class SettingsViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView), View.OnClickListener {
init {
itemView.setOnClickListener(this)
}
override fun onClick(p0: View?) {
val position : Int = adapterPosition
if (position != RecyclerView.NO_POSITION) {
listener.OnItemClick(position)
}
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): SettingsViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.item_settings, parent, false)
return SettingsViewHolder(view)
}
override fun getItemCount(): Int {
return settingsList.size
}
override fun onBindViewHolder(holder: SettingsViewHolder, position: Int) {
holder.itemView.apply {
rvTitle.text = settingsList[position].stringTitle
rvDescription.text = settingsList[position].stringDescription
rvIcon.setImageResource(settingsList[position].itemIcon)
}
}
interface OnItemClickListener {
fun OnItemClick(position: Int)
}
}

As you are in apply block to use this you need to add #FragmentSettingsMain while using this.
AdapterSettings(settingsList,this#FragmentSettingsMain)
Or You can use
val listener = this
rvSettings.apply{
AdapterSettings(settingsList,listener)
}

You can pass lambda to the adapter, call adapter.onAction = {}

How to Read Data from RecyclerView and send in BottomSheet

I am using recyclerView to show list of apps installed in device
image - Link
and for more details I use bottomSheet on LongPress i.e. in ViewHolder Class, but How to send data of selected tab to bottomSheet with more details(such as package name, API level etc.)...for reference see images
I want - Link
I get from below coding - Link
MainActivity.kt
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
recyclerView.adapter = Adapter // I set adapter here with function getApps()
recyclerView.layoutManager = LinearLayoutManager(this)
private fun getApps(): List<DataClass> {
// here I get apps icon,name,size and return list<DataClass>
return list
}
Adapter.kt
class Adapter(private val listOfApps: List<AppData>) :
RecyclerView.Adapter<Adapter.ViewHolder>() {
class ViewHolder(appView: View) : RecyclerView.ViewHolder(appView), View.OnClickListener,
View.OnLongClickListener {
init {
appView.setOnClickListener(this)
appView.setOnLongClickListener(this)
}
val icon: ImageView = appView.App_icon
val name: TextView = appView.App_name
val size: TextView = appView.App_size
override fun onClick(v: View?) {
Toast.makeText(v?.context, "OnClick", Toast.LENGTH_SHORT).show()
}
override fun onLongClick(v: View?): Boolean {
// I want here on Long press BottomSheet appears with details
val bottomSheetDialog = BottomSheetDialog()
// Show bottomSheet on LongPress
bottomSheetDialog.show(
(v?.context as FragmentActivity).supportFragmentManager, bottomSheetDialog.tag
)
return true
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val view = LayoutInflater.from(parent.context).inflate(
R.layout.list_apps, parent, false
)
return ViewHolder(view)
}
override fun getItemCount() = listOfApps.size
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val currentItem = listOfApps[position]
holder.icon.setImageDrawable(currentItem.icon)
holder.name.text = currentItem.name
holder.size.text = currentItem.size
}
}
BottomSheetDialog.kt
class BottomSheetDialog: BottomSheetDialogFragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.bottom_sheet, container, false)
}
override fun getTheme(): Int = R.style.RoundBottomSheetDialog
}
DataClass
data class AppData(
val icon: Drawable,
val name: String,
val size: String,
)

With your current code the easiest solution would be:
Modify your BottomSheetDialog to include AppData in the constructor
class BottomSheetDialog(val appData: AppData): BottomSheetDialogFragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.bottom_sheet, container, false)
}
override fun getTheme(): Int = R.style.RoundBottomSheetDialog
}
Add onBind method inside your ViewHolder class:
fun onBind(appData: AppData) {
icon.setImageDrawable(currentItem.icon)
name.text = currentItem.name
size.text = currentItem.size
}
Modify your onBindViewHolder method inside the Adapter to call that onBind method:
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.onBind(listOfApps[position])
}
Inside your ViewHolder add lateinit var currentItem: AppData that will be set inside onBind and we can use it in onLongClick:
class ViewHolder(appView: View) : RecyclerView.ViewHolder(appView), View.OnClickListener,
View.OnLongClickListener {
.
.
.
override fun onLongClick(v: View?): Boolean {
// I want here on Long press BottomSheet appears with details
**val bottomSheetDialog = BottomSheetDialog(currentItem)**
// Show bottomSheet on LongPress
bottomSheetDialog.show(
(v?.context as FragmentActivity).supportFragmentManager, bottomSheetDialog.tag
)
return true
}
**private lateinit var currentItem: AppData**
fun onBind(appData: AppData) {
**currentItem = appData**
icon.setImageDrawable(currentItem.icon)
name.text = currentItem.name
size.text = currentItem.size
}

attach your currentItem list item to ViewHolder inside onBindViewHolder and inside onLongClick pass this data to freshly created BottomSheetDialog, which is extending Fragment (so you may use Bundle - setArgument method). then inside onCreateView set your data to Views

Create an interface
interface OnListItemClicked {
fun onClicked(data : AppData)
}
Implement that interface in BottomSheetDialog
class BottomSheetDialog: BottomSheetDialogFragment(), OnListItemClicked {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.bottom_sheet, container, false)
}
override fun onClicked(data: AppData) {
//show Details here
}
override fun getTheme(): Int = R.style.RoundBottomSheetDialog
}
Pass extra callback to the adapter from main activity.
Adapter(private val listOfApps: List<AppData>, val onClick: (AppData) -> Unit)
Invoke the click listener from adapter with listOfAppData[position]
On MainActivity pass a function into the Adapter initialisation.
fun passDataToBottomSheet(data: AppData) {
val listener = OnListItemClicked()
listener.onClicked(data)
}
Adapter(list, ::passDataToBottomSheet)
That's it. It should work now.