This sample app uses the below firestore recycler adapters to list the items in RecyclerView widget
-
FirestoreRecyclerAdapter
- Listens to live changes under a collection(document insert/update/delete in a collection)
- Does not support pagination
-
FirestorePagingAdapter
- Supports pagination
- Does not listen to live changes under a collection(document insert/update/delete in a collection)
Data is fetched from firestore database. Make sure you register your app in firebase and add google_services.json file inside app directory.
References
Firestore - https://firebase.google.com/docs/firestore
Firestore RecyclerView Adapter - https://github.com/firebase/FirebaseUI-Android/blob/master/firestore/README.md
Code snippets
MainActivity.kt
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
pager.adapter = PagerAdapter(2, this)
TabLayoutMediator(tabLayout, pager) { tab, position ->
tab.text = when (position) {
0 -> "Without Paging"
1 -> "With Paging"
else -> ""
}
}.attach()
}
}activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.google.android.material.tabs.TabLayout
android:id="@+id/tabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
</LinearLayout>Fruit.kt
class Fruit {
val name: String? = ""
val imgURL: String? = ""
}FruitListAdapter.kt
class FruitListAdapter(options: FirestoreRecyclerOptions<Fruit>) :
FirestoreRecyclerAdapter<Fruit, FruitItemVH>(
options
) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FruitItemVH {
val view: View = LayoutInflater.from(parent.context)
.inflate(R.layout.fruit_list_item, parent, false)
return FruitItemVH(view)
}
override fun onBindViewHolder(holder: FruitItemVH, position: Int, model: Fruit) {
holder.bindFruit(model)
}
override fun onError(e: FirebaseFirestoreException) {
Log.e("Adapter", e.message!!)
}
class FruitItemVH(itemView: View) : RecyclerView.ViewHolder(itemView) {
fun bindFruit(fruit: Fruit) {
itemView.tvName.text = fruit.name
Glide.with(itemView.context).load(fruit.imgURL).into(itemView.ivImage);
}
}
}FruitListPagingAdapter
class FruitListPagingAdapter(options: FirestorePagingOptions<Fruit>) :
FirestorePagingAdapter<Fruit, FruitListPagingAdapter.FruitItemVH>(options) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FruitItemVH {
val view: View = LayoutInflater.from(parent.context)
.inflate(R.layout.fruit_list_item, parent, false)
return FruitItemVH(view)
}
override fun onBindViewHolder(holder: FruitItemVH, position: Int, model: Fruit) {
holder.bindFruit(model)
}
class FruitItemVH(itemView: View) : RecyclerView.ViewHolder(itemView) {
fun bindFruit(fruit: Fruit) {
itemView.tvName.text = fruit.name
Glide.with(itemView.context).load(fruit.imgURL).into(itemView.ivImage);
}
}
}fruit_list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:layout_marginBottom="4dp"
app:cardBackgroundColor="@android:color/white"
app:cardCornerRadius="10dp"
app:cardElevation="5dp">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="@+id/ivImage"
android:layout_width="match_parent"
android:layout_height="150dp"
android:scaleType="centerCrop"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:src="@mipmap/ic_launcher" />
<TextView
android:id="@+id/tvName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:textSize="17sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/ivImage"
tools:text="Android" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>FirestoreRecyclerViewFragment
class FirestoreRecyclerViewFragment : Fragment() {
private lateinit var fruitsAdapter: FruitListAdapter
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_recycler_view, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val query = FirebaseFirestore.getInstance()
.collection("Fruits")
.orderBy("name")
val options = FirestoreRecyclerOptions.Builder<Fruit>()
.setQuery(query, Fruit::class.java)
.build()
fruitsAdapter = FruitListAdapter(options)
rvList.layoutManager = LinearLayoutManager(requireActivity())
rvList.adapter = fruitsAdapter
}
override fun onStart() {
super.onStart()
fruitsAdapter.startListening()
}
override fun onStop() {
super.onStop()
fruitsAdapter.stopListening()
}
companion object {
@JvmStatic
fun newInstance() = FirestoreRecyclerViewFragment()
}
}FirestoreRecyclerViewPagingFragment
class FirestoreRecyclerViewPagingFragment : Fragment() {
private lateinit var fruitsAdapter: FruitListPagingAdapter
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_recycler_view, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val query = FirebaseFirestore.getInstance()
.collection("Fruits")
.orderBy("name", Query.Direction.DESCENDING)
val config = PagedList.Config.Builder()
.setEnablePlaceholders(false)
.setPrefetchDistance(5)
.setPageSize(5) // No of items loaded from datasource
.build()
val options = FirestorePagingOptions.Builder<Fruit>()
.setQuery(query, config, Fruit::class.java)
.build()
fruitsAdapter = FruitListPagingAdapter(options)
rvList.layoutManager = LinearLayoutManager(requireActivity())
rvList.adapter = fruitsAdapter
}
override fun onStart() {
super.onStart()
fruitsAdapter.startListening()
}
override fun onStop() {
super.onStop()
fruitsAdapter.stopListening()
}
companion object {
@JvmStatic
fun newInstance() = FirestoreRecyclerViewPagingFragment()
}
}fragment_recycler_view.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="4dp"
tools:context=".ui.activities.MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/rvList"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>