How to Implement Search/Filter for RecyclerView
July 24, 2020Overview
The best way is to filter the items sent into adapter, but I can’t do this because I am using FirestoreRecyclerAdapter
.
I cannot filter via Firestore database operation because I am doing partial text search.
I perform search by by manipulating RecyclerView.Adapter.getItemCount
and RecyclerView.Adapter.getItem
.
Perform search by selectively hiding the view is not recommended, as sometimes you might end up with a blank view which still occupy the space.
Another interesting solution is via SortedList, as shown in this example.
Model
The adapter support 2 types of view
class Note {
open val name: String?
get() = doc.get("name") as? String
}
class Update(val doc: DocumentSnapshot) {
open val content: String?
get() = doc.get("content") as? String
}
Adapter
Calling search
will trigger notifyDataSetChanged
, which trigger getItemCount
and getItem
which will show the appropriate items.
private class LocalAdapter(options: FirestoreRecyclerOptions<Post>, val viewModel: HomeViewModel) : FirestoreRecyclerAdapter<Post, LocalAdapter.ViewHolder>(options) {
private var searchText: String = ""
// indicate if search mode
private val isSearch: Boolean
get() = searchText.isNotBlank()
// store the list of filtered search items
private var searchItems: MutableList<Post> = mutableListOf()
override fun getItemViewType(position: Int): Int {
return when(val item = getItem(position)) {
is Note -> R.layout.home_item_note
is Update -> R.layout.home_item_update
else -> R.layout.home_item_note
}
// return super.getItemViewType(position)
}
override fun getItemCount(): Int {
return if (isSearch) {
searchItems = mutableListOf()
for (position in 0 until super.getItemCount()) {
var item = super.getItem(position)
when(item) {
is Note -> {
// will regex be faster?
// or store lowercase text(all related fields) as map
// or use internal text search engine
if (item.name?.toLowerCase()?.contains(searchText) == true) {
searchItems.add(item)
}
}
is Update -> {
if (item.content?.toLowerCase()?.contains(searchText) == true) {
searchItems.add(item)
}
}
}
}
searchItems.size
}
else {
super.getItemCount()
}
}
override fun getItem(position: Int): Post {
return if (!isSearch) {
super.getItem(position)
}
else {
searchItems[position]
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): LocalAdapter.ViewHolder {
val view = LayoutInflater.from(parent.context)
.inflate(viewType, parent, false)
return ViewHolder(view)
}
override fun onBindViewHolder(
holder: LocalAdapter.ViewHolder,
position: Int,
item: Post
) {
// holder.batchNoTextView.text = "#${item.batchNo}"
// holder.nameTextView.text = item.name
when(item) {
is Note -> {
bindNote(holder, item)
}
is Update -> {
bindUpdate(holder, item)
}
}
}
private fun bindNote(holder: ViewHolder, item: Note) {
holder.apply {
noteNameTextView.text = item.name
}
}
private fun bindUpdate(holder: ViewHolder, item: Update) {
holder.apply {
updateContentTextView.text = item.content
}
}
fun search(text: String) {
searchText = text
notifyDataSetChanged()
}
inner class ViewHolder(override val containerView: View) : RecyclerView.ViewHolder(containerView),
LayoutContainer
}
SearchView
Refer to Add SearchView To Android Toolbar to capture search input.
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