Détecter quand RecyclerView atteint la position la plus basse en faisant défiler
j'ai ce code pour RecyclerView.
recyclerView = (RecyclerView)rootview.findViewById(R.id.fabric_recyclerView);
recyclerView.setLayoutManager(layoutManager);
recyclerView.addItemDecoration(new RV_Item_Spacing(5));
FabricAdapter fabricAdapter=new FabricAdapter(ViewAdsCollection.getFabricAdsDetailsAsArray());
recyclerView.setAdapter(fabricAdapter);
j'ai besoin de savoir quand le RecyclerView atteint la position la plus basse pendant le scrolling. Est-il possible ? Si oui, comment ?
7 réponses
il y a aussi une façon simple de le faire
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
if (!recyclerView.canScrollVertically(1)) {
Toast.makeText(YourActivity.this, "Last", Toast.LENGTH_LONG).show();
}
}
});
entiers de direction: -1 pour up, 1 pour down, 0 retournera toujours false.
il suffit d'implémenter un addonscrollllistener() sur votre recyclerview. Puis à l'intérieur de l'écouteur scroll mettre en œuvre le code ci-dessous.
RecyclerView.OnScrollListener mScrollListener = new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
if (mIsLoading)
return;
int visibleItemCount = mLayoutManager.getChildCount();
int totalItemCount = mLayoutManager.getItemCount();
int pastVisibleItems = mLayoutManager.findFirstVisibleItemPosition();
if (pastVisibleItems + visibleItemCount >= totalItemCount) {
//End of list
}
}
};
Il y a ma place, il est très utile pour StaggeredGridLayout
.
Utilisation :
private EndlessScrollListener scrollListener =
new EndlessScrollListener(new EndlessScrollListener.RefreshList() {
@Override public void onRefresh(int pageNumber) {
//end of the list
}
});
rvMain.addOnScrollListener(scrollListener);
mise en œuvre de L'écoute :
class EndlessScrollListener extends RecyclerView.OnScrollListener {
private boolean isLoading;
private boolean hasMorePages;
private int pageNumber = 0;
private RefreshList refreshList;
private boolean isRefreshing;
private int pastVisibleItems;
EndlessScrollListener(RefreshList refreshList) {
this.isLoading = false;
this.hasMorePages = true;
this.refreshList = refreshList;
}
@Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
StaggeredGridLayoutManager manager =
(StaggeredGridLayoutManager) recyclerView.getLayoutManager();
int visibleItemCount = manager.getChildCount();
int totalItemCount = manager.getItemCount();
int[] firstVisibleItems = manager.findFirstVisibleItemPositions(null);
if (firstVisibleItems != null && firstVisibleItems.length > 0) {
pastVisibleItems = firstVisibleItems[0];
}
if (visibleItemCount + pastVisibleItems >= totalItemCount && !isLoading) {
isLoading = true;
if (hasMorePages && !isRefreshing) {
isRefreshing = true;
new Handler().postDelayed(new Runnable() {
@Override public void run() {
refreshList.onRefresh(pageNumber);
}
}, 200);
}
} else {
isLoading = false;
}
}
public void noMorePages() {
this.hasMorePages = false;
}
void notifyMorePages() {
isRefreshing = false;
pageNumber = pageNumber + 1;
}
interface RefreshList {
void onRefresh(int pageNumber);
} }
la réponse est en Kotlin, ça marchera en Java. L'ide doit convertir il pour vous si vous copiez et collez.
recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener(){
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
// 3 lines below are not needed.
Log.d("TAG","Last visible item is: ${gridLayoutManager.findLastVisibleItemPosition()}")
Log.d("TAG","Item count is: ${gridLayoutManager.itemCount}")
Log.d("TAG","end? : ${gridLayoutManager.findLastVisibleItemPosition() == gridLayoutManager.itemCount-1}")
if(gridLayoutManager.findLastVisibleItemPosition() == gridLayoutManager.itemCount-1){
// We have reached the end of the recycler view.
}
super.onScrolled(recyclerView, dx, dy)
}
})
Cela fonctionnera aussi pour les LinearLayoutManager
parce qu'il a les mêmes méthodes utilisées ci-dessus. findLastVisibleItemPosition()
et getItemCount()
(itemCount
à Kotlin).
Essayez Ceci
j'ai utilisé les réponses ci-dessus, il s'exécute toujours lorsque vous allez à la fin de recycleur de vue,
Si vous voulez vérifier une seule fois si c'est sur un fond ou pas? Exemple: - si j'ai la liste des 10 articles chaque fois que je vais en bas, il m'affichera et à nouveau si je fais défiler haut en bas, il ne sera pas imprimer à nouveau, et si vous ajoutez plus de listes et vous allez là-bas, il s'affichera à nouveau.
Remarque: utilisez cette méthode lorsque vous traitez avec décalage frapper API
créer une classe nommée Endlessrecyclerviewscrollistener
import android.support.v7.widget.GridLayoutManager; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.support.v7.widget.StaggeredGridLayoutManager; public abstract class EndlessRecyclerViewScrollListener extends RecyclerView.OnScrollListener { // The minimum amount of items to have below your current scroll position // before loading more. private int visibleThreshold = 5; // The current offset index of data you have loaded private int currentPage = 0; // The total number of items in the dataset after the last load private int previousTotalItemCount = 0; // True if we are still waiting for the last set of data to load. private boolean loading = true; // Sets the starting page index private int startingPageIndex = 0; RecyclerView.LayoutManager mLayoutManager; public EndlessRecyclerViewScrollListener(LinearLayoutManager layoutManager) { this.mLayoutManager = layoutManager; } // public EndlessRecyclerViewScrollListener() { // this.mLayoutManager = layoutManager; // visibleThreshold = visibleThreshold * layoutManager.getSpanCount(); // } public EndlessRecyclerViewScrollListener(StaggeredGridLayoutManager layoutManager) { this.mLayoutManager = layoutManager; visibleThreshold = visibleThreshold * layoutManager.getSpanCount(); } public int getLastVisibleItem(int[] lastVisibleItemPositions) { int maxSize = 0; for (int i = 0; i < lastVisibleItemPositions.length; i++) { if (i == 0) { maxSize = lastVisibleItemPositions[i]; } else if (lastVisibleItemPositions[i] > maxSize) { maxSize = lastVisibleItemPositions[i]; } } return maxSize; } // This happens many times a second during a scroll, so be wary of the code you place here. // We are given a few useful parameters to help us work out if we need to load some more data, // but first we check if we are waiting for the previous load to finish. @Override public void onScrolled(RecyclerView view, int dx, int dy) { int lastVisibleItemPosition = 0; int totalItemCount = mLayoutManager.getItemCount(); if (mLayoutManager instanceof StaggeredGridLayoutManager) { int[] lastVisibleItemPositions = ((StaggeredGridLayoutManager) mLayoutManager).findLastVisibleItemPositions(null); // get maximum element within the list lastVisibleItemPosition = getLastVisibleItem(lastVisibleItemPositions); } else if (mLayoutManager instanceof GridLayoutManager) { lastVisibleItemPosition = ((GridLayoutManager) mLayoutManager).findLastVisibleItemPosition(); } else if (mLayoutManager instanceof LinearLayoutManager) { lastVisibleItemPosition = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition(); } // If the total item count is zero and the previous isn't, assume the // list is invalidated and should be reset back to initial state if (totalItemCount < previousTotalItemCount) { this.currentPage = this.startingPageIndex; this.previousTotalItemCount = totalItemCount; if (totalItemCount == 0) { this.loading = true; } } // If it’s still loading, we check to see if the dataset count has // changed, if so we conclude it has finished loading and update the current page // number and total item count. if (loading && (totalItemCount > previousTotalItemCount)) { loading = false; previousTotalItemCount = totalItemCount; } // If it isn’t currently loading, we check to see if we have breached // the visibleThreshold and need to reload more data. // If we do need to reload some more data, we execute onLoadMore to fetch the data. // threshold should reflect how many total columns there are too if (!loading && (lastVisibleItemPosition + visibleThreshold) > totalItemCount) { currentPage++; onLoadMore(currentPage, totalItemCount, view); loading = true; } } // Call this method whenever performing new searches public void resetState() { this.currentPage = this.startingPageIndex; this.previousTotalItemCount = 0; this.loading = true; } // Defines the process for actually loading more data based on page public abstract void onLoadMore(int page, int totalItemsCount, RecyclerView view); }
utilisez cette classe comme ceci
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity()); recyclerView.setLayoutManager(linearLayoutManager); recyclerView.addOnScrollListener(new EndlessRecyclerViewScrollListener( linearLayoutManager) { @Override public void onLoadMore(int page, int totalItemsCount, RecyclerView view) { Toast.makeText(getActivity(),"LAst",Toast.LENGTH_LONG).show(); } });
Son fonctionnement parfait sur ma fin, commnent moi si vous obtenez toute question
j'étais aussi à la recherche de cette question mais je n'ai pas trouvé la réponse qui me satisfait, donc je crée sa propre réalisation de recyclerView.
ma solution résoudre ce problème.
class CustomRecyclerView: RecyclerView{
abstract class TopAndBottomListener{
open fun onBottomNow(onBottomNow:Boolean){}
open fun onTopNow(onTopNow:Boolean){}
}
constructor(c:Context):this(c, null)
constructor(c:Context, attr:AttributeSet?):super(c, attr, 0)
constructor(c:Context, attr:AttributeSet?, defStyle:Int):super(c, attr, defStyle)
private var linearLayoutManager:LinearLayoutManager? = null
private var topAndBottomListener:TopAndBottomListener? = null
private var onBottomNow = false
private var onTopNow = false
private var onBottomTopScrollListener:RecyclerView.OnScrollListener? = null
fun setTopAndBottomListener(l:TopAndBottomListener?){
if (l != null){
checkLayoutManager()
onBottomTopScrollListener = createBottomAndTopScrollListener()
addOnScrollListener(onBottomTopScrollListener)
topAndBottomListener = l
} else {
removeOnScrollListener(onBottomTopScrollListener)
topAndBottomListener = null
}
}
private fun createBottomAndTopScrollListener() = object :RecyclerView.OnScrollListener(){
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
checkOnTop()
checkOnBottom()
}
}
private fun checkOnTop(){
val firstVisible = linearLayoutManager!!.findFirstCompletelyVisibleItemPosition()
if(firstVisible == 0 || firstVisible == -1 && !canScrollToTop()){
if (!onTopNow) {
onTopNow = true
topAndBottomListener?.onTopNow(true)
}
} else if (onTopNow){
onTopNow = false
topAndBottomListener?.onTopNow(false)
}
}
private fun checkOnBottom(){
var lastVisible = linearLayoutManager!!.findLastCompletelyVisibleItemPosition()
val size = linearLayoutManager!!.itemCount - 1
if(lastVisible == size || lastVisible == -1 && !canScrollToBottom()){
if (!onBottomNow){
onBottomNow = true
topAndBottomListener?.onBottomNow(true)
}
} else if(onBottomNow){
onBottomNow = false
topAndBottomListener?.onBottomNow(false)
}
}
private fun checkLayoutManager(){
if (layoutManager is LinearLayoutManager)
linearLayoutManager = layoutManager as LinearLayoutManager
else
throw Exception("for using this listener, please set LinearLayoutManager")
}
private fun canScrollToTop():Boolean = canScrollVertically(-1)
private fun canScrollToBottom():Boolean = canScrollVertically(1)
}
puis dans votre activité/fragment:
override fun onCreate() {
customRecyclerView.layoutManager = LinearLayoutManager(context)
}
override fun onResume() {
super.onResume()
customRecyclerView.setTopAndBottomListener(this)
}
override fun onStop() {
super.onStop()
customRecyclerView.setTopAndBottomListener(null)
}
j'espère qu'il va hepl quelqu'un ;-)
C'est ma solution:
val onScrollListener = object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView?, dx: Int, dy: Int) {
directionDown = dy > 0
}
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
if (recyclerView.canScrollVertically(1).not()
&& state != State.UPDATING
&& newState == RecyclerView.SCROLL_STATE_IDLE
&& directionDown) {
state = State.UPDATING
// TODO do what you want when you reach bottom, direction
// is down and flag for non-duplicate execution
}
}
}