Wie endloses Scrollen mit StaggeredLayoutManager implementieren

Question

Ich habe bereits versucht, das endlose Scrollen für LinearLayoutManager zu implementieren, und es ist erfolgreich und versucht, die LinearLayoutManager-Implementierung nach StaggeredGridLayoutManager zu kopieren, aber es funktioniert nicht.

Ich möchte nur das erste VisibleItem erhalten.

in LinearLayoutManager:

int firstVisibleItem = linearLayoutManager.findFirstVisibleItemPosition(int); 

aber in StaggeredGridLayoutManager ist:

int firstVisibleItem = staggeredGridLayoutManager.findFirstVisibleItemPositions(int[]) 

Wie die firstVisibleItem erhalten mit (int) nicht (int [])?

Gibt es eine gute Herangehensweise/Implementierung?

Vielen Dank im Voraus.

Answer 1

int mSpanCount = 2; 

int[] into = new int[mSpanCount]; 

int firstVisibleItem = staggeredGridLayoutManager.findFirstVisibleItemPositions(into)[0]; 

Answer 2

Ich habe es funktioniert:

Sie können in der StaggeredGridLayoutManager eine von zwei Methoden:

1. findFirstVisibleItemPositions(int[])
2. findFirstCompletelyVisibleItemPositions(int[])

Pass einen leeren int-Array, wird mit den Positionen initialisiert und verwendet der, der für dich Sinn macht.

private boolean loading = true; 
private int pastVisibleItems, visibleItemCount, totalItemCount; 

mRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener({ 
     @Override 
     public void onScrolled(RecyclerView recyclerView, int dx, int dy) { 

     visibleItemCount = mLayoutManager.getChildCount(); 
     totalItemCount = mLayoutManager.getItemCount(); 
     int[] firstVisibleItems = null; 
     firstVisibleItems = mLayoutManager.findFirstVisibleItemPositions(firstVisibleItems); 
     if(firstVisibleItems != null && firstVisibleItems.length > 0) { 
      pastVisibleItems = firstVisibleItems[0]; 
     } 

     if (loading) { 
      if ((visibleItemCount + pastVisibleItems) >= totalItemCount) { 
       loading = false; 
       Log.d("tag", "LOAD NEXT ITEM"); 
      } 
     } 
    } 
}); 

Answer 3

zu implementieren EndlessRecyclerOnScrollListener ersten EndlessRecyclerOnScrollListener Java-Klasse

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 EndlessRecyclerOnScrollListener extends RecyclerView.OnScrollListener { 
    public static String TAG = EndlessRecyclerOnScrollListener.class.getSimpleName(); 
    private int scrolledDistance = 0; 
    private boolean controlsVisible = false; 

    private boolean loading = true; // True if we are still waiting for the last set of data to load. 
    private int visibleThreshold = 5; // The minimum amount of items to have below your current scroll position before loading more. 

    private int pastVisibleItems, visibleItemCount, totalItemCount; 

    private int current_page = 1; 

    private StaggeredGridLayoutManager mStaggeredGridLayoutManager; 

    public EndlessRecyclerOnScrollListener(StaggeredGridLayoutManager staggeredGridLayoutManager) { 
     this.mStaggeredGridLayoutManager = staggeredGridLayoutManager; 

    } 

    @Override 
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) { 
     super.onScrolled(recyclerView, dx, dy); 

     visibleItemCount = recyclerView.getChildCount(); 
     totalItemCount = mStaggeredGridLayoutManager.getItemCount(); 
     //firstVisibleItem = mStaggeredGridLayoutManager.findFirstVisibleItemPosition(); 
     int[] firstVisibleItems = null; 
     firstVisibleItems = mStaggeredGridLayoutManager.findFirstVisibleItemPositions(firstVisibleItems); 
     if (firstVisibleItems != null && firstVisibleItems.length > 0) { 
      pastVisibleItems = firstVisibleItems[0]; 
     } 


     if (loading) { 
      if ((visibleItemCount + pastVisibleItems) >= totalItemCount) { 
       loading = false; 
       previousTotal = totalItemCount; 
      } 
     } 
     if (!loading && (totalItemCount - visibleItemCount) 
       <= (pastVisibleItems + visibleThreshold)) { 
      // End has been reached 

      // Do something 
      current_page++; 

      onLoadMore(current_page); 

      loading = true; 
     } 

     if (scrolledDistance > 1 && controlsVisible) { 
      controlsVisible = false; 
      scrolledDistance = 0; 
     } else if (scrolledDistance < -1 && !controlsVisible) { 
      controlsVisible = true; 
      scrolledDistance = 0; 
     } 

     if ((controlsVisible && dy > 0) || (!controlsVisible && dy < 0)) { 
      scrolledDistance += dy; 
     } 
    } 

    public abstract void onLoadMore(int current_page); 

    ; 
} 

Nachdem in Ihre Aktivität oder ein Fragment (in diesem Beispiel des Fragment) verwenden, um den nächsten Code

RecyclerView mRecyclerView; 
StaggeredGridLayoutManager mStaggeredGridLayoutManager; 

private RecyclerView.Adapter adapter; 

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle saveInstanceState) { 

     View v = inflater.inflate(R.layout.notices_layout, container, false); 

     mRecyclerView = (RecyclerView) v.findViewById(R.id.listaNoticias); 
mStaggeredGridLayoutManager = new StaggeredGridLayoutManager(
       2, //number of grid columns 
       GridLayoutManager.VERTICAL); 

//Sets the gap handling strategy for StaggeredGridLayoutManager 
     mStaggeredGridLayoutManager.setGapStrategy(StaggeredGridLayoutManager.GAP_HANDLING_NONE); 

     mRecyclerView.setLayoutManager(mStaggeredGridLayoutManager); 

//initializing our adapter 
adapter = new MyAdapter(list, getContext()); 

//Adding adapter to recyclerview 
mRecyclerView.setAdapter(adapter); 

mRecyclerView.setOnScrollListener(new EndlessRecyclerOnScrollListener(mStaggeredGridLayoutManager) { 
      @Override 
      public void onLoadMore(int current_page) { 
       // do something... 
       getData(current_page); 
      } 
     }); 

return v; 
} 

Answer 4

Es ist meine Implementierung erstellen , sehr nützlich für mich

Verwendung :

private EndlessScrollListener scrollListener = 
     new EndlessScrollListener(new EndlessScrollListener.RefreshList() { 
      @Override public void onRefresh(int pageNumber) { 
       //Here you can execute server connection or anything else to update data and present with Recycler view 
       // Notice: It is sync method 

      } 
     }); 

recyclerView.addOnScrollListener(scrollListener); 

Hier benutzerdefinierte Listener-Klasse:

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; 
} 

public void notifyMorePages() { 
    isRefreshing = false; 
    pageNumber = pageNumber + 1; 
} 

interface RefreshList { 
    void onRefresh(int pageNumber); 
} 
}