So implementieren Sie setOnScrollListener in RecyclerView

Question

Wie zeige ich die Statusleiste unten an, wenn der Benutzer Elemente erreicht, die in einer Liste angezeigt werden.

ich einen Code geschrieben haben, in denen ich Daten immer am Web-Service, jetzt würde Ich mag teilweise Aufzeichnungen füllen, weil ich um 630 Datensätze in meinem JSON.

Hier ist mein ganzer Code, den ich verwende, um Daten von JSON zu erhalten und in RecyclerView zu füllen.

Hier ist, wie meine JSON aussieht, aber echte JSON enthält mehr als 600 Datensätze:

http://walldroidhd.com/api.php 

Kann mir jemand führen, wo ich Änderungen in meinem Code machen müssen?

Ich möchte mehr Datensätze füllen, wenn Benutzer scrollen nach unten mit Fortschrittsbalken, noch zeige ich alle Datensätze.

RecyclerViewFragment.java:

public class RecyclerViewFragment extends Fragment { 

    RecyclerView mRecyclerView; 
    LinearLayoutManager mLayoutManager; 
    RecyclerView.Adapter mAdapter; 
    ArrayList<NatureItem> actorsList; 

    private int previousTotal = 0; 
    private boolean loading = true; 
    private int visibleThreshold = 5; 
    int firstVisibleItem, visibleItemCount, totalItemCount; 

    public static RecyclerViewFragment newInstance() { 
     return new RecyclerViewFragment(); 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     return inflater.inflate(R.layout.fragment_recyclerview_advance, container, false); 
    } 

    @Override 
    public void onViewCreated(View view, Bundle savedInstanceState) { 
     super.onViewCreated(view, savedInstanceState); 

     actorsList = new ArrayList<NatureItem>(); 

     new JSONAsyncTask().execute("my JSON url"); 

     mRecyclerView = (RecyclerView) view.findViewById(R.id.recycler_view); 
     mRecyclerView.setHasFixedSize(true); 

     mLayoutManager = new GridLayoutManager(getActivity(), 2); 
     mRecyclerView.setLayoutManager(mLayoutManager); 

     mRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() { 

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

       visibleItemCount = mRecyclerView.getChildCount(); 
       totalItemCount = mLayoutManager.getItemCount(); 
       firstVisibleItem = mLayoutManager.findFirstVisibleItemPosition(); 

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

        Log.i("...", "end called"); 

        // Do something 

        loading = true; 
       } 
      } 
     }); 

     // mAdapter = new CardAdapter(); 
     mAdapter = new RecyclerViewMaterialAdapter(new CardAdapter(getActivity(), actorsList), 2); 
     mRecyclerView.setAdapter(mAdapter); 

     MaterialViewPagerHelper.registerRecyclerView(getActivity(), mRecyclerView, null); 

     mRecyclerView.addOnItemTouchListener(
       new RecyclerItemClickListener(getActivity(), new RecyclerItemClickListener.OnItemClickListener() { 
        @Override 
        public void onItemClick(View view, int position) { 

         Toast.makeText(getActivity(), String.valueOf(position), Toast.LENGTH_LONG).show(); 

        } 
       }) 
     ); 

    } 

    class JSONAsyncTask extends AsyncTask<String, Void, Boolean> { 

     ProgressDialog dialog; 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
      dialog = new ProgressDialog(getActivity()); 
      dialog.setMessage("Loading, please wait"); 
      dialog.setTitle("Connecting server"); 
      dialog.show(); 
      dialog.setCancelable(false); 
     } 

     @Override 
     protected Boolean doInBackground(String... urls) { 
      try { 

       //------------------>> 
       HttpGet httppost = new HttpGet(urls[0]); 
       HttpClient httpclient = new DefaultHttpClient(); 
       HttpResponse response = httpclient.execute(httppost); 

       // StatusLine stat = response.getStatusLine(); 
       int status = response.getStatusLine().getStatusCode(); 

       if (status == 200) { 
        HttpEntity entity = response.getEntity(); 
        String data = null; 
        try { 
         data = EntityUtils.toString(entity); 
        } catch (IOException e) { 
         e.printStackTrace(); 
        } 


        JSONObject jsono = null; 
        try { 
         jsono = new JSONObject(data); 
        } catch (JSONException e) { 
         e.printStackTrace(); 
        } 
        JSONArray jarray = jsono.getJSONArray("wallpapers"); 


        for (int i = 0; i < jarray.length(); i++) { 
         JSONObject object = jarray.getJSONObject(i); 

         NatureItem actor = new NatureItem(); 

         actor.setName(object.getString("id")); 
         actor.setThumbnail(object.getString("thumb_url")); 

         actorsList.add(actor); 
        } 
        return true; 
       } 

       //------------------>> 

      } catch (ParseException e1) { 
       e1.printStackTrace(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } catch (JSONException e) { 
       e.printStackTrace(); 
      } 
      return false; 
     } 

     protected void onPostExecute(Boolean result) { 
      dialog.cancel(); 
      mAdapter.notifyDataSetChanged(); 
      if (result == false) { 
       Toast.makeText(getActivity(), "Unable to fetch data from server", Toast.LENGTH_LONG).show(); 
      } 
      else { 

      } 

     } 
    } 
} 

CardAdapter.java:

public class CardAdapter extends RecyclerView.Adapter<CardAdapter.ViewHolder> { 

    private ArrayList<NatureItem> mItems; 
    private Context mContext; 

    public CardAdapter(Context context, ArrayList<NatureItem> feedItemList) { 
     this.mItems = feedItemList; 
     this.mContext = context; 
    } 

    @Override 
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) { 
     View v = LayoutInflater.from(viewGroup.getContext()) 
       .inflate(R.layout.recycler_view_card_item, viewGroup, false); 

     ViewHolder viewHolder = new ViewHolder(v); 
     return viewHolder; 
    } 

    @Override 
    public void onBindViewHolder(ViewHolder viewHolder, int i) { 
     NatureItem nature = mItems.get(i); 
     viewHolder.tvNature.setText(nature.getName()); 

     Picasso.with(mContext).load(nature.getThumbnail()) 
       .error(R.mipmap.ic_launcher) 
       .placeholder(R.mipmap.ic_launcher) 
       .into(viewHolder.imgThumbnail); 

    } 

    @Override 
    public int getItemCount() { 
     return mItems.size(); 
    } 

    class ViewHolder extends RecyclerView.ViewHolder{ 

     public ImageView imgThumbnail; 
     public TextView tvNature; 

     public ViewHolder(View itemView) { 
      super(itemView); 
      imgThumbnail = (ImageView)itemView.findViewById(R.id.img_thumbnail); 
      tvNature = (TextView)itemView.findViewById(R.id.tv_nature); 
     } 
    } 
} 

Hier ist, wie ich auch Endlose umgesetzt haben, mit this:

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

Hinweis: Ich persönlich würde RecyclerView onScroll-Funktionalität bevorzugen, um meine Arbeit zu erledigen.

Answer 1

Aktivität Klasse mit recylcerview in XML-Layout-Datei

public class WallpaperActivity extends AppCompatActivity implements OnTaskCompleted { 


private static final String TAG = "WallpaperActivity"; 


private Toolbar toolbar; 


private RecyclerView mRecyclerView; 
private WallPaperDataAdapter mAdapter; 
private LinearLayoutManager mLayoutManager; 
// to keep track which pages loaded and next pages to load 
public static int pageNumber; 

private List<WallPaper> wallpaperImagesList; 


protected Handler handler; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.wallpaper_main); 
    toolbar = (Toolbar) findViewById(R.id.toolbar); 
    mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view); 
    pageNumber = 1; 
    wallpaperImagesList = new ArrayList<WallPaper>(); 
    handler = new Handler(); 
    if (toolbar != null) { 
     setSupportActionBar(toolbar); 
     getSupportActionBar().setTitle("WallPapers"); 

    } 


    // use this setting to improve performance if you know that changes 
    // in content do not change the layout size of the RecyclerView 
    mRecyclerView.setHasFixedSize(true); 


    mLayoutManager = new LinearLayoutManager(this); 


    // use a linear layout manager 
    mRecyclerView.setLayoutManager(mLayoutManager); 


    // create an Object for Adapter 
    mAdapter = new WallPaperDataAdapter(wallpaperImagesList, mRecyclerView); 

    // set the adapter object to the Recyclerview 
    mRecyclerView.setAdapter(mAdapter); 


    getWebServiceData(); 


    mAdapter.setOnLoadMoreListener(new OnLoadMoreListener() { 
     @Override 
     public void onLoadMore() { 
      //add null , so the adapter will check view_type and show progress bar at bottom 
      wallpaperImagesList.add(null); 
      mAdapter.notifyItemInserted(wallpaperImagesList.size() - 1); 
      ++pageNumber; 


      getWebServiceData(); 


     } 
    }); 


} 


public void getWebServiceData() { 

    BackGroundTask backGroundTask = new BackGroundTask(this, this, pageNumber); 
    backGroundTask.execute(); 

} 


@Override 
public void onTaskCompleted(String response) { 


    parsejosnData(response); 

} 


public void parsejosnData(String response) { 

    try { 

     JSONObject jsonObject = new JSONObject(response); 

     // String json = jsonObject.toString(); 

     JSONArray jsonArray = jsonObject.getJSONArray("wallpapers"); 


     if (jsonArray != null) { 
      // looping through All albums 


      if (pageNumber > 1) { 
       wallpaperImagesList.remove(wallpaperImagesList.size() - 1); 
       mAdapter.notifyItemRemoved(wallpaperImagesList.size()); 
      } 

      for (int i = 0; i < jsonArray.length(); i++) { 
       JSONObject c = jsonArray.getJSONObject(i); 

       // Storing each json item values in variable 
       String id = c.getString("id"); 
       String orig_url = c.getString("orig_url"); 
       String thumb_url = c.getString("thumb_url"); 
       String downloads = c.getString("downloads"); 
       String fav = c.getString("fav"); 

       // Creating object for each product 
       WallPaper singleWall = new WallPaper(id, orig_url, thumb_url, downloads, fav); 

       // adding HashList to ArrayList 
       wallpaperImagesList.add(singleWall); 


       handler.post(new Runnable() { 
        @Override 
        public void run() { 
         mAdapter.notifyItemInserted(wallpaperImagesList.size()); 


        } 
       }); 


      } 


      mAdapter.setLoaded(); 


     } else { 
      Log.d("Wallpapers: ", "null"); 
     } 

    } catch (JSONException e) { 
     e.printStackTrace(); 
    } 

} 


} 

Adapter Klasse

public class WallPaperDataAdapter extends RecyclerView.Adapter { 
    private final int VIEW_ITEM = 1; 
    private final int VIEW_PROG = 0; 

    private List<WallPaper> imagesList; 

    // The minimum amount of items to have below your current scroll position 
    // before loading more. 
    private int visibleThreshold = 5; 
    private int lastVisibleItem, totalItemCount; 
    private boolean loading; 
    private OnLoadMoreListener onLoadMoreListener; 


    public WallPaperDataAdapter(List<WallPaper> imagesList1, RecyclerView recyclerView) { 
     imagesList = imagesList1; 

     if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) { 

      final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView 
        .getLayoutManager(); 


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

          totalItemCount = linearLayoutManager.getItemCount(); 
          lastVisibleItem = linearLayoutManager 
            .findLastVisibleItemPosition(); 
          if (!loading 
            && totalItemCount <= (lastVisibleItem + visibleThreshold)) { 
           // End has been reached 
           // Do something 
           if (onLoadMoreListener != null) { 
            onLoadMoreListener.onLoadMore(); 
           } 
           loading = true; 
          } 
         } 
        }); 
     } 
    } 

    @Override 
    public int getItemViewType(int position) { 
     return imagesList.get(position) != null ? VIEW_ITEM : VIEW_PROG; 
    } 

    @Override 
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, 
                 int viewType) { 
     RecyclerView.ViewHolder vh; 
     if (viewType == VIEW_ITEM) { 
      View v = LayoutInflater.from(parent.getContext()).inflate(
        R.layout.wallpaper_row, parent, false); 

      vh = new WallPaperViewHolder(v); 
     } else { 
      View v = LayoutInflater.from(parent.getContext()).inflate(
        R.layout.progress_item, parent, false); 

      vh = new ProgressViewHolder(v); 
     } 
     return vh; 
    } 

    @Override 
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) { 
     if (holder instanceof WallPaperViewHolder) { 

      WallPaper singleWallPaper = (WallPaper) imagesList.get(position); 


      Glide.with(((WallPaperViewHolder) holder).thumbIcon.getContext()) 
        .load(singleWallPaper.getThumbUrl()) 
        .centerCrop() 
        .placeholder(R.drawable.bg) 
        .crossFade() 
        .into(((WallPaperViewHolder) holder).thumbIcon); 


     } else { 
      ((ProgressViewHolder) holder).progressBar.setIndeterminate(true); 
     } 
    } 

    public void setLoaded() { 
     loading = false; 
    } 

    @Override 
    public int getItemCount() { 
     return imagesList.size(); 
    } 

    public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) { 
     this.onLoadMoreListener = onLoadMoreListener; 
    } 


    // 
    public static class WallPaperViewHolder extends RecyclerView.ViewHolder { 


     public ImageView thumbIcon; 


     public WallPaperViewHolder(View v) { 
      super(v); 


      thumbIcon = (ImageView) v.findViewById(R.id.thumbIcon); 


     } 
    } 

    public static class ProgressViewHolder extends RecyclerView.ViewHolder { 
     public ProgressBar progressBar; 

     public ProgressViewHolder(View v) { 
      super(v); 
      progressBar = (ProgressBar) v.findViewById(R.id.progressBar1); 
     } 
    } 
} 

wallpaper_row.xml

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content"> 

<ImageView 
    android:id="@+id/thumbIcon" 
    android:layout_width="160dp" 
    android:layout_height="160dp" 
    android:layout_centerInParent="true" 
    android:layout_margin="2dp" 
    android:gravity="center" /> 

</RelativeLayout> 

progress_item.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="wrap_content" 
    android:orientation="vertical" > 

    <ProgressBar 
     android:id="@+id/progressBar1" 
     android:layout_width="wrap_content" 
     android:layout_gravity="center" 
     android:layout_height="wrap_content" /> 

</LinearLayout> 

Separate BackGroundTask.java

public class BackGroundTask extends AsyncTask<Object, Void, String> { 

    private ProgressDialog pDialog; 
    public OnTaskCompleted listener = null;//Call back interface 


    Context context; 
    int pageNumber; 

    public BackGroundTask(Context context1, OnTaskCompleted listener1, int pageNumber) { 
     context = context1; 
     listener = listener1; //Assigning call back interface through constructor 
     this.pageNumber = pageNumber; 
    } 

    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 

    } 

    @Override 
    protected String doInBackground(Object... params) { 

     //My Background tasks are written here 

     synchronized (this) { 

      String url = Const.URL_WALLPAPERS_HD + pageNumber; 
      String jsonStr = ServiceHandler.makeServiceCall(url, ServiceHandler.GET); 
      Log.i("Url: ", "> " + url); 

      Log.i("Response: ", "> " + jsonStr); 
      return jsonStr; 
     } 

    } 

    @Override 
    protected void onPostExecute(String result) { 
     super.onPostExecute(result); 
     listener.onTaskCompleted(result); 

    } 

} 

ServiceHanlder.java

public class ServiceHandler { 

    static String response = null; 
    public final static int GET = 1; 
    public final static int POST = 2; 


    public ServiceHandler() { 

    } 

    /** 
    * Making service call 
    * 
    * @url - url to make request 
    * @method - http request method 
    */ 
    public static String makeServiceCall(String url, int method) { 
     return makeServiceCall(url, method, null); 
    } 

    /** 
    * Making service call 
    * 
    * @url - url to make request 
    * @method - http request method 
    * @params - http request params 
    */ 
    public static String makeServiceCall(String url, int method, 
            List<NameValuePair> params) { 
     try { 
      // http client 
      DefaultHttpClient httpClient = new DefaultHttpClient(); 
      HttpEntity httpEntity = null; 
      HttpResponse httpResponse = null; 

      // Checking http request method type 
      if (method == POST) { 
       HttpPost httpPost = new HttpPost(url); 
       // adding post params 
       if (params != null) { 
        httpPost.setEntity(new UrlEncodedFormEntity(params)); 
       } 
       Log.e("Selltis Request URL", url); 
       httpResponse = httpClient.execute(httpPost); 

      } else if (method == GET) { 
       // appending params to url 
       if (params != null) { 
        String paramString = URLEncodedUtils 
          .format(params, "utf-8"); 
        url += paramString; 

        Log.i("Request URL", url); 
       } 
       HttpGet httpGet = new HttpGet(url); 

       httpResponse = httpClient.execute(httpGet); 

      } 
      httpEntity = httpResponse.getEntity(); 
      response = EntityUtils.toString(httpEntity); 

     } catch (UnsupportedEncodingException e) { 
      e.printStackTrace(); 
      return "Fail"; 
     } catch (ClientProtocolException e) { 
      e.printStackTrace(); 
      return "Fail"; 
     } catch (IOException e) { 
      e.printStackTrace(); 
      return "Fail"; 
     } 

     return response; 

    } 


} 

Schnittstelle für Last Mehr

public interface OnLoadMoreListener { 
    void onLoadMore(); 
} 

Schnittstelle Web-Service-Daten von AsyncTask geladen wissen

public interface OnTaskCompleted{ 

    void onTaskCompleted(String response); 
} 

Bitte lassen Sie mich wissen, wenn das funktioniert oder irgendwelche Probleme für Sie. Besser, Volley oder okHttp Libraries für Networking zu verwenden.

Für ImageLoading habe ich Glide Bibliothek verwendet.

Answer 2

Im OnScroll Methode

if (!loading && (totalItemCount - visibleItemCount) 
     <= (firstVisibleItem + visibleThreshold)) { 
    // End has been reached 

    Log.i("...", "end called"); 

    // Do something 
    new JSONAsyncTask().execute("http://walldroidhd.com/api.php"); 

    loading = true; 
} 

Answer 3

Die Idee Last mehr zu realisieren ist:

alle Datensätze in einer Sammlung holen. Nehmen Sie eine andere Sammlung, die Teilsätze füllt, sagen wir 10 Datensätze. Wenn Sie unten angekommen sind, füllen Sie die nächsten 10 Datensätze in der Sammlung aus und benachrichtigen Sie die Liste.

So wird Ihr Code so etwas wie dieses:

ArrayList<NatureItem> tempList; // which holds partial records 
tempList = getList(limit, 10); 

mAdapter = new RecyclerViewMaterialAdapter(new CardAdapter(getActivity(), tempList), 2); 
mRecyclerView.setAdapter(mAdapter); 

Nun Code nächste Datensätze laden:

limit += 10; 
tempList.addAll(getList(limit, 10)); 
mAdapter.notifyDataSetChanged(); 

zeigen, dass er loader/Fortschritt, besser zu nutzen load-more library

Answer 4

So erkenne ich, ob RecyclerView von OnScrollListener aktualisiert werden sollte, schauen Sie es:

recyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() { 
    int ydy = 0; 
    @Override 
    public void onScrollStateChanged(RecyclerView recyclerView, int newState) { 
     super.onScrollStateChanged(recyclerView, newState); 

    } 

    @Override 
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) { 
     super.onScrolled(recyclerView, dx, dy); 
     int offset = dy - ydy; 
     ydy = dy; 
     boolean shouldRefresh = (linearLayoutManager.findFirstCompletelyVisibleItemPosition() == 0) 
       && (recyclerView.getScrollState() == RecyclerView.SCROLL_STATE_DRAGGING) && offset > 30; 
     if (shouldRefresh) { 
      //swipeRefreshLayout.setRefreshing(true); 
      //Refresh to load data here. 
      return; 
     } 
     boolean shouldPullUpRefresh = linearLayoutManager.findLastCompletelyVisibleItemPosition() == linearLayoutManager.getChildCount() - 1 
       && recyclerView.getScrollState() == RecyclerView.SCROLL_STATE_DRAGGING && offset < -30; 
     if (shouldPullUpRefresh) { 
      //swipeRefreshLayout.setRefreshing(true); 
      //refresh to load data here. 
      return; 
     } 
     swipeRefreshLayout.setRefreshing(false); 
    } 
}); 

Hoffe, dass Sie inspiriert werden.Viel Glück ~

Answer 5

Ein anderes Beispiel. Setze unten deinen Fortschrittsbalken und ändere die Sichtbarkeit entsprechend dem Scrollen/Laden und deinen Datensätzen. Hinweis: Sie müssen notifyDataSetChanged(); Verfahren zum Hinzufügen/Refresh-Daten

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

       int total = linearLayoutManager.getItemCount(); 
       int firstVisibleItemCount = linearLayoutManager.findFirstVisibleItemPosition(); 
       int lastVisibleItemCount = linearLayoutManager.findLastVisibleItemPosition(); 

       //to avoid multiple calls to loadMore() method 
       //maintain a boolean value (isLoading). if loadMore() task started set to true and completes set to false 
       if (!isLoading) { 
        if (total > 0) 
         if ((total - 1) == lastVisibleItemCount){ 
          loadMore();//your HTTP stuff goes in this method 
          loadingProgress.setVisibility(View.VISIBLE); 
         }else 
          loadingProgress.setVisibility(View.GONE); 
       } 
      } 

      @Override 
      public void onScrollStateChanged(RecyclerView recyclerView, int newState) { 
       super.onScrollStateChanged(recyclerView, newState); 

      } 

    });