Paginierung in Recyclerview in Android

Question

Ich versuche Paginierung in Recyclerview zu implementieren. Im Folgenden sind meine Java-Klassen:

MyAdapter.java

package com.example.opinion; 

import android.support.v7.widget.RecyclerView; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 

import java.util.ArrayList; 
import java.util.List; 


/** 
* Created by manish on 7/18/2016. 
*/ 
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> { 
    private ArrayList<String> movieName = new ArrayList(); 


    public MyAdapter(ArrayList film) 
    { 
     this.movieName = film; 
    } 

    @Override 
    public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, 
                int viewType) { 
     // create a new view 
     View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_items, null); 
     // set the view's size, margins, paddings and layout parameters 
     ViewHolder vh = new ViewHolder(v); 
     return vh; 
    } 
    @Override 
    public void onBindViewHolder(ViewHolder holder, int position) { 
     // - get element from your dataset at this position 
     // - replace the contents of the view with that element 
     holder.movieText.setText(movieName.get(position)); 



    } 

    // Return the size of your dataset (invoked by the layout manager) 
    @Override 
    public int getItemCount() 
    { 
     System.out.print(movieName.size()); 
     return movieName.size(); 
    } 

    public class ViewHolder extends RecyclerView.ViewHolder { 
     // each data item is just a string in this case 
     public TextView movieText; 

     public ViewHolder(View v) { 
      super(v); 
      movieText = (TextView) v.findViewById(R.id.movieName); 
     } 
    } 

} 

viewfragment.java: Hier bin ich die Daten auf meinem lokalen Netzwerk abgerufen werden. In dieser Datei ruft die Funktion loadMore (current_page) nur 3 Werte zur Zeit ab. Beim erstmaligen Aufruf werden diese drei Werte nur in der Ansicht cardview in recycling angezeigt. Ich weiß nicht wo das Problem ist!

package com.example.opinion; 



import java.lang.reflect.Type; 
import java.util.ArrayList; 
import java.util.List; 

import org.w3c.dom.Text; 

import android.content.Context; 
import android.content.Intent; 
import android.content.SharedPreferences; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.util.Log; 
import android.view.Gravity; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.content.Intent; 
import android.widget.Button; 
import android.widget.TextView; 
import android.widget.Toast; 

import retrofit2.Call; 
import retrofit2.Callback; 
import retrofit2.Response; 
import retrofit2.Retrofit; 
import retrofit2.converter.gson.GsonConverterFactory; 
import retrofit2.http.GET; 
import retrofit2.http.Path; 


public class ViewFragment extends Fragment { 

    private static final String PREFS_NAME = "Prefname"; 



    public int j =0; 
    static String quesText; 


    //public static final String BASE_URL = "http://192.168.0.104/"; 

    public interface PostquesApi{ 
     @GET("ques/{i}") 
     Call<quesGetResponse> quesget(@Path("i") String i); 
    } 

    static class quesGetResponse { 

     String ques1; 
     String ques2; 
     String ques3; 
     String quid1; 
     String quid2; 
     String quid3; 

     public quesGetResponse(String ques1, String ques2, String ques3, String u1, String u2,String u3){ 
      this.ques1 = ques1; 
      this.ques2 = ques2; 
      this.ques3 = ques3; 
      this.quid1 = u1; 
      this.quid2 = u2; 
      this.quid3 = u3; 
      } 
    } 
    //View rootView; 
    private RecyclerView mRecyclerView; 
    private RecyclerView.Adapter mAdapter; 

    private ArrayList movieList = new ArrayList(); 
    private static int current_page = 1; 




    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 

     final View rootView = inflater.inflate(R.layout.fragment_view, container, false); 

     for(int k=0; k<2; k++) { 
      loadData(current_page); 
     } 
     System.out.println("contents of movie list: "+ movieList); 

     mRecyclerView = (RecyclerView) rootView.findViewById(R.id.my_recycler_view); 

     // 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); 

     // use a linear layout manager 
     LinearLayoutManager feedLayoutManager = new LinearLayoutManager(getActivity()); 
     mAdapter = new MyAdapter(movieList); 
     mRecyclerView.setAdapter(mAdapter); 
     mRecyclerView.setLayoutManager(feedLayoutManager); 

     // specify an adapter (see also next example) 

     mRecyclerView.addOnScrollListener(new EndlessRecyclerOnScrollListener(
       feedLayoutManager) { 
      @Override 
      public void onLoadMore(int current_page) { 
       // do somthing... 

       loadMoreData(current_page); 

      } 

     }); 

     /*qt2.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent comm = new Intent(getActivity(), Comments.class); 
       quesText = qt2.getText().toString(); 

       //comm.putExtra(quesText, Text); 
       startActivity(comm); 
      } 
     }); 
     qt3.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent comm = new Intent(getActivity(), Comments.class); 
       quesText = qt3.getText().toString(); 

       //comm.putExtra(quesText, Text); 
       startActivity(comm); 
      } 
     });*/ 

     return rootView; 

    } 
    public void loadData(int page) { 
     // Send an API request to retrieve appropriate data using the offset value as a parameter. 
     // --> Deserialize API response and then construct new objects to append to the adapter 
     // --> Notify the adapter of the changes 
     Retrofit retrofit = new Retrofit.Builder() 
       .baseUrl(Login.BASE_URL) 
       .addConverterFactory(GsonConverterFactory.create()) 
       .build(); 

     PostquesApi apiService = retrofit.create(PostquesApi.class); 
     Call<quesGetResponse> call = apiService.quesget(Integer.toString(j)); 
     call.enqueue(new Callback<quesGetResponse>() { 
      @Override 
      public void onResponse(Call<quesGetResponse> call, Response<quesGetResponse> response) { 
       quesGetResponse decodedResponse = response.body(); 
       if (decodedResponse != null) { 
        if (decodedResponse.ques1 != null && decodedResponse.quid1.compareTo(Login.user_id) != 0) 
        { 
         movieList.add(decodedResponse.ques1); 
        } 
        if (decodedResponse.ques2 != null && decodedResponse.quid2.compareTo(Login.user_id) != 0) 
        { 
         movieList.add(decodedResponse.ques2); 
        } 
        if (decodedResponse.ques3 != null && decodedResponse.quid3.compareTo(Login.user_id) != 0) 
        { 
         movieList.add(decodedResponse.ques3); 
        } 
       } 

       if (decodedResponse.ques1 == null || decodedResponse.ques2 == null || decodedResponse.ques3 == null) { 
        Context context = getActivity().getApplicationContext(); 
        CharSequence text = "Sorry!! no more questions in the database..."; 
        int duration = Toast.LENGTH_SHORT; 

        Toast toast = Toast.makeText(context, text, duration); 
        toast.show(); 
       } 

       j = j + 3; 
      } 

      @Override 
      public void onFailure(Call<quesGetResponse> call, Throwable t) { 

      } 
     }); 
    } 
    private void loadMoreData(int current_page) { 

     Retrofit retrofit = new Retrofit.Builder() 
       .baseUrl(Login.BASE_URL) 
       .addConverterFactory(GsonConverterFactory.create()) 
       .build(); 

     PostquesApi apiService = retrofit.create(PostquesApi.class); 
     Call<quesGetResponse> call = apiService.quesget(Integer.toString(j)); 
     call.enqueue(new Callback<quesGetResponse>() { 
      @Override 
      public void onResponse(Call<quesGetResponse> call, Response<quesGetResponse> response) { 
       quesGetResponse decodedResponse = response.body(); 
       if (decodedResponse != null) { 
        if (decodedResponse.ques1 != null && decodedResponse.quid1.compareTo(Login.user_id) != 0) 
        { 
         movieList.add(decodedResponse.ques1); 
        } 
        if (decodedResponse.ques2 != null && decodedResponse.quid2.compareTo(Login.user_id) != 0) 
        { 
         movieList.add(decodedResponse.ques2); 
        } 
        if (decodedResponse.ques3 != null && decodedResponse.quid3.compareTo(Login.user_id) != 0) 
        { 
         movieList.add(decodedResponse.ques3); 
        } 
       } 

       if (decodedResponse.ques1 == null || decodedResponse.ques2 == null || decodedResponse.ques3 == null) { 
        Context context = getActivity().getApplicationContext(); 
        CharSequence text = "Sorry!! no more questions in the database..."; 
        int duration = Toast.LENGTH_SHORT; 

        Toast toast = Toast.makeText(context, text, duration); 
        toast.show(); 
       } 

       j = j + 3; 
      } 

      @Override 
      public void onFailure(Call<quesGetResponse> call, Throwable t) { 

      } 
     }); 



     mAdapter.notifyDataSetChanged(); 

    } 

} 

EndlessRecyclerOnScrollListener.java: Die Datei, die die Logik für die Paginierung implementiert.

package com.example.opinion; 

import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 

/** 
* Created by manish on 7/20/2016. 
*/ 

public abstract class EndlessRecyclerOnScrollListener extends 
     RecyclerView.OnScrollListener { 
    public static String TAG = EndlessRecyclerOnScrollListener.class 
      .getSimpleName(); 

    private int previousTotal = 0; 
    private boolean loading = true; 
    private int visibleThreshold = 3; 
    int firstVisibleItem, visibleItemCount, totalItemCount; 

    private int current_page = 1; 

    private LinearLayoutManager mLinearLayoutManager; 

    public EndlessRecyclerOnScrollListener(
      LinearLayoutManager linearLayoutManager) { 
     this.mLinearLayoutManager = linearLayoutManager; 
    } 

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

     visibleItemCount = recyclerView.getChildCount(); 
     totalItemCount = mLinearLayoutManager.getItemCount(); 
     firstVisibleItem = mLinearLayoutManager.findFirstVisibleItemPosition(); 

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

      // Do something 
      current_page++; 

      onLoadMore(current_page); 

      loading = true; 
     } 
    } 

    public abstract void onLoadMore(int current_page); 
} 

Wenn jemand es überprüfen und sagen Sie mir, die in den oben genannten Dateien erforderlichen Korrekturen oder kann mich bis zu einem gewissen Ressource lenkt, wird es wirklich geschätzt.

Answer 1

Ich würde vorschlagen, statt EndlessRecyclerOnScrollListener Klasse und hören auf die Scroll-Ereignis Recyclerview sollten Sie in MyAdapter Klasse zu sehen.

. Fügen Sie zunächst eine Schnittstelle

public interface GetNewDataEvents { 
     void getNewAdapterData(); 
    } 

. Initialisieren Sie diese Schnittstelle in der MyAdapter-Klasse, von der Sie Ihre Daten hinzufügen, indem Sie sie implementieren.

. finden Sie leicht, welche in bindViewHolder wird derzeit Artikel Laden mit

if(position==(movieName.size()-1) 

und in ihm können Sie leicht, dass die Interface-Methode aufrufen und neue Daten darin laden.

Dieses Ding zeigt an, dass das zweitletzte Objekt gerade geladen wird und Sie sollten neue Daten hinzufügen, falls vorhanden.

Wenn Sie neue Daten erhalten, können Sie sie einfach in Ihren Adapter laden und notifyItemRangeChanged damit aufrufen, um Leistung zu erhalten und Best Practices zu implementieren, indem Sie den ganzen Adapter nicht mit nur wenigen geänderten Elementen laden.

wenn Sie es nehmen Bezug möchten, können Sie gehen here