Question

我从适配器（Myadpter）内部有（删除文件操作），删除文件后我无法刷新此适配器，只是删除了文件，屏幕将保持不变，但我需要刷新状态手动按一下，然后重新进入相同的布局，这样我会发现该布局缺少我删除的文件，但是需要退回并重新进入相同的布局才能刷新它。

有人知道为什么notifyDataSetChanged();无法正常工作吗？

package com.example.boc.storage;

import android.app.DownloadManager;
import android.content.Context;
import android.net.Uri;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.example.boc.R;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.storage.FirebaseStorage;

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

import static android.os.Environment.DIRECTORY_DOWNLOADS;
import static com.example.boc.Pdf.pdfDownloader.TAG;

public class MyAdapter extends RecyclerView.Adapter<MyViewHolder> {

    public MainActivity mainActivity;
    public ArrayList<DownModel> downModels;
    RecyclerView mRecyclerView;
    ArrayList<DownModel> downModelArrayList = new ArrayList<>();



    public MyAdapter (MainActivity mainActivity, ArrayList<DownModel> downModels) {
        this.mainActivity = mainActivity;
        this.downModels = downModels;
    }


    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {

        LayoutInflater layoutInflater = LayoutInflater.from(mainActivity.getBaseContext());
        View view = layoutInflater.inflate( R.layout.storage_elements, null, false);


        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final MyViewHolder myViewHolder, final int i) {

        myViewHolder.mName.setText( downModels.get( i ).getName() );
        myViewHolder.deletePdfBtn.setOnClickListener( new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Context context = myViewHolder.mName.getContext();
                if (context != null) {
                    FirebaseFirestore db = FirebaseFirestore.getInstance();
                    FirebaseStorage firebaseStorage = FirebaseStorage.getInstance();
                    String filenamed = (String) myViewHolder.mName.getText();
                    String url = downModels.get( i ).getLink() ;
                    firebaseStorage.getReferenceFromUrl( url ).delete()
                            .addOnSuccessListener( new OnSuccessListener<Void>() {
                                @Override
                                public void onSuccess(Void aVoid) {
                                    Log.d( TAG, "DocumentSnapshot successfully written!" );
                                }
                            } );
                    db.collection( "Storage" ).document( filenamed ).delete()

                            .addOnSuccessListener( new OnSuccessListener<Void>() {
                                @Override
                                public void onSuccess(Void aVoid) {
                                    Log.d( TAG, "DocumentSnapshot successfully written!" );

                                    notifyDataSetChanged();// this method never helped //






                                }
                            } )
                            .addOnFailureListener( new OnFailureListener() {
                                @Override
                                public void onFailure(@NonNull Exception e) {
                                    Log.w( TAG, "Error writing document", e );

                                }
                            } )
                    ;

                } else {
                    return;


                }

            }
        } );




        myViewHolder.mDownload.setOnClickListener( new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                downloadFile( myViewHolder.mName.getContext(), downModels.get( i ).getName(), ".pdf", DIRECTORY_DOWNLOADS, downModels.get( i ).getLink() );
            }
        } );
    }

    public void downloadFile(Context context, String fileName, String fileExtension, String destinationDirectory, String url) {

        DownloadManager downloadmanager = (DownloadManager) context.
                getSystemService(Context.DOWNLOAD_SERVICE);
        Uri uri = Uri.parse(url);
        DownloadManager.Request request = new DownloadManager.Request(uri);

        request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
        request.setDestinationInExternalFilesDir(context, destinationDirectory, fileName + fileExtension);

        downloadmanager.enqueue(request);
    }






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


}

Answer 1

在成功删除之后，您还需要删除该DownModel，然后调用notifyDataSetChanged();，这样：

   public void onSuccess(Void aVoid) {
      Log.d( TAG, "DocumentSnapshot successfully written!" );
      downModels.remove(i);
      notifyDataSetChanged();
   }

Answer 2

尝试一下！

public void onSuccess(Void aVoid) {
      Log.d( TAG, "DocumentSnapshot successfully written!" );
      notifyItemRangeChanged(i, downModels.size());
      downModels.remove(i);
      notifyItemRemoved(i);
   }

删除文件后更新viewadapter

2 个答案: