自定义适配器内的Android Refresh RecyclerView

Question

我有一个使用自定义适配器的回收站视图。 我在自定义适配器上有一个按钮，用于在单击时从数据库中删除一行。 这工作正常但我现在希望视图从服务器更新并向用户显示他们删除的行。 我将在下面发布的代码没有给出任何错误，但没有正确刷新。 我也会附上我的班级和适配器。 谢谢。

MyReviews.Java

public class MyReviews extends AppCompatActivity {
    private ArrayList reviewername;
    private ArrayList reviewscore;
    private ArrayList reviewerpic;
    private ArrayList reviewdate;
    private ArrayList reviewtext;
    private ArrayList reviewid;
    private static String url;
    private String TAG = SearchScreen.class.getSimpleName();
    private ProgressDialog pDialog;
    private String userid;

    SessionManagement session;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        reviewername = new ArrayList<>();
        reviewscore = new ArrayList<>();
        reviewerpic = new ArrayList<>();
        reviewdate = new ArrayList<>();
        reviewtext = new ArrayList<>();
        reviewid = new ArrayList<>();
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my_reviews);
        setTitle("My Reviews");
        session = new SessionManagement(getApplicationContext());
        HashMap<String, String> user = session.getUserDetails();
        userid = user.get(SessionManagement.KEY_ID);
        url = "url" + userid;
        Log.d("URL", url);
        initViews();
    }

    private void initViews() {
        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.myreviewslist);
        recyclerView.setHasFixedSize(true);
        RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext());
        recyclerView.setLayoutManager(layoutManager);
        new GetMyReviews().execute();
    }

    private class GetMyReviews extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Showing progress dialog
            pDialog = new ProgressDialog(MyReviews.this);
            pDialog.setMessage("Please Wait..");
            pDialog.setCancelable(false);
            pDialog.show();

        }

        @Override
        protected Void doInBackground(Void... arg0) {
            HttpHandler sh = new HttpHandler();

            // Making a request to url and getting response
            String jsonStr = sh.makeServiceCall(url);

            Log.e(TAG, "Response from url: " + jsonStr);

            if (jsonStr != null) {
                try {
                    JSONObject jsonObj = new JSONObject(jsonStr);

                    // Getting JSON Array node
                    JSONArray contacts = jsonObj.getJSONArray("MyGeek");

                    // looping through All Contacts
                    for (int i = 0; i < contacts.length(); i++) {
                        JSONObject c = contacts.getJSONObject(i);

                        reviewername.add(c.getString("reviewername"));
                        reviewscore.add(c.getString("reviewscore"));
                        reviewerpic.add(c.getString("reviewerpic"));
                        reviewdate.add(c.getString("reviewdate"));
                        reviewtext.add(c.getString("reviewtext"));
                        reviewid.add(c.getString("reviewid"));


                    }
                } catch (final JSONException e) {
                    Log.e(TAG, "Json parsing error: " + e.getMessage());
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            Toast.makeText(getApplicationContext(),
                                    "Json parsing error: " + e.getMessage(),
                                    Toast.LENGTH_LONG)
                                    .show();
                        }
                    });

                }
            } else {
                Log.e(TAG, "Couldn't get json from server.");
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(),
                                "Couldn't get json from server. Check LogCat for possible errors!",
                                Toast.LENGTH_LONG)
                                .show();
                    }
                });

            }

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            pDialog.hide();

            RecyclerView recyclerView = (RecyclerView) findViewById(R.id.myreviewslist);

            RecyclerView.Adapter adapter = new DataAdapterMyReviews(reviewername, reviewscore, reviewerpic, reviewdate, reviewtext, reviewid);
            recyclerView.setAdapter(adapter);


        }
    }
}

DataAdapterMyReviews.Java

public class DataAdapterMyReviews extends RecyclerView.Adapter<DataAdapterMyReviews.ViewHolder> {
    private ArrayList<String> reviewername;
    private ArrayList<String> reviewscore;
    private ArrayList<String> reviewerpic;
    private ArrayList<String> reviewdate;
    private ArrayList<String> reviewtext;
    private ArrayList<String> reviewid;
    private static String url;
    private String TAG = SearchScreen.class.getSimpleName();
    private String success = "0";

    public DataAdapterMyReviews(ArrayList<String> reviewername, ArrayList<String> reviewscore, ArrayList<String> reviewerpic, ArrayList<String> reviewdate, ArrayList<String> reviewtext, ArrayList<String> reviewid) {
        this.reviewername = reviewername;
        this.reviewscore = reviewscore;
        this.reviewerpic = reviewerpic;
        this.reviewscore = reviewscore;
        this.reviewdate = reviewdate;
        this.reviewtext = reviewtext;
        this.reviewid = reviewid;

    }
    public void test(){
        this.notifyDataSetChanged();
    }

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

        return new ViewHolder(view);

    }

    @Override
    public void onBindViewHolder(DataAdapterMyReviews.ViewHolder viewHolder, int i) {

        final int num;
        viewHolder.reviewnametext2.setText(reviewername.get(i));
        viewHolder.reviewscoretext2.setText(reviewscore.get(i));
        viewHolder.reviewtext2.setText(reviewtext.get(i));
        viewHolder.reviewdate2.setText(reviewdate.get(i));


        Picasso.with(viewHolder.itemView.getContext())
                .load(reviewerpic.get(i))
                .into(viewHolder.userpicreview2);
        num = i;
        viewHolder.delete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.i("Delete ReviewID: ", reviewid.get(num));
                url = "url" + reviewid.get(num);
                new DeleteReview().execute();

            }
        });


        viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

            }
        });
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder {
        private ImageView userpicreview2;
        private TextView reviewnametext2;
        private TextView reviewscoretext2;
        private TextView reviewtext2;
        private TextView reviewdate2;
        private Button delete;


        public ViewHolder(View view) {
            super(view);

            userpicreview2 = (ImageView) view.findViewById(R.id.userpicreview);
            reviewnametext2 = (TextView) view.findViewById(R.id.reviewnametext);
            reviewscoretext2 = (TextView) view.findViewById(R.id.reviewscoretext);
            reviewtext2 = (TextView) view.findViewById(R.id.reviewtext2);
            reviewdate2 = (TextView) view.findViewById(R.id.reviewdatetext);

            delete = (Button) view.findViewById(R.id.btnDeleteReview);


        }
    }

        private class DeleteReview extends AsyncTask<Void, Void, Void> {

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                // Showing progress dialog


            }

            @Override
            protected Void doInBackground(Void... arg0) {
                HttpHandler sh = new HttpHandler();

                // Making a request to url and getting response
                String jsonStr = sh.makeServiceCall(url);

                Log.e(TAG, "Response from url: " + jsonStr);

                if (jsonStr != null) {
                    try {
                        JSONObject jsonObj = new JSONObject(jsonStr);

                        // Getting JSON Array node
                        JSONArray contacts = jsonObj.getJSONArray("MyGeek");

                        // looping through All Contacts

                            JSONObject c = contacts.getJSONObject(0);

                           success = c.getString("success");




                    } catch (final JSONException e) {
                        Log.e(TAG, "Json parsing error: " + e.getMessage());



                    }
                } else {
                    Log.e(TAG, "Couldn't get json from server.");

                }

                return null;
            }

            @Override
            protected void onPostExecute(Void result) {
                super.onPostExecute(result);

                if(success.equals("1")){

                    Log.d("reviewdelete","success");
                    test();


                }
                else if(success.equals("0")){
                    Log.d("reviewdelete","fail");

                }
            }
        }
    }

Answer 1

您需要通知您的activity有关数据集更改的信息。 关键点是调用adapter object notifyDataSetChanged() 。 您应该修改当前的Activity类以获得适配器的引用。 最好将适配器代码放在activity类的函数中，然后从内部类调用。

创建一个界面，

public interface DataListener {
    void deleteSuccess();
    void deleteError();
}

指定要通知的侦听器，

public class MyReviews extends AppCompatActivity implements DataListener {
...your codes
//you need to implement the interface methods

@Override
public void deleteSuccess(){
  adapter.notifyDataSetChanged();
  Toast.makeText(this, "Successfully deleted",Toast.LENGTH_LONG).show();
}

@Override
public void deleteError(){
  Toast.makeText(this, "Failed to delete",Toast.LENGTH_LONG).show();
}


}

通知听众，

private class DeleteReview extends AsyncTask<Void, Void, Void> {
....your code...

    @Override
    protected void onPostExecute(Void result) {
            super.onPostExecute(result);

            if(success.equals("1")){

                //get the databaseListener object from your Adapter class constructor.

                databaseListener.deleteSuccess();


            }
            else if(success.equals("0")){
                databaseListener.deleteError();

            }
        }

Answer 2

试试这个：在你的内部DeleteReview.onPostExecute()首先调用List.remove(int index)从数据列表中删除项目。 然后调用notifyItemRemoved来刷新recyclerView。

Answer 3

我建议这些改变：

1. 在ViewHolder ClickListener中更改： new DeleteReview(i).execute(); //i is the position of row new DeleteReview(i).execute(); //i is the position of row
2. 将变量添加到ASyncTask类以保存已删除行的位置
3. 在PostExecute中： DataAdapterMyReviews.this.notifyItemRemoved(i); //Position of Deleted Row DataAdapterMyReviews.this.notifyItemRemoved(i); //Position of Deleted Row

顺便说一下，只要您的dataset没有更改，调用notify不会导致View中的任何更改，因此请确保在更改数据库后更改数据集。 例如，删除操作后，请务必执行以下操作：

reviewername.remove(i);
reviewscore.remove(i);
reviewerpic.remove(i);
reviewdate.remove(i);
reviewtext.remove(i);
reviewid.remove(i);

只要Adapter ，上面的变量就是你的模型。在reviewername大小的变化直接导致RecyclerView单元格大小的变化。所以只要这些变量不变，调用notify就不会改变任何东西。