自定义适配器内的Android刷新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，可以在单击时从数据库中删除一行。这工作正常，但我现在希望从服务器更新视图并向用户显示他们删除的行已消失。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。我将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

您需要将数据集更改通知您的activity。关键是调用adapter object的notifyDataSetChanged()。 您应该修改当前的 Activity 类以具有适配器的引用。最好将适配器代码放在活动类的函数中，然后从内部类调用。

创建一个接口，

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();
}


}

通知监听器，

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DeleteReview.onPostExecute() 首先调用List.remove(int index) 从数据列表中删除项目。之后调用notifyItemRemoved刷新recyclerView。

Answer 3

我建议进行以下更改：

1. 在 ViewHolder ClickListener 中更改： new DeleteReview(i).execute(); //i is the position of row
2. 在 ASyncTask 类中添加一个变量来保存已删除行的位置
3. 在执行后： DataAdapterMyReviews.this.notifyItemRemoved(i); //Position of Deleted Row

顺便说一句，只要您的dataset 没有更改，调用notify 不会导致View 发生任何更改，因此请务必在更改数据库后更改您的数据集。例如删除操作后一定要这样做：

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

只要关注Adapter，以上变量就是你的模型。reviewername 大小的变化直接导致RecyclerView 单元大小的变化。所以只要这些变量不变，调用notify 就赢了'不要改变任何东西..