用户交互后，如何根据 RecyclerView 适配器内服务器的响应更新 TextView？

Question

我试图通过读取服务器的响应来确定用户是否喜欢 post，在 Retrofit.call.enqueue() 中相应地为布尔值赋值并更改 UI's如果为真，则 TextView 值为 +1。我如何在多个回调中保存变量的值并在调用完成后根据它更新 UI？

在 UI 中，我在 RecyclerView 适配器中有两个按钮 (like\dislike)，它们在单击后将数据更新到 MySQL 数据库，我正在尝试更新喜欢或不喜欢的数量用户互动（如果用户尚未投票，则为+1，我通过 Retrofit 调用进行检查）。

我试图在 Adapter class 中为全局变量赋值，但是代码在调用完成之前运行（我假设这是因为 Retrofit 默认情况下在单独的线程中运行）。我还尝试在 onPostExecute() 方法中更新 AsyncTask 中的 UI，如下所示：

private class LoadDataAsyncTask extends AsyncTask<String, Void, Boolean> {

        //variable to be updated based on response
        boolean voted = true;

        public LoadDataAsyncTask() {
            //todo
        }

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

            Log.v("Voted state start", String.valueOf(voted));
            GetUserVotes mApiGetUserVotes;
            mApiGetUserVotes = ApiUtils.getAPIServiceUserVotes();
            mApiGetUserVotes.getVotes().enqueue(new Callback<ResultVotes>() {
                    @Override
                    public void onResponse(Call<ResultVotes> call, Response<ResultVotes> response) {
                        if(response.body().getSuccess()==1)
                            voted = true;
                        else
                            voted = false;
                        if(!voted){
                            //todo
                        } else {
                            Log.v("Voted", String.valueOf(voted));
                            //todo
                        }
                    }

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

                    }
                });
            Log.v("Voted state end", String.valueOf(voted));
            return voted;
        }

        @Override
        protected void onPostExecute(Boolean result) {
            Log.v("Voted state", String.valueOf(result));
            if(result) {
                //todo

            } else {
                //update UI TextView to +1 vote
                Log.v("onPostExecution", "Triggered");
            }
        }

    }

结果是：

1. V/Voted state start: false
2. V/Voted state end: false
3. V/Voted state: false
4. V/onPostExecution: Triggered
5. V/Voted: true

应该看起来像（如果投票）：

1. false
2. true
3. true
4. Triggered
5. true

我也尝试过这样的界面：

public interface ResponseListener {

    void onSuccess();

    void onFail();
}

并在适配器 class 中实现它（如果未投票则为 onFail()）：

 @Override
    public void onBindViewHolder(final NewsViewHolder holder, int position) {

        final int iLikes = list.get(position).getPositiveVotes();
        final int iDislikes = list.get(position).getNegativeVotes();
        final ResponseListener retrofitResponseListener = new ResponseListener() {
            @Override
            public void onSuccess() {

            }

            @Override
            public void onFail() {
                int x = iNegativeVotes + 1;
                holder.textViewDislike.setText(String.valueOf(x));
            }
        };

    }

这是代码片段：

 @Override
    public void onBindViewHolder(final NewsViewHolder holder, int position) {

        final int iLikes = list.get(position).getPositiveVotes();
        final int iDislikes = list.get(position).getNegativeVotes();

        holder.btnPositive.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final boolean[] voted = {false};
                GetUserVotes mApiGetUserVotes;
                mApiGetUserVotes = ApiUtils.getAPIServiceUserVotes();
                mApiGetUserVotes.getVotes(email, url).enqueue(new Callback<ResultVotes>() {
                    @Override
                    public void onResponse(Call<ResultVotes> call, Response<ResultVotes> response) {
                        if(response.body().getSuccess()==1){
                            voted[0] = true;
                        }else{ voted[0] = false; }
                        if(!voted[0]){
                            //this is not working
                            holder.textViewDislike.setText(String.valueOf(x));
                        } else {
                            //do not update TextView
                        }
                    }

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

                    }
                });
            }
        });
    }

如何根据 Retrofit 响应在单击按钮后更新 TextView 值？

听说有个东西叫'Callback hell'，请问是什么东西，如何有效避免？

Answer 1

您不需要任何全局变量和回调。

刚刚在您的适配器中声明了一个 public 方法，它只更新您的适配器列表。您只需要更新项目的位置。

更新点赞数：

public void updateLikes(int pos){
   int iLikes = list.get(position).getPositiveVotes();
   iLikes++;
   list.get(position).setPositiveVotes(iLikes);
   notifyDataSetChanged();  // very important 

}

更新不喜欢：

public void updateDislikes(int pos){
   int iDislikes = list.get(position).getNegativeVotes();
   iDislikes ++;
   list.get(position).setNegativeVotes(iDislikes);
   notifyDataSetChanged();  // very important 

}

在您的改造或 Aysn 成功调用中，只需调用这些方法：

adapter.updateLikes(position) or adapter.updateDislikes(position)

用户交互后，如何根据 RecyclerView 适配器内服务器的响应更新 TextView？

How to update TextView based on response from server inside RecyclerView adapter after user interaction?

android

android-asynctask

android-studio

retrofit

android-recyclerview