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從適配器（asyncTask）更新片段的textview

[英]Update textview of fragment from Adapter (asyncTask)

 原文  2019-07-21 06:33:22  9   1    java/ android

問題描述

將文本設置為Textview有點麻煩，請檢查以下情況

因此，我有一個片段，片段中有產品名稱，價格和兩個RecyclerView （1個肖像，1個水平），然后在項目上單擊水平RecyclerView，它將嘗試獲取該特定項目的價格，並根據服務器的響應想要將該值設置為fragment的價格TextView ，但是當我顯式更新值時它返回空指針，因此我嘗試了所有下面的代碼，這些代碼都不對我有用。

  1. 在片段中創建用於設置文本的方法，然后從AsyncTask調用該方法（問題：未加載UI，這就是拋出空指針的原因）

  2. 使用Layooutinfleter

。 

protected void onPostExecute(String s) {
        super.onPostExecute(s);
        LayoutInflater inflater = (LayoutInflater) this.context.getSystemService( Context.LAYOUT_INFLATER_SERVICE );
        View view = inflater.inflate( R.layout.fragment_product, null );
        TextView tv = view.findViewById(R.id.productPricePopUp);
        tv.setText(s);
        System.out.println("Rohit " + tv.getText());
    }

我不知道何時設置文本可以正常工作，並且它顯示我設置的文本，但不更新TextView。

是否有將文本設置為TextView的解決方案？ 請幫助我找到解決方案。

水平RecyclerView位於人像RecyclerView（嵌套）中

Product.java（片段） 

public class Product extends SuperBottomSheetFragment {

public TextView name,des,price;
private OnFragmentInteractionListener mListener;
public int id = 0;
public Context context;
public String server_response = null;
public int ArrayID = 0;
public RecyclerView variationRecycler;
public List<variationModel> data = new ArrayList<>();
public variationAdapter adapter;

@Override
public View onCreateView(@NotNull LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    super.onCreateView(inflater, container, savedInstanceState);

    View view1 = inflater.inflate(R.layout.fragment_product, container, false);
    final MainActivity activity;
    activity = (MainActivity)getActivity();
    assert activity != null;
    server_response = activity.server_response;

    name = view1.findViewById(R.id.productNamePopUp);
    des = view1.findViewById(R.id.productDesPopUp);
    price = view1.findViewById(R.id.productPricePopUp);

    variationRecycler = view1.findViewById(R.id.variationRecycler);
    variationRecycler.setNestedScrollingEnabled(true);
    variationRecycler.setLayoutManager(new LinearLayoutManager(view1.getContext().getApplicationContext()));
    variationRecycler.setHasFixedSize(true);
    variationRecycler.setItemAnimator(new DefaultItemAnimator());

    ArrayID = this.getArguments().getInt("id");

    new ExecuteOnBack(context).execute();

    return view1;
}



class ExecuteOnBack extends AsyncTask<Void,Void,Void>{

    String url = null;
    public Context context;
    public ProgressDialog p;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        p = new ProgressDialog(context);
        p.setMessage("Please Wait...");
        p.setCancelable(false);
        p.show();
    }

    public ExecuteOnBack(Context context){
        this.context = context;
    }

    @Override
    protected Void doInBackground(Void... voids) {


        try {
            JSONArray array = new JSONArray(server_response);
            JSONObject object1 = array.getJSONObject(ArrayID);

            name.setText(object1.getString("name"));
            des.setText(object1.getString("short_description"));
            price.setText("Rs." + object1.getString("price"));

            System.out.println("Rohit" + object1.getJSONArray("attributes").getJSONObject(0).getJSONArray("options"));


            for(int k=0;k<object1.getJSONArray("attributes").length();k++){

                ArrayList<optionModel> listdata = new ArrayList<optionModel>();
                JSONArray jArray = object1.getJSONArray("attributes").getJSONObject(k).getJSONArray("options");
                //JSONArray IDArray = object1.getJSONArray("attributes").getJSONObject(k).getJSONArray("ids");
                if (jArray != null) {
                    for (int i=0;i<jArray.length();i++){
                        listdata.add(new optionModel(jArray.getString(i),174));
                    }
                }
                data.add(new variationModel(object1.getJSONArray("attributes").getJSONObject(k).getString("name"),object1.getJSONArray("attributes").getJSONObject(k).getInt("id"),listdata));
            }

            System.out.println("Rohit" + data.get(0).getName());
            adapter = new variationAdapter(data);
            variationRecycler.setAdapter(adapter);

        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
        p.dismiss();
    }
}
}

variantAdapter.java（Portrait Recyclerview） 

    class variationHolder extends RecyclerView.ViewHolder{

    public TextView name;
    public TextView id;
    public ArrayList<String> array = new ArrayList<>();
    public RecyclerView horizontal_variation;

    public variationHolder(@NonNull View itemView) {
        super(itemView);
        name = itemView.findViewById(R.id.variationNameFirst);
        horizontal_variation = itemView.findViewById(R.id.horizontal_variation);
        horizontal_variation.setLayoutManager(new LinearLayoutManager(itemView.getContext(), LinearLayout.HORIZONTAL,false));
        horizontal_variation.setHasFixedSize(true);
        horizontal_variation.setItemAnimator(new DefaultItemAnimator());
       // id = itemView.findViewById(R.id.variationId);
    }
    }
    public class variationAdapter extends RecyclerView.Adapter<variationHolder> {

    public List<variationModel> ListOf;

    public variationAdapter(List<variationModel> listOf) {
        ListOf = listOf;
    }

    @NonNull
    @Override
    public variationHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.portrait_variation, parent, false);
        return new variationHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull variationHolder holder, int position) {
        holder.name.setText(ListOf.get(position).getName());

        horizontalAdapter adapter = new horizontalAdapter(this.ListOf.get(position).getData());
        holder.horizontal_variation.setAdapter(adapter);

        System.out.println("Rohit" + ListOf.get(position).getName());
    }

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

horizo​​ntalAdapter.java（水平適配器） 

class horizontalHolder extends RecyclerView.ViewHolder{

public TextView name,price;
public MaterialCardView variationCard;

public horizontalHolder(@NonNull View itemView) {
    super(itemView);
    name = itemView.findViewById(R.id.variationName);
    variationCard = itemView.findViewById(R.id.variationCard);
    price = itemView.findViewById(R.id.productPricePopUp);
}

static class ExecuteBack extends AsyncTask<String,String,String>{

    String server_response;
    Context context;
    View v;

    public ExecuteBack(Context context,View v) {
        this.context = context;
        this.v = v;
    }

    @Override
    protected String doInBackground(String... url1) {

        URL url;
        HttpURLConnection urlConnection = null;
        try {
            url = new URL(url1[0]);

            urlConnection = (HttpURLConnection) url
                    .openConnection();

            int responseCode = urlConnection.getResponseCode();

            if(responseCode == HttpURLConnection.HTTP_OK){
                server_response = readStream(urlConnection.getInputStream());

                final JSONObject arr = new JSONObject(server_response);
                return arr.getString("price");
            }


        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (urlConnection != null) {
                urlConnection.disconnect();
            }
        }
        return null;
    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        LayoutInflater inflater = (LayoutInflater) this.context.getSystemService( Context.LAYOUT_INFLATER_SERVICE );
        View view = inflater.inflate( R.layout.fragment_product, null );
        TextView tv = view.findViewById(R.id.productPricePopUp);
        tv.setText(s);
        System.out.println("Rohit " + tv.getText());
    }


    private String readStream(InputStream in) {
        BufferedReader reader = null;
        StringBuffer response = new StringBuffer();
        try {
            reader = new BufferedReader(new InputStreamReader(in));
            String line = "";
            while ((line = reader.readLine()) != null) {
                response.append(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return response.toString();
    }
}

}

public class horizontalAdapter extends RecyclerView.Adapter<horizontalHolder> {

private ArrayList<optionModel> ListOf;
public int temp;

horizontalAdapter(ArrayList<optionModel> listOf) {
    ListOf = listOf;
}

@NonNull
@Override
public horizontalHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.variation_recycler, parent, false);
    return new horizontalHolder(view);
}

@Override
public void onBindViewHolder(@NonNull final horizontalHolder holder, final int position) {
    holder.name.setText(this.ListOf.get(position).getName());
    holder.name.setTag(this.ListOf.get(position).getId());

    if(temp ==position){
        holder.variationCard.setCardBackgroundColor(Color.parseColor("#515C6F"));
        holder.name.setTextColor(Color.parseColor("#FFFFFF"));
    }else{
        holder.variationCard.setCardBackgroundColor(Color.parseColor("#FFFFFF"));
        holder.name.setTextColor(Color.parseColor("#515C6F"));
    }

    holder.variationCard.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
        temp = position;
        new horizontalHolder.ExecuteBack(holder.itemView.getContext(),holder.itemView).execute("url");
        notifyDataSetChanged();
        }
    });

}

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

這是用戶界面的圖片

在此處輸入圖片說明

1 個解決方案

解決方案1
 2 已采納  2019-07-21 08:03:58

我相信您要更新的TextView在Fragment布局中。

假設那樣，我建議創建一個說UpdateTextCallback的接口 

public interface UpdateTextCallback {
  public void updateText(String text);  
}

將其實現為存在TextView Fragment類。 

public class Product extends SuperBottomSheetFragment, UpdateTextCallback {
 ...
 ..
 .
class ExecuteOnBack extends AsyncTask<Void,Void,Void>{
 ..
 .

    @Override
    protected Void doInBackground(Void... voids) {
     ...
     ..
     .
     adapter = new variationAdapter(data, Product.this);
            variationRecycler.setAdapter(adapter);
     ...
     ..
     .
  }
 }
 ...
 .. 
 . 
  public void updateText(String text) {
   TextView tv = findViewById(R.id.productPricePopUp);
   tv.setText(s);
   System.out.println("Rohit " + tv.getText());
  }

}

像這樣修改variantAdapter類的構造函數 

public class variationAdapter extends RecyclerView.Adapter<variationHolder> {

    public List<variationModel> ListOf;
    private UpdateTextCallback  updateTextCallback ;

    public variationAdapter(List<variationModel> listOf, UpdateTextCallback  updateTextCallback) {
        ListOf = listOf;
        this.updateTextCallback = updateTextCallback; 
    }
    ...
    ..
    .

    @Override
    public void onBindViewHolder(@NonNull variationHolder holder, int position) {
        holder.name.setText(ListOf.get(position).getName());

        horizontalAdapter adapter = new horizontalAdapter(this.ListOf.get(position).getData(), updateTextCallback);
        holder.horizontal_variation.setAdapter(adapter);

        System.out.println("Rohit" + ListOf.get(position).getName());
    }
    ...
    ..
    .
}

修改horizo​​ntalAdapter類構造函數並像這樣更新文本 

...
..
.
@Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        updateTextCallback.updateText(s);
    }
...
..
.




public class horizontalAdapter extends RecyclerView.Adapter<horizontalHolder> {

  private ArrayList<optionModel> ListOf;
  public int temp;
  private UpdateTextCallback  updateTextCallback ;
  horizontalAdapter(ArrayList<optionModel> listOf, UpdateTextCallback  updateTextCallback) {
    ListOf = listOf;
    this.updateTextCallback = updateTextCallback;
  }
  ...
  ..
  .
}

即使TextView不在Fragment布局中，我也希望您對如何從另一個類更新文本有個好主意。

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