Question

我面临的问题是来自服务器的JSON数据保存在ArrayList中，当在自定义适配器中调用ArrayList时返回null。自定义适配器用于列出android中微调器中的数据。

public class PhotoCommnFragment extends android.support.v4.app.Fragment {
    EditText rechargeMobileNumber,rechargeAmount;
    Spinner selectMenu;
    int flags[] = {R.drawable.airteltv, R.drawable.aircel, R.drawable.dishtv, R.drawable.sundirect, R.drawable.tatasky, R.drawable.videocon};
    List<SpinnerMenu> selectedNetwork = new ArrayList<>();
    public PhotoCommnFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_tab_mobile, container, false);
        mobileRecahrgeHistory();
        rechargeMobileNumber = (EditText)rootView.findViewById(R.id.recharge_mobile_number);
        rechargeAmount = (EditText)rootView.findViewById(R.id.recharge_amount);
        selectMenu = (Spinner)rootView.findViewById(R.id.selectNetwork);
        settingSpinnerDropDown();
        return rootView;
    }

    public void mobileRecahrgeHistory(){
        Ion.with(this)
                .load("http://192.168.1.105/TotalRecharge/?api=ol&uid=1")
                .asJsonObject().withResponse()
                .setCallback(new FutureCallback<Response<JsonObject>>() {
                    @Override
                    public void onCompleted(Exception e, Response<JsonObject> result) {
                        JSONObject json = null;

                        try {
                            json = new JSONObject(result.getResult().toString());
                        } catch (JSONException e1) {
                            e1.printStackTrace();
                        }
                        // Create the root JSONObject from the JSON string.
                        JSONObject jsonRootObject = null;
                        jsonRootObject = json.optJSONObject("DS");

                        //Get the instance of JSONArray that contains JSONObjects
                        JSONArray jsonArray = jsonRootObject.optJSONArray("LST");

                        //Iterate the jsonArray and print the info of JSONObjects
                        for(int i=0; i < jsonArray.length(); i++){
                            JSONObject jsonObject = null;
                            try {
                                jsonObject = jsonArray.getJSONObject(i);
                            } catch (JSONException e1) {
                                e1.printStackTrace();
                            }
                            String iph = null;

                            String oid = jsonObject.optString("OID").toString();
                            String ocd = jsonObject.optString("OCD").toString();
                            String opd = jsonObject.optString("OPE").toString();
                            String mil = jsonObject.optString("MIL").toString();
                            String mxl = jsonObject.optString("MXL").toString();
                            try {
                                 iph = jsonObject.getString("IPH").toString();
                            } catch (JSONException e1) {
                                e1.printStackTrace();
                            }

                            String urldisplay = "http://192.168.1.105/TotalRecharge/"+iph;
                            Bitmap mIcon11 = null;
                            try {
                                InputStream in = new java.net.URL(urldisplay).openStream();
                                mIcon11 = BitmapFactory.decodeStream(in);
                            } catch (Exception e3) {
                                e3.printStackTrace();
                            }
                            SpinnerMenu spinnerData = new SpinnerMenu();
                            spinnerData.setOid(oid);
                            spinnerData.setOcd(ocd);
                            spinnerData.setOpd(opd);
                            spinnerData.setMil(mil);
                            spinnerData.setMix(mxl);
                            spinnerData.setImage(mIcon11);

                            selectedNetwork.add(spinnerData);

                        }

                    }

                });
    }


    public void settingSpinnerDropDown(){
        Fragment_DTH_Main_Spinner_Adapter customAdapter=new Fragment_DTH_Main_Spinner_Adapter(getActivity(),R.layout.fragment_dth_main_spinner_items,R.id.serviceName,selectedNetwork);
        selectMenu.setAdapter(customAdapter);
    }

在上面的代码中，来自服务器的json数据保存在ArrayList中的selectedNetwork.add(spinnerData);中，但是当我在以下内容中调用已保存的arraylist数据时：

Fragment_DTH_Main_Spinner_Adapter customAdapter=new Fragment_DTH_Main_Spinner_Adapter(getActivity(),R.layout.fragment_dth_main_spinner_items,R.id.serviceName,selectedNetwork);

当在自定义适配器中传递数据时，ArrayList返回null。

当我通过调试检查时，JSON数据保存在ArrayList中，但是当它在适配器中调用时返回null。

我不知道这有什么错误。请帮我解决这个问题。 `

以下代码是在自定义adatapter中设置数据

 public class Fragment_DTH_Main_Spinner_Adapter extends ArrayAdapter<SpinnerMenu> {
        Context context;
    int flags[];
    List<SpinnerMenu> countryNames;
    LayoutInflater inflter;

    public Fragment_DTH_Main_Spinner_Adapter(FragmentActivity activity, int resouceId, int textviewId, List<SpinnerMenu> data) {


   //     super(activity, R.layout.fragment_dth_main_spinner_items,userstories);
        super(activity,resouceId,textviewId,data);
        this.countryNames = data;
    }

    public class ViewHolder
    {
        TextView names;
        ImageView icon;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        LayoutInflater inflater  = LayoutInflater.from(getContext());
        convertView = inflater.inflate(R.layout.fragment_dth_main_spinner_items, parent, false);
   //     convertView = inflter.inflate(fragment_dth_main_spinner_items, null);
        SpinnerMenu spinnerData = countryNames.get(position);
        ViewHolder viewHolder;
        View result;

        if(convertView == null){
            viewHolder = new ViewHolder();
            viewHolder.icon = (ImageView) convertView.findViewById(R.id.imageView);
             viewHolder.names = (TextView) convertView.findViewById(R.id.serviceName);
            result = convertView;
        }
        else {
            viewHolder = (ViewHolder) convertView.getTag();
            result = convertView;
        }
//        viewHolder.icon.setImageBitmap(spinnerData.getImage());
        viewHolder.names.setText(spinnerData.getOpd());
        return convertView;
    }
}

在上面的代码中查看Holder.name.setText（）;该值返回null。我试过但仍然返回null。我不知道这个方法有什么问题。

Answer 1

不是将项添加到selectedNetwork数组，而是将它们添加到适配器。 e.g。

private Fragment_DTH_Main_Spinner_Adapter customAdapter;

@Override
public View onCreateView(LayoutInflater inflater, 
                         ViewGroup container,
                         Bundle savedInstanceState) {


    ...

    customAdapter = new Fragment_DTH_Main_Spinner_Adapter(getActivity(),
        R.layout.fragment_dth_main_spinner_items,
        R.id.serviceName,
        new ArrayList<SpinnerMenu>() );
}

然后替换：

selectedNetwork.add(spinnerData);

带

customAdapter.add(spinnerData);

Answer 2

这是因为您的mobileRecahrgeHistory()方法正在调用以下代码：

Ion.with(this)
   .load("http://192.168.1.105/TotalRecharge/?api=ol&uid=1")
   .asJsonObject().withResponse()
   .setCallback(new FutureCallback<Response<JsonObject>>() {

     ...
     selectedNetwork.add(spinnerData);
     ...
   }

异步。 settingSpinnerDropDown();完成后，mobileRecahrgeHistory已经完成。

所以你需要告诉适配器它的数据是用notifyDataSetChanged()方法改变的。

保存在arraylist中的数据在自定义适配器中调用arraylist时返回null？

2 个答案: