Android 在AsyncTask类中设置适配器

我有一个扩展片段并调用异步任务类的代码。但我不能设定收养者。我面对错误。我在下面添加了片段和错误代码： 设置适配器时，此错误在此行中：

                    lv.setAdapter(adapter);

下面是扩展片段的完整代码：

    public class AllProductsActivity extends Fragment  {
    private RadioGroup radioGroup;
   private RadioButton radioSexButton;
   private Button btnDisplay;
   ListView  lv;
    private ProgressDialog pDialog;

    // Creating JSON Parser object
    JSONParser jParser = new JSONParser();

    ArrayList<HashMap<String, String>> productsList;

    // url to get all products list
    private static String url_all_products = "http://192.168.1.108/android_connect/get_all_products.php";

    // JSON Node names
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_PRODUCTS = "products";
    private static final String TAG_PID = "pid";
    private static final String TAG_NAME = "name";

    // products JSONArray
    JSONArray products = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.all_products, container, false);


        productsList = new ArrayList<HashMap<String, String>>();
        LoadAllProducts downloadimage = new LoadAllProducts();
        lv = (ListView) rootView.findViewById(R.id.list);

         downloadimage.execute();
        return rootView;


        }

    }

    /**
     * Background Async Task to Load all product by making HTTP Request
     * */
    class LoadAllProducts extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(getActivity());
            pDialog.setMessage("Loading products. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        /**
         * getting All products from url
         * */
        protected String doInBackground(String... args) {
            // Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            // getting JSON string from URL
            JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);

            // Check your log cat for JSON reponse
            Log.d("All Products: ", json.toString());

            try {
                // Checking for SUCCESS TAG
                int success = json.getInt(TAG_SUCCESS);

                if (success == 1) {
                    // products found
                    // Getting Array of Products
                    products = json.getJSONArray(TAG_PRODUCTS);

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

                        // Storing each json item in variable
                        String id = c.getString(TAG_PID);
                        String name = c.getString(TAG_NAME);

                        // creating new HashMap
                        HashMap<String, String> map = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        map.put(TAG_PID, id);
                        map.put(TAG_NAME, name);

                        // adding HashList to ArrayList
                        productsList.add(map);
                    }
                } else {

                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after getting all products
            pDialog.dismiss();

                    /**
                     * Updating parsed JSON data into ListView
                     * */
                    MainCustomList adapter;
                   // lv = (ListView) getView().findViewById(R.id.list);

                    String[] test = new String[] { "1", "2", "3" };

                    adapter = new MainCustomList(getActivity(), test);


                   lv.setAdapter(adapter);

            //   }
           // });

        }







  }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
         lv = (ListView) view.findViewById(R.id.list);}


   }

在这里：

因为

lv

为

null

而导致

NPE

的行

ListView

with

list

位于片段内部，而不是片段容器

Activity

使用片段的getView方法而不是

getActivity

从片段布局访问ListView：

lv = (ListView) getView().findViewById(R.id.list);

或者最好使用片段的

onViewCreated

或

onCreateView

方法初始化视图：

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
     lv = (ListView) view.findViewById(R.id.list);
}

---

我也使用getview，但不使用help。@user5508330:然后使用创建的视图的

onviewCreate

method这行代码是：lv.setAdapter（adapter）；我在ViewCreated上尝试过这个，但没有帮助。谢谢。是的，我的问题是我必须在两个不同的布局中列出具有相同名称的视图。请发布错误日志。第330行代码是什么。此行：lv.setAdapter（adapter）；为什么要投反对票。我确实有问题。您是否在onCreateView中返回了根视图。

lv = (ListView) getView().findViewById(R.id.list);

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
     lv = (ListView) view.findViewById(R.id.list);
}