Question

我有这个AsyncTask，当isOnline（）从HTTPost请求的数据加载listview时...如果它不在线，那么它从本地SQLite数据库加载..

我的AsyncTask获取数据（在线 - >来自在线数据库，离线 - >来自我的SQLite数据库）

class ObtenirAmics extends AsyncTask< String, ArrayList<Amic> , ArrayList<Amic> >{
        String data = null;

        protected void onPreExecute() {
            refresh_amics.setVisibility(View.VISIBLE);
            separator_refresh_amics.setVisibility(View.VISIBLE);
            progress_amics.setVisibility(View.VISIBLE);

            separator_amics.setVisibility(View.GONE);
            tv_amics.setVisibility(View.GONE);
            tv_amics.setText("FRIENDS");

            scrollview_amics.scrollTo(0, 0);

            BD=new AmicsSQLiteHelper(getActivity());
            BD.open();


            if(isOnline()){   

            BD.removeTotsAmics();    // If is Online, remove all the friends from 
                                       SQLite Database..
                                         and later it add all the friends another time.     
            }
        }

        protected ArrayList<Amic> doInBackground(String... params) {
            ArrayList<Amic> amics =new ArrayList<Amic>(); 
            if(isOnline()){
            String data;
            SharedPreferences dades_login = getActivity().getSharedPreferences("perfil",
                    getActivity().MODE_PRIVATE);
            String id = dades_login.getString("id", "");

            List<NameValuePair> parametres = new ArrayList<NameValuePair>();
            parametres.add(new BasicNameValuePair("id", id));
            try {
                DefaultHttpClient client = new DefaultHttpClient();
                HttpPost request = new HttpPost(url_obtenir_amics);
                request.setEntity(new UrlEncodedFormEntity(parametres));
                HttpResponse response = client.execute(request);
                HttpEntity entity = response.getEntity();
                data = EntityUtils.toString(entity);
                Log.e("AMICS OBTINGUTS", data);

                try {

                    JSONArray json = new JSONArray(data);

                    for (int i = 0; i < json.length(); i++) {
                        JSONObject obj = json.getJSONObject(i);
                        String nom = obj.getString("nombre");
                        Log.e("PERSONA TROBADA:", nom);

                        addAndSet_Amics(nom); // Its a function that calls a runnable
                                                                     to add to arraylist and setadapter
                    }


                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            } catch (ClientProtocolException e) {
                Log.d("HTTPCLIENT", e.getLocalizedMessage());
            } catch (IOException e) {
                Log.d("HTTPCLIENT", e.getLocalizedMessage());
            }
            }
            else{
                amics = BD.getAllElements(); // HERE IS THE FUNCION THAT GETS 
                                                    ALL THE DATA FROM SQLite
                adapter.notifyDataSetChanged();
            }

            return amics;

        }

       protected void onPostExecute(ArrayList<Amic> amics) {

           refresh_amics.setVisibility(View.GONE);
        separator_refresh_amics.setVisibility(View.GONE);
        progress_amics.setVisibility(View.GONE);

           if(amics.size()>0){
                tv_amics.setVisibility(View.VISIBLE);
                separator_amics.setVisibility(View.VISIBLE);
                }
                    listView_Amics.setAdapter(adapter);
                    Utility.setListViewHeightBasedOnChildren(listView_Amics,scrollview_amics);

            }

        }

在我的Helper SQLite类中，我有一个函数返回包含我数据库所有行的列表..（logcat显示所有朋友，但在listview中没有显示任何内容）

public ArrayList<Amic> GetAllValues()
    {
        ArrayList<Amic> list = new ArrayList<Amic>();
        Cursor cursor = myDataBase.query(DATABASE_TABLE, cols, null, null, null, null, null);
        if (cursor.moveToFirst())
        {
            do
            {
                list.add(new Amic(cursor.getString(0)));
                Log.e("Afegint",cursor.getString(0));
            }
            while (cursor.moveToNext());
        }
        if (cursor != null && !cursor.isClosed()) 
        {
            cursor.close();
        }

        return list;
    }

Answer 1

在数据切换时，您还必须更新适配器数据。

并在更新后，您需要调用adapter.notifyDataSetChanged（）;.

以下是一个例子：

在适配器中创建一个方法，如下所示：

public void setData(ArrayList<object> newData) {
this.data = newData;
 }

然后在你的Acitivty中添加如下内容：

if(items!=null && items.size()>0) {

  // First time calling adapter
 if(adapter==null){
 adapter = new FeedAdapter(getActivity(), items);
       if(adapter!=null)
         listView.setAdapter(adapter); 
 }
 // Updating your adapter with new data.
 else {
 adapter.setData(yourArrayList);
 adapter.notifyDataSetChanged();
 }

将数据从SQLite加载到我的ListView

1 个答案: