Question

我在片段中有一个listview。它从Json加载数据。单击列表项后，片段事务开始（替换）。通过按下后退按钮（在新片段中）再次出现列表片段，但问题是：
1：它再次加载Asynctask（我不想要它） 2.它在列表中的前一项上添加新项目。你可以说listview项目中的重复发生。每次单击listview项目abd然后返回到listview片段时，它会将相同的项目添加到列表的末尾。我的代码是这样的：

public class Followed extends Fragment {
public Followed(){}

ArrayList<Country> countryList = new ArrayList<Country>();
Country country;
ListView listView;
JSONParser jsonParser = new JSONParser();
public static String received_id;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
MyCustomAdapter dataAdapter = null;
ProgressDialog pDialog;
int success;

private static String url_all_followed = "http://www.hitel.ir/FarsiPlanet/Followed.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";
private static final String TAG_RATE = "rate";
private static final String TAG_RATINGCOUNT = "ratingcount";
private static final String TAG_SHORT_DESCRIPTION = "short_description";

// products JSONArray
JSONArray products = null;
String Category;
String username;

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

    View rootView = inflater.inflate(R.layout.items_list, container, false);
    loadSavedPreferences();

    listView = (ListView) rootView.findViewById(R.id.listView1);
    listView.setOnItemClickListener(new OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            final String pid = ((TextView) view.findViewById(R.id.pid)).getText().toString();
            Bundle data = new Bundle();
            data.putString(TAG_PID, pid);
            data.putString("TAG_Category", "restaurant");
            Fragment fragment = new Details_Restaurant();
            FragmentManager fm = getFragmentManager();
            fragment.setArguments(data);
            fm.beginTransaction().replace(R.id.frame_container, fragment).addToBackStack("f_02asda").commit();
        }
    });
    new loadMoreListView().execute();

    return rootView;
}

private class MyCustomAdapter extends ArrayAdapter<Country> {

    private ArrayList<Country> countryList;

    public MyCustomAdapter(Context context, int textViewResourceId, 
            ArrayList<Country> countryList) {
        super(context, textViewResourceId, countryList);
        this.countryList = new ArrayList<Country>();
        this.countryList.addAll(countryList);
    }

    private class ViewHolder {
        TextView code;
        TextView name;
        RatingBar rate;
        TextView ratingcount;
        TextView short_description;
    }

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

        ViewHolder holder = null;
        if (convertView == null) {

            LayoutInflater vi = (LayoutInflater)getActivity().getSystemService(
                    Context.LAYOUT_INFLATER_SERVICE);
            convertView = vi.inflate(R.layout.country_info, null);

            holder = new ViewHolder();
            holder.name = (TextView) convertView.findViewById(R.id.name);
            holder.ratingcount = (TextView) convertView.findViewById(R.id.ratingCount);
            holder.short_description = (TextView) convertView.findViewById(R.id.short_description);
            holder.rate = (RatingBar) convertView.findViewById(R.id.ratingBar1);
            holder.code = (TextView) convertView.findViewById(R.id.pid);

            convertView.setTag(holder);

        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        final Country country = countryList.get(position);
        holder.name.setText(country.getName());
        holder.ratingcount.setText(country.getRatingCount());
        holder.short_description.setText(country.getShort_description());
        holder.rate.setRating(country.getRate());
        holder.code.setText(country.getCode());

        return convertView;
    }
}

class loadMoreListView extends AsyncTask<String, String, String> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        pDialog = new ProgressDialog(getActivity());
        pDialog.setMessage("درحال دريافت اطلاعات...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(false);
        pDialog.show(); 
    }

    /**
     * getting All products from url
     * */
    protected String doInBackground(String... args) {

        try {
            // Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("username", "sajad"));

            // getting product details by making HTTP request
            // Note that product details url will use GET request
            JSONObject json = jsonParser.makeHttpRequest(
                    url_all_followed, "GET", params);

            // json success tag
            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);
                    Float rate = (float) c.getInt(TAG_RATE);
                    String ratingcount = c.getString(TAG_RATINGCOUNT);
                    String short_description = c.getString(TAG_SHORT_DESCRIPTION);

                    country = new Country(id,name,rate,ratingcount,short_description,"","");
                    countryList.add(country);

                }
            }
            else{

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

        return null;
    }

    protected void onPostExecute(String file_url) {
        if (success == 0) {
            Toast.makeText(getActivity(), "هیچ موردی یافت نشد!", Toast.LENGTH_SHORT).show();
        }
        pDialog.dismiss();
        dataAdapter = new MyCustomAdapter(getActivity(),
                R.layout.country_info, countryList);
        listView.setAdapter(dataAdapter);
    }
}

public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getActivity().getMenuInflater();
    inflater.inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    return super.onOptionsItemSelected(item);
}
private void loadSavedPreferences() {
    SharedPreferences sharedPreferences = PreferenceManager
            .getDefaultSharedPreferences(getActivity());
    username = sharedPreferences.getString("username", "");
}
}

Answer 1

好的。发现重复问题。我在点击列表项后清除了适配器。

    listView.setOnItemClickListener(new OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            final String pid = ((TextView) view.findViewById(R.id.pid)).getText().toString();
            Bundle data = new Bundle();
            data.putString(TAG_PID, pid);
            data.putString("TAG_Category", "restaurant");
            Fragment fragment = new Details_Restaurant();
            FragmentManager fm = getFragmentManager();
            fragment.setArguments(data);
            fm.beginTransaction().replace(R.id.frame_container, fragment).addToBackStack("f_02asda").commit();
            dataAdapter.clear();
        }
    });

Listadapter在每次asynctask开始后复制listview中的项目

1 个答案: