Question

这是我的主要类，我设置适配器并调用notifydatasetchanged（）方法，目的是在listview中显示用户的历史记录并在数据更改时刷新，但是如前所述出现错误

public class HistoryActivity extends AppCompatActivity {

// Log tag
private static final String TAG = HistoryActivity.class.getSimpleName();
private static final String url ="http://192.168.0.102/android_login_api/historyfetch.php";
private ProgressDialog pDialog;
private List<HistoryItems> historyList = new ArrayList<HistoryItems>();
private ListView listView;
private CustomListAdapter adapter;
private SQLiteHandler db;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_history);

    listView = (ListView) findViewById(R.id.list);
    adapter = new CustomListAdapter(this, historyList);
    listView.setAdapter(adapter);

    pDialog = new ProgressDialog(this);
    // Showing progress dialog before making http request
    pDialog.setMessage("Loading...");
    pDialog.show();

    db = new SQLiteHandler(getApplicationContext());

    HashMap<String, String> user = db.getUserDetails();
    String user_email = user.get("email");
    gethistory(user_email);
}

private void gethistory(final String email)
{
    StringRequest stringRequest= new StringRequest(Request.Method.POST, url, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            Log.d(TAG,response.toString());
            hideDialog();
            try {
                JSONArray jsonArray = new JSONArray(response);
                for(int i=0;i<response.length();i++)
                {
                    JSONObject obj = jsonArray.getJSONObject(i);
                    HistoryItems historyItems = new HistoryItems();
                    historyItems.setName(obj.getString("user_email"));
                    historyItems.setLat_from(obj.getDouble("latitude_from"));
                    historyItems.setLon_from(obj.getDouble("longitude_from"));
                    historyItems.setLat_to(obj.getDouble("latitude_to"));
                    historyItems.setLon_to(obj.getDouble("longitude"));
                    historyItems.setDate(obj.getString("created_at"));

                    historyList.add(historyItems);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
        adapter;
    })

    {
        protected Map<String,String>getParams(){
            Map<String, String> params=new HashMap<>();
            params.put("user_email",email);
            return params;
        }
    };
    AppController.getInstance().addToRequestQueue(stringRequest);
}
private void showDialog() {
    if (!pDialog.isShowing())
        pDialog.show();
}

private void hideDialog() {
    if (pDialog.isShowing())
        pDialog.dismiss();
}

}

这是我的自定义适配器： -

public class CustomListAdapter extends BaseAdapter {

private Activity activity;
private LayoutInflater inflater;
private List<HistoryItems> historyItems;


public CustomListAdapter(Activity activity, List<HistoryItems> historyItems) {
    this.activity = activity;
    this.historyItems = historyItems;
}

@Override
public int getCount() {
    return historyItems.size();
}

@Override
public Object getItem(int location) {
    return historyItems.get(location);
}

@Override
public long getItemId(int position) {
    return position;
}

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

    if (inflater == null)
        inflater = (LayoutInflater) activity
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    if (convertView == null)
        convertView = inflater.inflate(R.layout.list_row, null);


    TextView user_email = (TextView) convertView.findViewById(R.id.tv_user_email);
    TextView lat_from = (TextView) convertView.findViewById(R.id.tv_lat_from);
    TextView lon_from = (TextView) convertView.findViewById(R.id.tv_lon_from);
    TextView lat_to = (TextView) convertView.findViewById(R.id.tv_lat_to);
    TextView lon_to = (TextView) convertView.findViewById(R.id.tv_lon_to);
    TextView date = (TextView) convertView.findViewById(R.id.tv_date);

    // getting billionaires data for the row
    HistoryItems m = historyItems.get(position);


    // name
    user_email.setText(m.getUser_email());

    //
    lat_from.setText(String.valueOf(m.getLat_from()));


    lon_from.setText(String.valueOf(m.getLon_from()));

    lat_to.setText(String.valueOf(m.getLat_to()));

    lon_to.setText(String.valueOf(m.getLon_to()));

    date.setText(String.valueOf(m.getDate()));


    return convertView;
}

}

我没有得到我犯错误的地方任何帮助都会有所帮助....

Answer 1

嘿，我没有在你的代码中看到任何notifydatasetchanged（）我只看到适配器; 解决方案==＆gt; adapter.notifydatasetchanged（）;应该在捕获后不在方法之外

Answer 2

你必须为你的适配器提供notifyDataSetChanged（）......

像这样

    for(int i=0;i<response.length();i++)
       {
          JSONObject obj = jsonArray.getJSONObject(i);
          HistoryItems historyItems = new HistoryItems();
          .
          .
          .
          .

          historyList.add(historyItems);
        }
adapter.notifyDataSetChanged();

希望，它会帮助你:)。

Answer 3

每次添加新项目适配器都会在列表视图中添加新项目。

for(int i=0;i<response.length();i++)
            {
                JSONObject obj = jsonArray.getJSONObject(i);
                HistoryItems historyItems = new HistoryItems();
                historyItems.setName(obj.getString("user_email"));
                historyItems.setLat_from(obj.getDouble("latitude_from"));
                historyItems.setLon_from(obj.getDouble("longitude_from"));
                historyItems.setLat_to(obj.getDouble("latitude_to"));
                historyItems.setLon_to(obj.getDouble("longitude"));
                historyItems.setDate(obj.getString("created_at"));

                historyList.add(historyItems);
                adapter.notifyDataSetChanged();

            }

在listview中，notifyDataSetChanged（）方法有错误

3 个答案: