Question

谜语我，蝙蝠侠。我的代码部分是

public class SurveyDbModel
{
    // name of connection string for database that 
    private static readonly string _ConnStrName = "LocalDb";

    private SqlConnection Conn; 

    public SurveyModelDb ( )
    {
        this.Conn = new SqlConnection(ConfigurationManager.ConnectionStrings[SurveyDbModel._ConnStrName].ConnectionString);
    }

}

并且Visual Studio错误指向SurveyModelDb。我不知道我做错了什么因为我的synatx似乎匹配the example on MSDN，

public class Taxi
{
    public bool isInitialized;
    public Taxi()
    {
        isInitialized = true;
    }
}

Answer 1

您的构造函数方法名称需要与您的类名匹配，否则编译器会认为它是常规方法，因此需要返回类型。

例如

public class SurveyDbModel
{
    // name of connection string for database that 
    private static readonly string _ConnStrName = "LocalDb";

    private SqlConnection Conn; 

    public SurveyDbModel ( )
    {
        this.Conn = new SqlConnection(ConfigurationManager.ConnectionStrings[SurveyDbModel._ConnStrName].ConnectionString);
    }

}

Answer 2

构造函数名称SurveyModelDb与类名SurveyDbModel ..

不匹配

Answer 3

此public class IndicesFragment extends android.support.v4.app.Fragment implements SwipeRefreshLayout.OnRefreshListener { public static String imagepath = null; public static FetchAllData myTask; static ArrayList<EquityDetails> catListDao = new ArrayList<EquityDetails>(); static ArrayList<EquityDetails> catListDao1 = new ArrayList<EquityDetails>(); static int count = 0; static int count1 = 0; ListView list; ImageView progressBar; View view; Activity act; AdvisorsAdapter adapter; TextView empty_text; AnimatorSet set; JSONArray jsonArray; SwipeRefreshLayout swipeRefreshLayout; private boolean isViewShown = false; public static IndicesFragment newInstance() { return new IndicesFragment(); } @Override public void setUserVisibleHint(boolean isVisibleToUser) { super.setUserVisibleHint(isVisibleToUser); if (isVisibleToUser) { isViewShown = true; if (adapter != null) { adapter.filter(""); } } else { isViewShown = false; } } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { view = inflater.inflate(R.layout.equity_activity, container, false); act = this.getActivity(); Constants.check_fragment_visible = 1; count++; setHasOptionsMenu(true); list = (ListView) view.findViewById(R.id.list_equity); empty_text = (TextView) view.findViewById(R.id.empty); swipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipe_refresh_layout); progressBar = (ImageView) view.findViewById(R.id.progressBar); set = (AnimatorSet) AnimatorInflater.loadAnimator(getActivity(), R.animator.fadein); set.setTarget(progressBar); progressBar.setVisibility(View.GONE); if (Utils.isNetworkAvailable(getActivity())) { if (catListDao.size() > 0) { adapter = new AdvisorsAdapter(act, R.layout.custom_equity, catListDao, 0); list.setAdapter(adapter); } else { if (!isViewShown) { new FetchAllData(getActivity(), 3).execute(); } } } else { CustomToast toast = new CustomToast(getActivity(), "There is no internet connection!"); } swipeRefreshLayout.setOnRefreshListener(this); return view; } public void onActivityCreated(Bundle savedInstanceState1) { super.onActivityCreated(savedInstanceState1); } @Override public void onResume() { super.onResume(); Constants.check_fragment_visible = 1; if (Constants.check_reload) { if (Utils.isNetworkAvailable(getActivity())) { new FetchAllData(getActivity(), 3).execute(); } else { CustomToast toast = new CustomToast(getActivity(), "There is no internet connection!"); } } if (adapter != null) adapter.notifyDataSetChanged(); } @Override public void onRefresh() { if (Utils.isNetworkAvailable(getActivity())) { new FetchAllData(getActivity(), 3).execute(); } else { CustomToast toast = new CustomToast(getActivity(), "There is no internet connection!"); } } public void doChange(String queryText) { if (queryText != null) { if (adapter != null) adapter.filter(queryText); } } public void parseJSON(String result) { if (result != null) { JSONObject jsonObject; try { catListDao = new ArrayList<EquityDetails>(); jsonObject = new JSONObject(result); jsonArray = jsonObject.getJSONArray("list"); Log.d("Length ", "" + jsonArray.length()); for (int i = 0; i < jsonArray.length(); i++) { EquityDetails allDirectory = new EquityDetails(); allDirectory.setEntry_value(jsonArray.getJSONObject(i).getString("entry")); String value1 = jsonArray.getJSONObject(i).getString("entry"); String value2 = jsonArray.getJSONObject(i).getString("tgt_1"); allDirectory.setSerial_value(jsonArray.getJSONObject(i).getString("sl")); allDirectory.setTg_value1(jsonArray.getJSONObject(i).getString("tgt_1")); allDirectory.setTg_value2(jsonArray.getJSONObject(i).getString("tgt_2")); allDirectory.setPosted_by(jsonArray.getJSONObject(i).getString("posted_by")); allDirectory.setMainTitle_value(jsonArray.getJSONObject(i).getString("script")); allDirectory.setMain_subTitle_value(jsonArray.getJSONObject(i).getString("exchange")); allDirectory.setRating_value(jsonArray.getJSONObject(i).getString("rating")); allDirectory.setReview_value(jsonArray.getJSONObject(i).getString("review")); imagepath = jsonArray.getJSONObject(i).getString("advisor_image"); Log.d("Comminh Image ", "" + jsonArray.getJSONObject(i).getString("advisor_image")); allDirectory.setImage1(jsonArray.getJSONObject(i).getString("advisor_image")); allDirectory.setImage2(jsonArray.getJSONObject(i).getString("script_image")); allDirectory.setBuy(jsonArray.getJSONObject(i).getString("buy_sentiment")); allDirectory.setSell(jsonArray.getJSONObject(i).getString("sell_sentiment")); allDirectory.setRecommend(jsonArray.getJSONObject(i).getString("recommendation")); allDirectory.setPosted_date(jsonArray.getJSONObject(i).getString("posted_date")); allDirectory.setCall_id(jsonArray.getJSONObject(i).getString("call_id")); allDirectory.setExpiry_date(jsonArray.getJSONObject(i).getString("expiry_date")); allDirectory.setBroker_name(jsonArray.getJSONObject(i).getString("name")); allDirectory.setCall_detail(jsonArray.getJSONObject(i).getString("detail")); allDirectory.setProgress_indicator(0); catListDao.add(allDirectory); } catListDao1 = catListDao; adapter = new AdvisorsAdapter(act, R.layout.custom_equity, catListDao, 0); } catch (JSONException e) { e.printStackTrace(); } } } public class FetchAllData extends AsyncTask<Void, Void, String> { ProgressDialog pDialog; int typeId; private Context cont; public FetchAllData(Context con, int typeId) { // TODO Auto-generated constructor stub this.cont = con; this.typeId = typeId; Log.d("Constructor Called", "yes"); } @Override protected void onPreExecute() { // TODO Auto-generated method stub super.onPreExecute(); if (!swipeRefreshLayout.isRefreshing()) { if (progressBar != null) { progressBar.setVisibility(View.VISIBLE); set.start(); } } } @Override protected String doInBackground(Void... params) { // TODO Auto-generated method stub return getString(); } private String getString() { // TODO Auto-generated method stub URL obj = null; HttpURLConnection con = null; try { obj = new URL(Constants.AppBaseUrl + "/call_listing/" + typeId); String userPassword = "rickmams" + ":" + "advisor11"; String header = "Basic " + new String(android.util.Base64.encode(userPassword.getBytes(), android.util.Base64.NO_WRAP)); con = (HttpURLConnection) obj.openConnection(); con.addRequestProperty("Authorization", header); con.setRequestProperty("Content-type", "application/x-www-form-urlencoded"); con.setRequestMethod("POST"); // For POST only - BEGIN con.setDoOutput(true); OutputStream os = con.getOutputStream(); os.flush(); os.close(); // For POST only - END int responseCode = con.getResponseCode(); if (responseCode == HttpURLConnection.HTTP_OK) { //success BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream())); String inputLine; StringBuilder response = new StringBuilder(); while ((inputLine = in.readLine()) != null) { response.append(inputLine); } in.close(); Log.i("TAG", response.toString()); parseJSON(response.toString()); return response.toString(); } else { Log.i("TAG", "POST request did not work."); } } catch (IOException e) { e.printStackTrace(); } finally { if (con != null) { con.disconnect(); } } return null; } @Override protected void onPostExecute(String result) { // TODO Auto-generated method stub super.onPostExecute(result); if (getActivity() == null) return; if (swipeRefreshLayout.isRefreshing()) { swipeRefreshLayout.setRefreshing(false); } if (result != null) { if (progressBar != null) { list.setAdapter(adapter); //pDialog.dismiss(); if (progressBar != null) { set.end(); if (progressBar.getVisibility() == View.VISIBLE) progressBar.setVisibility(View.GONE); } if (jsonArray.length() != 0) { empty_text.setVisibility(View.GONE); } else empty_text.setVisibility(View.VISIBLE); } } } } }与SurveyDbModel不同。构造函数应与类的名称相同。 SurveyModelDb是一种您尚未提供返回类型的方法。

Answer 4

构造函数名称应与类名匹配。这里的类名是'SurveyDbModel'，但是ctor是'SurveyModelDb'。

将SurveyModelDb更改为public SurveyModelDb(){}

Answer 5

显然公开的SurveyModelDb（）不是 SurveyDbModel 的.ctor。

“类必须在类构造函数上具有返回类型”

5 个答案: