Question

我使用矩阵光标向光标添加行。

在Create

上的MainActivity中定义列

//In protected void onCreate

String[] columns = new String[] { "dealername", "product","type","description","location","sublocation","address","phone1","phone2","auth","brands","lat","lon"};
cursor= new MatrixCursor(columns);

// -----------------在asyctask doinbackground中

cursor.addRow(new String[] {json.getString("dealername"),json.getString("product"), json.getString("type"),json.getString("description"),json.getString("location"),json.getString("sublocation"),json.getString("address"),json.getString("phone1"),json.getString("phone2"),json.getString("auth"),json.getString("brands"),json.getString("lat"),json.getString("lon")});

当我尝试获取光标中的列数时，应用程序只会崩溃

protected void onPostExecute(Void aVoid) {
    super.onPostExecute(aVoid);
    Toast.makeText(getApplicationContext(), cursor.getCount(),Toast.LENGTH_LONG).show();
}

更新：

 private class getdealerinfo extends AsyncTask<Void,Void,MatrixCursor> {

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

            }


            @Override
            protected  MatrixCursor doInBackground(Void... args) {

                /* Building Parameters */

                List<NameValuePair> params = new ArrayList<NameValuePair>();
                params.add(new BasicNameValuePair("pname",selectedproduct));
                params.add(new BasicNameValuePair("location",selectedlocation));

                /* getting JSON string from URL */
                JSONObject json = jParser.makeHttpRequest(dealers_url, "GET", params);

                try {
                    /* Checking for SUCCESS TAG */
                    int success = json.getInt(TAG_SUCCESS);
                    if (success == 1) {
                        JSONArray JAStuff = json.getJSONArray(TAG_STUFF);

                        /** CHECK THE NUMBER OF RECORDS **/
                        int intStuff = JAStuff.length();
                        //creating array 
                        dealerdetailsarray =new String[intStuff][12];
                        if (intStuff != 0) {
                             String[] str1 = new String[JAStuff.length()]; 
                             for(int i=0;i<JAStuff.length();i++)
                             {
                             json=JAStuff.getJSONObject(i);
                            // startManagingCursor(cursor);
                  //         dealerdetailsarray[0][0]=json.getString("dealername");
                             cursor.addRow(new String[] {json.getString("dealername"),json.getString("product"), json.getString("type"),json.getString("description"),json.getString("location"),json.getString("sublocation"),json.getString("address"),json.getString("phone1"),json.getString("phone2"),json.getString("auth"),json.getString("brands"),json.getString("lat"),json.getString("lon")});

                             } 
                             }
                    }
                } catch (Exception e) {
              Log.e("test",e.toString());
                }
                return cursor; 
            }


            @Override
            protected void onPostExecute(MatrixCursor cursor) {
            //    super.onPostExecute(aVoid);
             try
             {
              Toast.makeText(getApplicationContext(), cursor.getCount(),Toast.LENGTH_LONG).show();
             }
             catch (Exception e) {
                  Log.e("myerror",e.getMessage());
                    } 
       }
        }

    }

Answer 1

您需要将cursor对象从doInBackground()返回到onPostExecute()。将您的AsyncTask课程定义为

class XYZTask extends AsyncTask<Void, Void, MatrixCursor>{

    protected MatrixCursor doInBackground(Void... void) {

         .....
         cursor.addRow(new String[] {json.getString("dealername"),json.getString("product"), json.getString("type"),json.getString("description"),json.getString("location"),json.getString("sublocation"),json.getString("address"),json.getString("phone1"),json.getString("phone2"),json.getString("auth"),json.getString("brands"),json.getString("lat"),json.getString("lon")});
         return cursor;
    }

    protected void onPostExecute(MatrixCursor cursor) {
        Toast.makeText(getApplicationContext(), cursor.getCount(),Toast.LENGTH_LONG).show();
    }


}

并将cursor对象从doInBackground()作为参数返回到onPostExecute()。

修改

像这样定义AsyncTask：

private class getdealerinfo extends AsyncTask<Void,Void,JSONObject> { @Override protected void onPreExecute() { super.onPreExecute(); } @Override protected JSONObject doInBackground(Void... args) { /* Building Parameters */ List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("pname",selectedproduct)); params.add(new BasicNameValuePair("location",selectedlocation)); /* getting JSON string from URL */ JSONObject json = jParser.makeHttpRequest(dealers_url, "GET", params); return json; } @Override protected void onPostExecute(JSONObject json) { // super.onPostExecute(aVoid); MatrixCursor cursor = new MatrixCursor(); try { /* Checking for SUCCESS TAG */ int success = json.getInt(TAG_SUCCESS); if (success == 1) { JSONArray JAStuff = json.getJSONArray(TAG_STUFF); /** CHECK THE NUMBER OF RECORDS **/ int intStuff = JAStuff.length(); //creating array dealerdetailsarray =new String[intStuff][12]; if (intStuff != 0) { String[] str1 = new String[JAStuff.length()]; for(int i=0;i<JAStuff.length();i++) { json=JAStuff.getJSONObject(i); // startManagingCursor(cursor); // dealerdetailsarray[0][0]=json.getString("dealername"); cursor.addRow(new String[] {json.getString("dealername"),json.getString("product"), json.getString("type"),json.getString("description"),json.getString("location"),json.getString("sublocation"),json.getString("address"),json.getString("phone1"),json.getString("phone2"),json.getString("auth"),json.getString("brands"),json.getString("lat"),json.getString("lon")}); } } } } catch (Exception e) { Log.e("test",e.toString()); } Toast.makeText(getApplicationContext(), cursor.getCount(),Toast.LENGTH_LONG).show(); } } }

先试试这个。

Android - 将列添加到Matrix光标并显示列数Toast导致崩溃

1 个答案: