android Studio 中的 Logcat 錯誤

Question

當我運行我的項目時，錯誤顯示在 log cat 中，這對我來說是無法理解的，請任何人都可以幫助我這些錯誤的含義是什么意味着我在我的代碼中犯了什么錯誤。 即使我從谷歌下載其他項目，在運行相同的日志時，貓也顯示請幫忙。

LogCat 在這里：-

02-03 12:09:05.115 7614-7614/com.example.administrator.mainpage E/GMPM: GoogleService failed to initialize, status: 10, Missing an expected resource: 'R.string.google_app_id' for initializing Google services.  Possible causes are missing google-services.json or com.google.gms.google-services gradle plugin.
02-03 12:09:05.115 7614-7614/com.example.administrator.mainpage E/GMPM: Scheduler not set. Not logging error/warn.
02-03 12:09:05.240 7614-7639/com.example.administrator.mainpage E/GMPM: Uploading is not possible. App measurement disabled
02-03 12:09:06.371 7614-7689/com.example.administrator.mainpage E/GED: Failed to get GED Log Buf, err(0)
02-03 12:09:06.471 7614-7614/com.example.administrator.mainpage E/AndroidRuntime: FATAL EXCEPTION: main                                                 Process: com.example.administrator.mainpage, PID: 7614
    java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
    at android.widget.ArrayAdapter.getCount(ArrayAdapter.java:330)
    at android.widget.ListView.setAdapter(ListView.java:499)
    at com.example.administrator.mainpage.MainActivity$JSONTask.onPostExecute(MainActivity.java:56)
    at com.example.administrator.mainpage.MainActivity$JSONTask.onPostExecute(MainActivity.java:41)
    at android.os.AsyncTask.finish(AsyncTask.java:636)
    at android.os.AsyncTask.access$500(AsyncTask.java:177)
    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:653)
    at android.os.Handler.dispatchMessage(Handler.java:111)
    at android.os.Looper.loop(Looper.java:194)
    at android.app.ActivityThread.main(ActivityThread.java:5649)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:959)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:754)

這是代碼：-

  public class MainActivity extends AppCompatActivity {
      ListView lvCity;
      private static String url="14.140.200.186/Hospital/get_city.php";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.arjuncontent_main);
        new JSONTask().execute(url);

    }
    public class JSONTask extends AsyncTask<String,String, List<CityModel>>{
        private final ProgressDialog dialog = new ProgressDialog(MainActivity.this);

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            dialog.setMessage("Downloading Cities...");
            dialog.show();
        }

        @Override
        protected void onPostExecute( List<CityModel> result) {
            super.onPostExecute(result);
            CityAdapter adapter=new CityAdapter(getApplicationContext(),R.layout.city_single_row,result);
            lvCity = (ListView) findViewById(R.id.lvCity);
            lvCity.setAdapter(adapter);
        }
        public class CityAdapter extends ArrayAdapter {
            private List<CityModel> cityModelList;
            private int resource;
            private LayoutInflater inflater;
            public CityAdapter(Context context, int resource, List<CityModel> objects) {
                super(context, resource, objects);
                cityModelList=objects;
                this.resource=resource;
                inflater= (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
            }

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

                if (convertView==null)
                    convertView=inflater.inflate(resource,null);
                TextView cityname;
                TextView cityid;
                cityid= (TextView) convertView.findViewById(R.id.cityid);
                cityid.setText(cityModelList.get(position).getCity_id());
                cityname= (TextView)convertView.findViewById(R.id.cityname);
                cityname.setText(cityModelList.get(position).getCity_name());

                return  convertView;

            }
        }
        @Override
        protected  List<CityModel> doInBackground(String... params) {
            HttpURLConnection connection = null;
            BufferedReader reader = null;
            try {
                URL url = new URL(params[0]);
                connection = (HttpURLConnection) url.openConnection();
                connection.setRequestMethod("GET");
                connection.connect();
                InputStream stream = connection.getInputStream();
                reader = new BufferedReader(new InputStreamReader(stream));
                StringBuffer buffer = new StringBuffer();
                String line = "";
                while ((line = reader.readLine()) != null) {
                    buffer.append(line);
                }
                String finalJson=buffer.toString();
                JSONObject parentObject=new JSONObject(finalJson);
                JSONArray parentArray=parentObject.getJSONArray("Cities");
                List<CityModel>cityModelList=new ArrayList<>();
                for (int i=0; i<parentArray.length(); i++){
                    JSONObject finalObject = parentArray.getJSONObject(i);
                    CityModel cityModel=new CityModel();
                    cityModel.setCity_name(finalObject.getString("city_name"));
                    cityModel.setCity_id(finalObject.getString("city_id"));
                    cityModelList.add(cityModel);
                }
                return cityModelList;
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            } finally {
                if (connection != null)
                    connection.disconnect();
                ;
                try {
                    if (reader != null)
                        reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }


            return null;
        }


    }

`

Answer 1

您需要從開發者控制台下載配置文件並將其添加到您的項目中。 此鏈接的第二步。

文件名為 google-services.json

Answer 2

問題是刪除項目中的firebase組件后有firebase的痕跡，請確保刪除中介中的文件