如何修复java.lang.ClassCastException ...无法强制转换接口

Question

In my main activity i have a fragment which displays weather information. I have an interface between the fragment and the main activity that sends data from fragment to activity. The problem is when trying to specifically enter the fragment activity the app crashes and this error is displayed.

Any help or any alternative ways doing it would be appreciated.

    private void loadData() {
        final List<WeatherForeCast> listWeatherForeCasts = new ArrayList<>();
        StringRequest stringRequest = new StringRequest(Request.Method.GET,
                "https://www.metaweather.com/api/location/3534/",
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            JSONObject jsonObject = new JSONObject(response);
                            JSONArray array = jsonObject.getJSONArray("consolidated_weather");
                            JSONObject jsonObject1 = jsonObject.getJSONObject("parent");
                            String cityCountry = jsonObject1.getString("title");
                            cityCountry = cityCountry + " ," + jsonObject.getString("title");
                            textViewCity.setText(Html.fromHtml(cityCountry ));

                            for (int x = 0; x < 6; x++) {
                                JSONObject weatherObject = array.getJSONObject(x);
                                WeatherForeCast weatherForeCast = new WeatherForeCast(
                                        weatherObject.getInt("air_pressure"),
                                        weatherObject.getInt("wind_speed"),
                                        weatherObject.getInt("the_temp"),
                                        weatherObject.getInt("humidity"),
                                        weatherObject.getString("weather_state_name"),
                                        weatherObject.getString("applicable_date"));
                                listWeatherForeCasts.add(weatherForeCast);
                                weatherState = listWeatherForeCasts.get(0).getWeatherState();
                                if(x == 0) {
                                    sendData();
                                }
                            }
                            ;
                            adapter = new Adapter(listWeatherForeCasts, getActivity());
                            recyclerView.setAdapter(adapter);

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Toast.makeText(getActivity(), error.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                });
        RequestQueue requestQueue = Volley.newRequestQueue(getActivity());
        requestQueue.add(stringRequest);

    }




    public void sendData()
    {
        Log.i("fault", weatherState);
        getFirstWeatherInterface getFirstWeather = (getFirstWeatherInterface) getActivity();
        getFirstWeather.getFirst(weatherState);

    }

//Interface is implemented in the Activity
    @Override
    public WeatherForeCast getFirst(String string) {

        Log.i("fault2", string);
        return null
}

java.lang.ClassCastException: com.fan4.outdoorplus.WeatherFragments.WeatherActivity cannot be cast to com.fan4.outdoorplus.getFirstWeatherInterface
        at com.fan4.outdoorplus.WeatherFragments.WeatherFragment.sendData(WeatherFragment.java:143)
        at com.fan4.outdoorplus.WeatherFragments.WeatherFragment$1.onResponse(WeatherFragment.java:117)
        at com.fan4.outdoorplus.WeatherFragments.WeatherFragment$1.onResponse(WeatherFragment.java:92)
        at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:82)
        at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:29)
        at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:102)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Answer 1

Your problem is in this line. You are trying casting your activity to getFirstWeatherInterface

getFirstWeatherInterface getFirstWeather = (getFirstWeatherInterface) getActivity();