使用齐射从服务器将数据提取到片段时出错

Question

我有一个来自url的json数据，我想从中使用volley库获取文本数据。我还有一个片段，其中将显示数据。

在获取数据后，Volley给了我一个错误，我不知道出了什么问题。

onErrorResponse函数被一次又一次地调用，并显示toast消息 - 出错了。

这是Fragment.java

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    final View view = inflater.inflate(R.layout.fragment, container, false);
    final TextView textView = view.findViewById(R.id.event_text);

}

JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST, Config.events_server, (String) null,

    new Response.Listener<JSONObject>() {
        @Override
        public void onResponse(JSONObject response) {
            try {
                textView.setText(response.getString("trending"));
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Toast.makeText(view.getContext(), "Something went wrong", Toast.LENGTH_SHORT).show();
            error.printStackTrace();

        }
    });

    MySingleton.getmInstance(view.getContext()).addToRequestQueue(jsonObjectRequest;
    return view;
}

和MySingleton.java

public class MySingleton {
    private static MySingleton mInstance;
    private static Context ctx;
    private RequestQueue requestQueue;
    private MySingleton(Context ctx) {
        this.ctx =ctx;
        requestQueue = getRequestQueue();
    }

    private RequestQueue getRequestQueue() {
        if(requestQueue == null) {
            requestQueue = Volley.newRequestQueue(ctx.getApplicationContext());
        }
        return requestQueue;
    }

    public static synchronized MySingleton getmInstance(Context context) {
        if(mInstance == null) {
            mInstance = new MySingleton(context);
        }
        return mInstance;
    }

    public <T>void addToRequestQueue(Request<T> request){
        getRequestQueue().add(request);
    }
}

Answer 1

试试这个：

在Singleton类中添加：

@Override
public void onCreate() {
    super.onCreate();

    // initialize the singleton
    mInstance = this;
}

:

  HashMap<String, String> params = new HashMap<>();
params.put("value","value" );
params.put("value", "value");
JSONObject par = new JSONObject(params);

JsonObjectRequest objectRequest = new JsonObjectRequest("url here", par,
        new Response.Listener<JSONObject>()
        {
            @Override
            public void onResponse(JSONObject response) {
            Log.d(" response", response.toString());
            }},
            new Response.ErrorListener()
            {
                @Override
                public void onErrorResponse(VolleyError error)
                {
                //handle error here

                }
            });


// Access the RequestQueue through your singleton class.
MyApplication.getInstance().addToRequestQueue(jsObjRequest);

如有任何进一步的疑问，请在评论中告诉我