Question

我正在做一个移动应用程序，它从我自己的API中检索信息。我正在尝试用JSON获取餐馆详细信息并解析它们以进行显示。这是我得到的错误：

D/ViewRootImpl: MSG_RESIZED_REPORT: ci=Rect(0, 0 - 0, 0) vi=Rect(0, 0 - 0, 0) or=1
 I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@cf94aa3 time:148477558
 E/MainActivity: Response from url: {
              "address1": "Market Square, Smithfield, Dublin Dublin 7", 
              "address2": "Dublin 7", 
              "cost": 35, 
              "lat": 53.3489980000, 
              "lng": -6.2788120000, 
              "menu_type": "BBQ", 
              "name": "My Meat Wagon", 
              "offer": "Meal for 10\u20ac", 
              "phone": 53463267, 
              "rate": 4.1
            }
 E/MainActivity: Json parsing error: No value for restaurants
 D/ViewRootImpl: #3 mView = null

这是我正在使用的代码：

protected Void doInBackground(Void... arg0) {
        HttpHandler sh = new HttpHandler();

        // Making a request to url and getting response
        String jsonStr = sh.makeServiceCall(url);

        Log.e(TAG, "Response from url: " + jsonStr);

        if (jsonStr != null) {
            try {
                JSONObject jsonObj = new JSONObject(jsonStr);

                // Getting JSON Array node
                JSONArray restaurants = jsonObj.getJSONArray("restaurants");

                // looping through the JSON object
                    JSONObject c = restaurants.getJSONObject(0);

                    String name = c.getString("name");
                    String address1 = c.getString("address1");
                    String address2 = c.getString("address2");
                    String lat = c.getString("lat");
                    String lng = c.getString("lng");
                    String cost = c.getString("cost");
                    String menu_type = c.getString("menu_type");
                    String rate = c.getString("rate");
                    String offer = c.getString("offer");


                    // Phone node is JSON Object
                    String mobile = c.getString("mobile");
                    // tmp hash map for single restaurant
                    HashMap<String, String> restaurant = new HashMap<>();

                    // adding each child node to HashMap key => value
                    restaurant.put("name", name);
                    restaurant.put("address1", address1);
                    restaurant.put("address2", address2);
                    restaurant.put("lat", lat);
                    restaurant.put("lng", lng);
                    restaurant.put("cost", cost);
                    restaurant.put("menu_type", menu_type);
                    restaurant.put("rate", rate);
                    restaurant.put("offer", offer);
                    restaurant.put("mobile", mobile);

                    contactList.add(restaurant);

            } catch (final JSONException e) {
                Log.e(TAG, "Json parsing error: " + e.getMessage());
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(),
                                "Json parsing error: " + e.getMessage(),
                                Toast.LENGTH_LONG)
                                .show();
                    }
                });

            }
        } else {
            Log.e(TAG, "Couldn't get json from server.");
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(getApplicationContext(),
                            "Couldn't get json from server. Check LogCat for possible errors!",
                            Toast.LENGTH_LONG)
                            .show();
                }
            });

        }

        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        // Dismiss the progress dialog
        if (pDialog.isShowing())
            pDialog.dismiss();
        /**
         * Updating parsed JSON data into ListView
         * */
        ListAdapter adapter = new SimpleAdapter(
                MainActivity.this, contactList,
                R.layout.list_item, new String[]{"name", "address1",
                "address2","lat","lng","menu_type","Phone","rate","offer","cost"}, new int[]{R.id.name,
                R.id.address1, R.id.address2,R.id.lat,R.id.lng,R.id.menu,R.id.mobile,R.id.rate,R.id.offer,R.id.cost});

        lv.setAdapter(adapter);
    }

}
   }

Answer 1

当只有一个结果时，许多API不会返回数组。您将要使用optJSONArray，如果它返回null，请检查它是否是单个结果（使用其他opt方法），如果是，则跳过数组步骤。

https://docs.oracle.com/middleware/maf230/mobile/api-ref/oracle/adfmf/json/JSONObject.html#optJSONArray-java.lang.String-

Answer 2

我建议使用Google Gson库来解析json字符串。

基本上你需要导入库，创建相应的POJO并调用gson.fromJson（jsonStringToParseFrom，YourPOJOClassName.class）。所以你的doInBackground看起来像：

protected Void doInBackground(Void... arg0) {
    HttpHandler sh = new HttpHandler();

    // Making a request to url and getting response
    String jsonStr = sh.makeServiceCall(url);

    Gson gson = new Gson();
    YourPOJOClass parsedResponse = gson.fromJson(jsonStr, YourPOJOClass.class);

如果在gson中会出现一些解析问题，你会得到明确错误的异常，你将摆脱所有的样板解析代码。

JSON解析错误变量没有值

2 个答案: