Question

我有一个按钮，当按下该按钮时，它会计算出乘车费用和其他活动的意图，但是当按下时，会出现系统错误：

System.err: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.toString()' on a null object reference

查找了此错误的其他实例，并尝试了解决方法，但似乎不适用于我。就Android而言，我是菜鸟。

按钮

else if (btnStartTrip.getText().equals("DROP OFF HERE")) {
                // arriving at destination with customer ....
                calculateCashFee(pickupLocation, Common.mLastLocation);

calculateCashFee

错误在这行，第二次尝试，抓住：

JSONObject jsonObject = new JSONObject(response.body().toString());

private void calculateCashFee(final Location pickupLocation, Location mLastLocation) {

        String requestApi = null;

        try {
            requestApi = "https://maps.googleapis.com/maps/api/directions/json?" +
                    "mode=driving&transit_routing_preference=less_driving" +
                    "&origin="+ pickupLocation.getLatitude() + ","+ pickupLocation.getLongitude() +
                    "&tap_destination=" + mLastLocation.getLatitude() + ", " + mLastLocation
                    .getLongitude() + "&key=" + getResources().getString(R.string.google_directions_api);

            mService.getPath(requestApi).enqueue(new Callback<String>() {
                @Override
                public void onResponse(Call<String> call, Response<String> response) {

                    try {
                        // Extract json
                        // Root Object
                        JSONObject jsonObject = new JSONObject(response.body().toString()); // System error

                        JSONArray routes = jsonObject.getJSONArray("routes");
                        JSONObject object = routes.getJSONObject(0);

                        JSONArray legs = object.getJSONArray("legs");
                        JSONObject legsObject = legs.getJSONObject(0);

                        // Get Distance
                        JSONObject distance = legsObject.getJSONObject("distance");
                        String distance_text = distance.getString("text");

                        // Only take number string to parse
                        Double distance_value = Double.parseDouble(distance_text
                                .replaceAll("[^0-9\\\\.]+", ""));

                        // Get Time
                        JSONObject timeObject = legsObject.getJSONObject("duration");
                        String time_text = timeObject.getString("text");

                        // Only take number string to parse
                        Double time_value = Double.parseDouble(time_text
                                .replaceAll("[^0-9\\\\.]+", ""));

                        sendDropOffNotification(customerId);

                        Intent intent = new Intent(DriverTracking.this,
                                DriverTripDetail.class);
                        intent.putExtra("start_address", legsObject
                                .getString("start_address"));
                        intent.putExtra("end_address", legsObject
                                .getString("end_address"));
//                        intent.putExtra("time", String.valueOf(time_value)); ---> not using
                        intent.putExtra("distance", String.valueOf(distance_value));
                        intent.putExtra("total", Common.formulaPrice(
                                distance_value));
                        intent.putExtra("location_start", String.format(Locale.CANADA,
                                "%f, %f", pickupLocation.getLatitude(),
                                pickupLocation.getLongitude()));
                        intent.putExtra("location_end", String.format(Locale.CANADA,
                                "%f, %f", Common.mLastLocation.getLatitude(),
                                Common.mLastLocation.getLongitude()));

                        startActivity(intent);
                        finish();

                    } catch (Exception e) {
                        e.printStackTrace();

                    }
                }

                @Override
                public void onFailure(Call<String> call, Throwable t) {
                    Toast.makeText(DriverTracking.this, "" + t.getMessage(),
                            Toast.LENGTH_SHORT).show();
                }
            });

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

我在名为“模块”的文件夹中还有其他相关的代码

DirectionFinder

private class DownloadRawData extends AsyncTask<String, Void, String> {

        @Override
        protected String doInBackground(String... params) {
            String link = params[0];
            try {
                URL url = new URL(link);
                InputStream is = url.openConnection().getInputStream();
                StringBuffer buffer = new StringBuffer();
                BufferedReader reader = new BufferedReader(new InputStreamReader(is));

                String line;
                while ((line = reader.readLine()) != null) {
                    buffer.append(line + "\n");
                }

                return buffer.toString();

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String res) {
            try {
                parseJSon(res);
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }

    private void parseJSon(String data) throws JSONException {
        if (data == null)
            return;

        List<Route> routes = new ArrayList<Route>();
        JSONObject jsonData = new JSONObject(data);
        JSONArray jsonRoutes = jsonData.getJSONArray("routes");
        for (int i = 0; i < jsonRoutes.length(); i++) {
            JSONObject jsonRoute = jsonRoutes.getJSONObject(i);
            Route route = new Route();

            JSONObject overview_polylineJson = jsonRoute.getJSONObject("overview_polyline");
            JSONArray jsonLegs = jsonRoute.getJSONArray("legs");
            JSONObject jsonLeg = jsonLegs.getJSONObject(0);
            JSONObject jsonDistance = jsonLeg.getJSONObject("distance");
            JSONObject jsonDuration = jsonLeg.getJSONObject("duration");
            JSONObject jsonEndLocation = jsonLeg.getJSONObject("end_location");
            JSONObject jsonStartLocation = jsonLeg.getJSONObject("start_location");

            route.distance = new Distance(jsonDistance.getString("text"), jsonDistance
                    .getInt("value"));
            route.duration = new Duration(jsonDuration.getString("text"), jsonDuration
                    .getInt("value"));
            route.endAddress = jsonLeg.getString("end_address");
            route.startAddress = jsonLeg.getString("start_address");
            route.startLocation = new LatLng(jsonStartLocation.getDouble("lat"),
                    jsonStartLocation.getDouble("lng"));
            route.endLocation = new LatLng(jsonEndLocation.getDouble("lat"),
                    jsonEndLocation.getDouble("lng"));
            route.points = decodePolyLine(overview_polylineJson.getString("points"));

            routes.add(route);
        }

        listener.onDirectionFinderSuccess(routes);
    }

Answer 1

实际上，您的responsebody可能为null，如果您尝试将toString()设为null对象，则会抛出错误。

将其放入以下条件

if(response.body() != null){

// put here you complete code
JSONObject jsonObject = new JSONObject(response.body().toString());

}

您也可以尝试在try catch块中添加代码以防止崩溃。

Answer 2

在阅读代码时，目标位置似乎不包含“ .getLongitude（）”。现在可以正常工作了。

无效的API地址崩溃

2 个答案: