Question

我正在使用一个异步库来获取天气预报，但是即使我没有收到有关天气的信息，我的代码仍然继续。有什么办法等待答案吗？还是您知道有什么可以帮助我的吗？

Answer 1

代码继续进行就可以了。您应该使用回调来接收数据。有关更多详细信息，请附加您的功能。

Answer 2

WeatherClass.java

public class WeatherClass {

    private static double temp = 0.0;


    public static double getTemp(double latitude, double longitude, Context context){
        String OPEN_WEATHER_MAP_API = "xxxxxxxxx";
        new WeatherManager(OPEN_WEATHER_MAP_API).getFiveDayForecastByCoordinates(latitude,longitude,
                new WeatherManager.ForecastHandler() {
                    @Override
                    public void onReceivedForecast(WeatherManager manager, Forecast forecast) {
                        // Handle forecast

                        List<Double> list = new ArrayList<>();
                        for (int i = 0; i < 5; i++) {
                            long timestamp = forecast.getTimestampByIndex(i+3);
                            Weather weatherForTimestamp = forecast.getWeatherForTimestamp(timestamp);
                            Temperature tempMini = weatherForTimestamp.getTemperature().getMinimum();
                            double temperatureInCelcius = tempMini.getValue(TemperatureUnit.CELCIUS);
                            list.add(temperatureInCelcius);
                            Log.v("Weather", "" +weatherForTimestamp.getWind().getSpeed());
                            Log.v("Weather", "Température mini : " +  " "+ list.get(i));
                        }
                        int  minIndex = list.indexOf(Collections.min(list));
                        Log.v("Weather MINI", "Température mini : " + list.get(minIndex));
                        //Toast.makeText(context, "Température mini: " + list.get(minIndex), Toast.LENGTH_LONG).show();
                        temp =  list.get(minIndex);
                        Log.v("WeatherClass", temp + "");




                    }

                    @Override
                    public void onFailedToReceiveForecast(WeatherManager manager) {
                        Log.v("TAG",  " ERREUR");
                        temp = -1000000;

                    }
                }
        );
        return temp;
    }



}

Answer 3

您的代码运行：

创建获取数据的请求。
返回温度= 0.0
从服务器接收数据并更新温度。

因此，您运行代码将获得返回值= 0.0。

要解决此问题，您可以执行以下操作：

创建新界面。 IResult.java

public interface IResult {
    void onResult(double temp);
}

更新getTemp方法：

 public static void getTemp(double latitude, double longitude, final IResult callback){
        String OPEN_WEATHER_MAP_API = "xxxxxxxxx";
        new WeatherManager(OPEN_WEATHER_MAP_API)
        .getFiveDayForecastByCoordinates(latitude,longitude,
                new WeatherManager.ForecastHandler() {
                    @Override
                    public void onReceivedForecast(WeatherManager manager, Forecast forecast) {
                        // Handle forecast

                        List<Double> list = new ArrayList<>();
                        for (int i = 0; i < 5; i++) {
                            long timestamp = forecast.getTimestampByIndex(i+3);
                            Weather weatherForTimestamp = forecast.getWeatherForTimestamp(timestamp);
                            Temperature tempMini = weatherForTimestamp.getTemperature().getMinimum();
                            double temperatureInCelcius = tempMini.getValue(TemperatureUnit.CELCIUS);
                            list.add(temperatureInCelcius);
                            Log.v("Weather", "" +weatherForTimestamp.getWind().getSpeed());
                            Log.v("Weather", "Température mini : " +  " "+ list.get(i));
                        }
                        int  minIndex = list.indexOf(Collections.min(list));
                        Log.v("Weather MINI", "Température mini : " + list.get(minIndex));
                        //Toast.makeText(context, "Température mini: " + list.get(minIndex), Toast.LENGTH_LONG).show();
                        temp =  list.get(minIndex);
                        Log.v("WeatherClass", temp + "");
                        callback.onResult(temp);



                    }

                    @Override
                    public void onFailedToReceiveForecast(WeatherManager manager) {
                        Log.v("TAG",  " ERREUR");
                        temp = -1000000;
                        callback.onResult(temp);

                    }
                }
        );
    }

使用

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    WeatherClass.getTemp(32.32, 322.3, new IResult() {
        @Override
        public void onResult(double temp) {
            //result here
        }
    });
}

更新：因为是第一次启动，所以此方法在更新温度之前返回0.0（步骤2返回温度，步骤3更新温度），因此您将获得0.0。第二次启动，此方法将返回第一次启动的结果（因为它在更新temp之前返回temp），因此您可能认为它是正确的（但不正确，返回值是第一次启动的数据）。

如何强制异步任务等待答案？

3 个答案: