Question

我在doInBackground方法的Asynctask类中面临值'return'的问题。我收到一个错误，关于'在下面的代码中缺少return语句。

`公共类ForecastNetwork扩展了AsyncTask {

    public final String TAG = ForecastNetwork.class.getSimpleName();

    @Override
    protected Void doInBackground(Void... params) {

        HttpURLConnection urlConnection = null;
        BufferedReader reader = null;

//将原始JSON响应包含为字符串。 String forecastJsonStr = null;

        try {
            // Construct the URL for the OpenWeatherMap query
            // Possible parameters are avaiable at OWM's forecast API page, at
            // http://openweathermap.org/API#forecast
            URL url = new URL("http://api.openweathermap.org/data/2.5/forecast/daily?q=94043&mode=json&units=metric&cnt=7");

            // Create the request to OpenWeatherMap, and open the connection
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.connect();

            // Read the input stream into a String
            InputStream inputStream = urlConnection.getInputStream();
            StringBuffer buffer = new StringBuffer();
            if (inputStream == null) {
                // Nothing to do.
                return null;
            }
            reader = new BufferedReader(new InputStreamReader(inputStream));

            String line;
            while ((line = reader.readLine()) != null) {
                // Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
                // But it does make debugging a *lot* easier if you print out the completed
                // buffer for debugging.
                buffer.append(line + "\n");
            }

            if (buffer.length() == 0) {
                // Stream was empty.  No point in parsing.
                return null;
            }
            forecastJsonStr = buffer.toString();
        } catch (IOException e) {
            Log.e(TAG, "Error ", e);
            // If the code didn't successfully get the weather data, there's no point in attemping
            // to parse it.
            return null;
        } finally {
            if (urlConnection != null) {
                urlConnection.disconnect();
            }
            if (reader != null) {
                try {
                    reader.close();
                } catch (final IOException e) {
                    Log.e(TAG, "Error closing stream", e);
                }
            }
        }


    }`

我最后应该回报什么？

Answer 1

我假设您忘记返回处理结果

    forecastJsonStr = buffer.toString();
    return forecastJsonStr;

Android Asynctask返回问题

1 个答案: