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我在doInBackground方法的Asynctask类中的值'return'中遇到问题。我得到一个错误,关于'在下面的代码中缺少return语句。Android Asynctask返回问题
'公共类ForecastNetwork扩展的AsyncTask {
public final String TAG = ForecastNetwork.class.getSimpleName();
@Override
protected Void doInBackground(Void... params) {
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
//将包含原始JSON响应作为一个字符串。 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);
}
}
}
}`
我最后应该返回什么?
我必须在最后写?实际上,我正在通过udacity举办的Google开发者开展在线课程,他们没有做过任何类似的事情。 – Rebecca
是否重要,如果我改变为结果参数,即公共类ForecastTask扩展公共类ForecastTask扩展?帮我。我真的很黑。 –
Rebecca
谢谢。其实它按照你的说法工作。:) – Rebecca