我的代码有效，但我在监视器中有这个异常消息：I / Choreographer：跳过37帧！应用程序可能在其主线程上做了太多工作。
我理解这个错误消息意味着我在UI线程中做了很多重要的处理。问题是，对我来说，除了将假数据添加到ListView之外，我几乎没有在UI线程上做任何事情。我正在使用AsyncTask来发出API请求，这是我正在做的唯一“重型”工作，并且它不在主线程中。
我把所有代码放在这里，但我认为大部分代码都不是问题，因为当我评论我所有的假数据代码和对AsyncTask的调用时，我仍然有这个问题。所以我想问题更多的是关于我如何使用这个片段，因为我从未使用过它，所以我肯定在任何地方犯了错误......
//==== list_item_forecast.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:id="@+id/list_item_forecast_textview" />
//====fragment_main.xml
<?xml version="1.0" encoding="utf-8"?>
<!-- using a FrameLayout because only one child element -->
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/listview_forecast"/>
</FrameLayout>
//==== content_main.xml
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/fragment"
android:name="com.example.android.sunshine.app.MainActivityFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:layout="@layout/fragment_main" />
//==== MainActivity
public class MainActivity extends AppCompatActivity implements ForecastRequest {
private static String appId = "";
// Will contain the raw JSON response as a string.
String forecastJsonStr = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Get OpenWeather API key
appId = getResources().getString(R.string.APPID);
try {
// Construct the URL for the OpenWeatherMap query
// Possible parameters are avaiable at OWM's forecast API page, at
// http://openweathermap.org/API#forecast
String url = "http://api.openweathermap.org/data/2.5/forecast/daily? q=94043&mode=json&units=metric&cnt=7&APPID=" + appId;
OpenWeatherRequest request = new OpenWeatherRequest();
request.response = this;
request.execute(url);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void requestDone(String jsonResponse) {
forecastJsonStr = jsonResponse;
Log.d(Constants.LOG_TAG,forecastJsonStr);
}
}
//==== Interface used to get result from AsyncTask in MainActivity
public interface ForecastRequest {
void requestDone(String output);
}
//==== The AsyncTask that make a request to OpenWeather API
public class OpenWeatherRequest extends AsyncTask<String, Integer, String> {
// These two need to be declared outside the try/catch
// so that they can be closed in the finally block.
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
// Will contain the raw JSON response as a string.
String forecastJsonStr = null;
public ForecastRequest response = null;
protected void onPreExecute() {
Log.d(Constants.LOG_TAG,"Fetching data...");
}
protected String doInBackground(String... urls) {
try {
URL url = new URL(urls[0]);
// 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) {
throw new Exception("No data");
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
return null;
}
forecastJsonStr = buffer.toString();
} catch (Exception e) {
e.printStackTrace();
}
return forecastJsonStr;
}
protected void onPostExecute(String result) {
response.requestDone(result);
}
}
//==== The fragment
public class MainActivityFragment extends Fragment {
private ArrayAdapter<String> mForecastAdapter;
ArrayList<String> weekForecast;
private ListView mListView;
public MainActivityFragment() {
}
public void onViewCreated(View view, Bundle savedInstanceState) {
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
//=== Add fake data
weekForecast = new ArrayList<>(Arrays.asList(
"Today - Sunny - 88/63",
"Tomorrow - Foggy - 70/40",
"Weds - Cloudy - 72/63",
"Thurs - Asteroids - 75/65",
"Fri - Heavy Rain - 65/56",
"Sat - HELP TRAPPED IN WEATHERSTATION - 60/51",
"Sun - Sunny - 80/68")
);
mForecastAdapter = new ArrayAdapter<>(
// The current context (this fragment parent activity)
getActivity(),
// ID of list item layout
R.layout.list_item_forecast,
// ID of the textview to populate
R.id.list_item_forecast_textview,
// Data
weekForecast);
mListView = (ListView)rootView.findViewById(R.id.listview_forecast);
mListView.setAdapter(mForecastAdapter);
return rootView;
}
}
答案 0 :(得分：2)
我刚尝试使用手机而不是Android Studio模拟器，消息就消失了。所以问题来自模拟器而不是我的代码。