Method setText must be called from the UI thread

问题

Have read all the set and get called from the UI thread, on stackoverflow but none seems relevent. this code worked 2years ago, recently opened it. and it shows this error. "Method setText must be called from the UI thread".
What updates are doing this? marked the setText lines with comments to make it more clear. Any sugestions?

public class MainActivity extends Activity {

    static final String baseURL = "http://api.yr.no/weatherapi/locationforecast/1.9/?lat=";
TextView dato, grader, vindhastighet, vindretning;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.mainactivity);
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder() .detectAll().penaltyLog().build();     StrictMode.setThreadPolicy(policy);


        SmartLocation.with(this).location()
                .oneFix()
                .start(new OnLocationUpdatedListener() {
                    @Override
                    public void onLocationUpdated(Location location) {

                        dato = (TextView)findViewById(R.id.gpsbydato_txt);
                        grader = (TextView)findViewById(R.id.gpsbygrader_txt);
                        vindhastighet = (TextView)findViewById(R.id.gpsbyvindhastighet_txt);
                        vindretning = (TextView)findViewById(R.id.gpsbyvindretning_txt);

                        Double latitude = location.getLatitude();
                        Double longtitude = location.getLongitude();

                        StringBuilder Url = new StringBuilder(baseURL);
                        Url.append(latitude + ";lon=" + longtitude);
                        final String fullUrl = Url.toString();


                        class Read extends AsyncTask<String, Integer, String> {
                            @Override
                            protected String doInBackground(String... arg0) {

                                try {
                                    URL website = new URL(fullUrl);
                                //xmlreader parser data
                                    SAXParserFactory spf = SAXParserFactory.newInstance();
                                    SAXParser sp = spf.newSAXParser();
                                    XMLReader xr = sp.getXMLReader();
                                    HandlingXMLStuff doingWork = new HandlingXMLStuff();
                                    xr.setContentHandler(doingWork);
                                    xr.parse(new InputSource(website.openStream()));

                                    String informationTemp = doingWork.getInformationTemp();
                                    String informationVindretning = doingWork.getInformationVindretning();
                                    String informationVindhastighet = doingWork.getInformationVindhastighet(); 
//grader.setText is causing the error.
                                    grader.setText(informationTemp);
//vindhastighet.setText is causing the error.  

                                    vindhastighet.setText(informationVindhastighet);
//vindretning.setText is causing the error.  

                                    vindretning.setText(informationVindretning);

                                } catch (Exception e) {
                                    Log.e("URL:", fullUrl);
                                    dato.setText("erroorrr"); //also this setText
                                    System.out.println(e);
                                }


                                return null;
                            }

                            @Override
                            protected void onPostExecute(String result) {
                                dato.setText(result);
                                super.onPostExecute(result);
                            }
                        }

                        }

    });
}
}

回答1:

You can not update UI from doInBackground in AsyncTask.

All UI related operations need to be done inside UI thread.

You can use runonUithread to update text in your textview inside doInBackground

Here is an example

Code:

  @Override
protected String doInBackground(String... arg0) {

    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            grader.setText(informationTemp);
            vindhastighet.setText(informationVindhastighet);
            vindretning.setText(informationVindretning);

        }
    });

}

Or..better solution is to move your setText() code inside onPostExecute()

回答2:

StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder() .detectAll().penaltyLog().build();     StrictMode.setThreadPolicy(policy);

That was actually turning off strict mode, which allowed unsafe things like updating the UI on non-UI threads and instead of crashing log it to disk. This isn't actually allowed anymore. So your code was always wrong, you were just ignoring the wrongness and hoping you wouldn't get caught. The correct fix is to move your code to the UI thread, and probably delete all mentions of StrictMode throughout your codebase- it should only be used as a debugging tool, and probably not even then.

And all the advice on not updating the UI from threads is absolutely relevant- you're setting the UI on an AsyncTask in doInBackground- so from another thread. Move that to the UI thread by either runOnUiThread, a handler, or by putting it off until onPostExecute or a progress message.

回答3:

You have to update UI from UI thread. As its not possible to update UI from doInBackground(), you can use runOnUiThread() to do update UI operations:

Try this:

@Override
protected String doInBackground(String... arg0) {

    ...........
    ...................

    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            grader.setText(informationTemp);
            vindhastighet.setText(informationVindhastighet);
            vindretning.setText(informationVindretning);

        }
    });

    .............
    .....................
}

来源：https://stackoverflow.com/questions/43924166/method-settext-must-be-called-from-the-ui-thread