无法在未调用looper.prepare（）的线程内创建处理程序

Question

I have an Activity in which im getting the results from XML via Async task. This is my code of the activity from which i am getting the prediction

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_prediction);

    Past = (TextView) findViewById(R.id.textView1);
    Present = (TextView) findViewById(R.id.textView2);
    Future = (TextView) findViewById(R.id.textView3);

    new GetPrediction().execute();

}       

class GetPrediction extends AsyncTask <Void, String, String> {

    ProgressDialog dialog = new ProgressDialog(Prediction.this);

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
        dialog.setMessage("Getting your fortune");
        dialog.setCancelable(false);
        dialog.show();
    }

    @Override
    protected String doInBackground(Void... b) {
        // TODO Auto-generated method stub
        try
        {
            URL website = new URL(baseUrl);
            SAXParserFactory spf = SAXParserFactory.newInstance();
            SAXParser sp = spf.newSAXParser();
            XMLReader xr = sp.getXMLReader();
            HandlingXMLReading doingWork = new HandlingXMLReading(); // created object of default handler class
            xr.setContentHandler(doingWork);
            xr.parse(new InputSource(website.openStream()));
           past = doingWork.getPastPrediction();
           present = doingWork.getPresentPrediction();
           future = doingWork.getFuturePrediction();

    } 
        catch( Exception e)
        {
            past = e.getMessage();
            present = e.getMessage();
            future = e.getMessage();
            }
        return past;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        dialog.dismiss();
        Past.setText(result);
        Present.setText(present);
        Future.setText(future);
    }

}

}

Now this works fine, but the problem is when this Async task call the Default handler class It gives me the above error. In default handler class I made an object of a class from which I am getting some numbers. I am using that numbers to parse the XML. But when I removed That class object the code works fine. Here is the code of HandleXMLData.class

public class HandlingXMLReading extends DefaultHandler {

// setting up the opbject
XMLDataCollection prediction = new XMLDataCollection();

/*These next 4 lines  gives the error of 
 * cannot create the handler inside thread
 */
SelectionFuture CardNo = new SelectionFuture();
int PastCard = CardNo.pastCardNo;
int PresentCard = CardNo.presentCardNo;
int FutureCard = CardNo.FutureCardNo;


/* Method Containing the Past Prediction*/
public String getPastPrediction()
{
    return prediction.Past();
}

/* Method Containing the Present Prediction*/
public String getPresentPrediction()
{
    return prediction.Present();
}

/* Method Containing the Past Prediction*/
public String getFuturePrediction()
{
    return prediction.Future();
}

@Override
public void startElement(String uri, String localName, String qName,
        Attributes attributes) throws SAXException {
    // TODO Auto-generated method stub
    super.startElement(uri, localName, qName, attributes);


     if (localName.equals("overview_prediction1")){
            String past = attributes.getValue("name");
            prediction.setPast(past);
            }

 if (localName.equals("overview_prediction2")){
        String present  = attributes.getValue("name");
        prediction.SetPresent(present);
        }

     if (localName.equals("overview_prediction3")){
        String future = attributes.getValue("name");
        prediction.SetFuture(future);
        }

}}

I am not able to understand what is happening. Thanks In advance

Answer 1

AsyncTask internally uses a Handler . A Handler basically allows you to post Runnables from another thread on the thread the handler was assigned to, which in the case of AsyncTask is always the thread from which it is called. so simplest method is creating object for your handler in void onCreate() ,instead of creating object inside of AsyncTask

Answer 2

Try this. This might solve your problem

private HandlingXMLReading doingWork;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_prediction);

    Past = (TextView) findViewById(R.id.textView1);
    Present = (TextView) findViewById(R.id.textView2);
    Future = (TextView) findViewById(R.id.textView3);
    doingWork = new HandlingXMLReading(); // created object of default handler class

    new GetPrediction().execute();

}       

class GetPrediction extends AsyncTask <Void, String, String> {

    ProgressDialog dialog = new ProgressDialog(Prediction.this);

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
        dialog.setMessage("Getting your fortune");
        dialog.setCancelable(false);
        dialog.show();
    }

    @Override
    protected String doInBackground(Void... b) {
        // TODO Auto-generated method stub
        try
        {
            URL website = new URL(baseUrl);
            SAXParserFactory spf = SAXParserFactory.newInstance();
            SAXParser sp = spf.newSAXParser();
            XMLReader xr = sp.getXMLReader();

            xr.setContentHandler(doingWork);
            xr.parse(new InputSource(website.openStream()));
            past = doingWork.getPastPrediction();
            present = doingWork.getPresentPrediction();
            future = doingWork.getFuturePrediction();

    } 
        catch( Exception e)
        {
            past = e.getMessage();
            present = e.getMessage();
            future = e.getMessage();
            }
        return past;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        dialog.dismiss();
        Past.setText(result);
        Present.setText(present);
        Future.setText(future);
    }

}