0

我有一个活动，我通过异步任务从 XML 获取结果。这是我从中获得预测的活动代码

@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);
    }

}

}

现在这工作正常，但问题是当这个异步任务调用默认处理程序类时它给了我上述错误。在默认处理程序类中，我创建了一个从中获取一些数字的类的对象。我正在使用这些数字来解析 XML。但是当我删除那个类对象时，代码工作正常。这是 HandleXMLData.class 的代码

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);
        }

}}

我无法理解发生了什么。提前致谢

4

2 回答 2

0

尝试这个。这可能会解决您的问题

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);
    }

}
于 2013-03-20T12:15:30.243 回答
0

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

于 2013-03-20T11:35:53.077 回答