In android this program not retrieve the xml data after the progress bar loading help me

问题

\In android programming..i like to retrieve data's in the xmltags from url(xmlparsing) in the meantime i want to load progress until the data retrieve from xmltags. i attach my code check whether its rite or wrong thank you\

 \\main activity\\


public class act extends Activity
{

 \\button used to start the function after the click\\

    Button b;
    public ProgressDialog mDialog;
    @Override
     public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        b=(Button)findViewById(R.id.button1);
        b.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // TODO Auto-generated method stub
                new GetTask().execute();

            }
        });
}
   \\my asynctask\\

class GetTask extends AsyncTask<Object, Void, String>
{



    @Override
    protected void onPreExecute()
    {
        super.onPreExecute();

         mDialog = new ProgressDialog(act.this);
         mDialog.setMessage("Please wait...");
         mDialog.show();
    }
     @Override
    protected String doInBackground(Object... params)
    {

  \\ui programetically declare the textviews\\

                 try {
                    LinearLayout layout = new LinearLayout(act.this);
                    layout.setOrientation(1);
                    TextView no[];
                    TextView na[];
                    TextView c[];


                  URL url = new URL("http://api.androidhive.info/pizza/?format=xml");          
                  DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();          
                  DocumentBuilder db = dbf.newDocumentBuilder();
                  Document doc = db.parse(new InputSource(url.openStream()));
                  doc.getDocumentElement().normalize();
                  NodeList nodeList = doc.getElementsByTagName("item");
                  no = new TextView[nodeList.getLength()];
                  na = new TextView[nodeList.getLength()];
                  c = new TextView[nodeList.getLength()];

                  for (int i = 0; i < nodeList.getLength(); i++) {
                      Node node = nodeList.item(i);
                      no[i] = new TextView(act.this);
                      na[i] = new TextView(act.this);
                      c[i] = new TextView(act.this);
                      Element fstElmnt = (Element) node;

                      NodeList idlist = fstElmnt.getElementsByTagName("id");
                      Element numelement = (Element) idlist.item(0);
                      idlist = numelement.getChildNodes();
                      no[i].setText("ID="+ ((Node) idlist.item(0)).getNodeValue());

                      NodeList namelist = fstElmnt.getElementsByTagName("name");
                      Element namelement = (Element) namelist.item(0);
                      namelist = namelement.getChildNodes();
                      na[i].setText("pizza name="+ ((Node) namelist.item(0)).getNodeValue());

                      NodeList costlist = fstElmnt.getElementsByTagName("cost");
                      Element costlement = (Element) costlist.item(0);
                      costlist = costlement.getChildNodes();
                      c[i].setText("cost="+ ((Node) costlist.item(0)).getNodeValue());

                      layout.addView(no[i]);
                      layout.addView(na[i]);
                      layout.addView(c[i]);
                      setContentView(layout);

                      }} 
             catch (Exception e) {
                     }
        return null;

            }

            @Override
    protected void onPostExecute(String result)
    {
        super.onPostExecute(result);
        mDialog.dismiss(); 

            }
   }
  }

回答1:

The Following code is Wrong.

U dont have any data in your onPostExecute() so whatever youe want to display just show that thing in onPostExecute() instead of doInBackground().

So change it ..

A sample example u can find in LazyLoading Or Asynctask App:-

https://github.com/thest1/LazyList

https://github.com/ethervoid/android-async-task-example

May with following code u can get ur ans...!!!!

回答2:

First u cannot make the UI related actions in the doInBackground()

If u want u can do it in the onPostExecute() after completed the doInBackground() process ...

So change ur logic ..

回答3:

NodeList namelist;
String[] no,na,c;
 try {
              URL url = new URL("http://api.androidhive.info/pizza/?format=xml");          
              DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();          
              DocumentBuilder db = dbf.newDocumentBuilder();
              Document doc = db.parse(new InputSource(url.openStream()));
              doc.getDocumentElement().normalize();
              NodeList nodeList = doc.getElementsByTagName("item");

              no = new String[nodeList.getLength()];
              na = new String[nodeList.getLength()];
              c = new String[nodeList.getLength()];
              for (int i = 0; i < nodeList.getLength(); i++) {
                  Node node = nodeList.item(i);

                  Element fstElmnt = (Element) node;

                  NodeList idlist = fstElmnt.getElementsByTagName("id");
                  Element numelement = (Element) idlist.item(0);
                  idlist = numelement.getChildNodes();
                  no[i]=((Node) idlist.item(0)).getNodeValue();                     

                  NodeList namelist = fstElmnt.getElementsByTagName("name");
                  Element namelement = (Element) namelist.item(0);
                  namelist = namelement.getChildNodes();
                  na[i]=((Node) namelist.item(0)).getNodeValue()

                  NodeList costlist = fstElmnt.getElementsByTagName("cost");
                  Element costlement = (Element) costlist.item(0);
                  costlist = costlement.getChildNodes();


                  }} 
         catch (Exception e) {
                 }
    return null;

        }

        @Override
protected void onPostExecute(String result)
{
    super.onPostExecute(result);
                LinearLayout layout = new LinearLayout(act.this);
                layout.setOrientation(1);
                TextView no[];
                TextView na[];
                TextView c[];
              no = new TextView[nodeList.getLength()];
              na = new TextView[nodeList.getLength()];
              c = new TextView[nodeList.getLength()];
              for (int i = 0; i < nodeList.getLength(); i++) {

                  no[i] = new TextView(act.this);
                  na[i] = new TextView(act.this);
                  c[i] = new TextView(act.this);
                  no[i].setText("ID="+no[i] );
                 na[i].setText("pizza name="+ na[i]);
                c[i].setText("cost="+ ((Node) costlist.item(0)).getNodeValue());

                  layout.addView(no[i]);
                  layout.addView(na[i]);
                  layout.addView(c[i]);
                  setContentView(layout);
    mDialog.dismiss(); 

        }

来源：https://stackoverflow.com/questions/14494913/in-android-this-program-not-retrieve-the-xml-data-after-the-progress-bar-loading