处理网页时显示加载图标

Question

My MainActivity calls HandleWebPage.init() to download and parse a web page link. After init() call, I will get set of strings (3 strings) . Each string is shown in a separate fragment (default first fragment with first string). Other fragments can be selected via navigation drawer.

Issue is I am trying to add progress dialog which should show loading icon (rotating circle) till Handle Webpage.init() gets completed.

init() function internally calls 2 async tasks ; One to download the web page and second is to process the web page using jsoup to get above strings.

How can I add progress dialog to while init() function getting processed and returned to MainActivity?

I have tried adding init() in AsyncTask and putting progress dialog in onPreExecution etc.., did not work. Also tried to create progressdialog.show() then create a thread and started and called init() did not work. I would like to know what would be right solution Below is code snippet.

MainActivity.java /// ------------snip
if(savedInstanceState == null) {
            updateYearMonthDay();  //gets year, month, day
            //hwp is instance of HandleWebPage class
            // hwp.init() internally downloads a webpage and process
            // This takes some time and I require to show some progress around this
            hwp.init(year, month, day);  
            // after complete i get 3 strings which is processed further in below function
            updateMetaData();
            // this show first fragment with fist string in text view.
            SelectItem(0);

        }

HandleWebPage.java
--------------------
public void init()
{
           doc = downloadPage();
           if (doc != null) {
                  extractlinks(doc);
           }
// some other function which uses AsyncTask as 
String = new getmoreInfo().execute(dataString1).get();
}

public Document downloadPage()
{
try {
        doc = new getWebPage().execute(urlString).get();
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ExecutionException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return doc;       
}

public class getWebPage extends AsyncTask<String, Document , Document> {

    @Override
    protected void onPreExecute() {
    }

    @Override
    protected Document doInBackground(String... params) {
        try {
            doc = Jsoup.connect(params[0]).timeout(0).get();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        if(doc == null) {
            return null;
        } else
            return doc;
    }

    @Override
    protected void onPostExecute(Document doc1) {
        super.onPostExecute(doc1);
    }
};

public void extractLinks(Document doc)
{
// code to process doc using jsoup and update respective String in this class.
}

Answer 1

You can probably merge the two AsyncTask s that you perform sequentially into a single AsyncTask. For showing a progressbar during the AsyncTask , initialize the progressbar with a visibility of GONE when the activity is created. Then set the visibility to VISIBLE in the onPreExecute() method of AsyncTask and set it back to GONE in onPostExecute() method.