Remove elements from Webview using Javascript

Question

I want to remove the header of a Webview in an android App. I have found that it can be done programatically as:

Document document = Jsoup.connect(mUrl).get();
document.getElementsByClass("header").remove();
WebSettings ws = mWebView.getSettings();
ws.setJavaScriptEnabled(true);

mWebView.loadDataWithBaseURL(mUrl, document.toString(), "text/html", "utf-8", ""); 

The problem is that when the above code is executed, I receive a ThreadPolicyException. I think the cause is that too much work on main Thread is executed. I knowe there is a solution, which is though considered to be "quick and dirty":

ThreadPolicy tp = ThreadPolicy.LAX;
StrictMode.setThreadPolicy(tp);

The recommended solution is that the code should be excecuted in a Background Thread (or in an AsyncTask). When I try this however I receive also an Exception because of the call of methods on a Webview on a Thread other than the UIThread withe the message:

Calling View methods on another thread than the UI thread.; 
java.lang.IllegalStateException: Calling View methods on another thread than the UI thread.

What is then the appropriate "clean" solution to this issue?

Answer 1

Try insert your code inside runOniThread:

getActivity().runOnUiThread( new Runnable() {
    public void run() {
       ... your code
    }
});

In my case this work fine inside background Threads (run from Fragment).

Add:

Also may be best way is javascript-injection:

public class MyWebViewClient extends WebViewClient {

    @Override
    public void onPageFinished( WebView view, String url) {

        // ... 
        webview.loadUrl( "javascript: { document.getElementByClass('header').remove(); }");
        // ...
    }
}


  webview.setWebViewClient( new MyWebViewClient());