I was parsing web page and I got a Error

This is my code

private class DownloadWebpageTask extends AsyncTask<String, Void, String> {
    protected String doInBackground(String...urls){
        try{ return (String)downloadUrl((String)urls[0]); }
        catch( IOException e){return "download fail"; }
    }

    protected void onPostExecute(String result){
        String word ="";
        int start = -1;
        int end=-1;

        String tag_start="<title>";
        String tag_end= "</title>";

        start = result.indexOf(tag_start);
        if(start != -1){
            end = result.indexOf(tag_end);

            if(end != -1){
                word=result.substring(start+tag_start.length(), end);
                text.append("result : "+word+", start : "+start+" , end:"+end);
            }
            else
                text.append("there is no data");
        }
        else
            text.append("there is no data");

    }


}

Its about parsing the web page. and then I got this error I don't know what is wrong could you help me?

This is a error