如何在应用程序的某些活动中解决诸如ANR之类的错误？

Question

I use Asynctask in my activity and i want to fetch html content of url using asynctask ...I am geeting html content successfully some time but sometime not happen anything..I cant't get content of html and its giving me black screen and give error of ANR...

My Activity coding...

public class ControlActivity extends AppCompatActivity {

    private static TextView txt1, txt2, txt3, txt4,txt5,txt6,txt7,txt8;
    private static SwitchCompat switch1, switch2, switch3, switch4, switch5, switch6, switch7, switch8;
  //  private static ImageView image1,image2,image3,image4,image5,image6,image7,image8;
    private static Button allon,alloff;
    String t1,t2,t3,t4,t5,t6,t7,t8;


    SwipeRefreshLayout swipe_container;

    JSONArray data = null;

    Handler mHandler;
    private static String ip,port,uname,password;
    private static Document htmlDocument;
    private static String htmlContentInStringFormat,content;
    private static String stringuri;
    private static List<String> listOfString = new ArrayList<String>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_control);
        new JSONAsyncTask().execute();
class JSONAsyncTask extends AsyncTask<String, Void, Boolean> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();

        }

        @Override
        protected Boolean doInBackground(String... urls) {
            StringBuffer stringBuffer = new StringBuffer("");
            BufferedReader bufferedReader = null;
            try {
                HttpClient httpClient = new DefaultHttpClient();
                HttpGet httpGet = new HttpGet();

                URI uri = new URI("http://"+ip+":"+port+"/index.htm");

                httpGet.setURI(uri);
                httpGet.addHeader(BasicScheme.authenticate(
                        new UsernamePasswordCredentials(uname, password),
                        HTTP.UTF_8, false));

                HttpResponse httpResponse = httpClient.execute(httpGet);

                // Read the contents of an entity and return it as a String.
                content = EntityUtils.toString(httpResponse.getEntity());

                Log.e("content: ", "> " + content);





              //  listOfString.clear();



                InputStream inputStream = httpResponse.getEntity().getContent();
                bufferedReader = new BufferedReader(new InputStreamReader(
                        inputStream));

                String readLine = bufferedReader.readLine();
                while (readLine != null) {
                    stringBuffer.append(readLine);
                    stringBuffer.append("\n");
                    readLine = bufferedReader.readLine();
                }

            }  catch (Exception e) {
                // TODO: handle exception
            } finally {
                if (bufferedReader != null) {
                    try {
                        bufferedReader.close();
                    } catch (IOException e) {
                        // TODO: handle exception
                    }
                }
            }
            return false;
        }

        protected void onPostExecute(Boolean result) {

            txt1=(TextView)findViewById(R.id.txt1);
            txt2=(TextView)findViewById(R.id.txt2);
            txt3=(TextView)findViewById(R.id.txt3);
            txt4=(TextView)findViewById(R.id.txt4);
            txt5=(TextView)findViewById(R.id.txt5);
            txt6=(TextView)findViewById(R.id.txt6);
            txt7=(TextView)findViewById(R.id.txt7);
            txt8=(TextView)findViewById(R.id.txt8);

            Document doc = Jsoup.parse(content);
            htmlContentInStringFormat = doc.title();

            Elements td=doc.getElementsByTag("td");
            //Log.e("td: ", "> " + td);

            String td1=td.toString();
            //  Log.e("td1: ", "> " + td1);

            Elements articles = doc.select("td");

            for (Element element : articles) {
                String content1 = element.text();
                Log.e("content1: ", "> " + content1);
                listOfString.add(content1);
                System.out.println(content1);
            }

            t1 = listOfString.get(26);
            t2 = listOfString.get(31);
            t3 = listOfString.get(36);
            t4 = listOfString.get(41);
            t5 = listOfString.get(46);
            t6 = listOfString.get(51);
            t7 = listOfString.get(56);
            t8 = listOfString.get(61);

            Log.e("t1: ", "> " + t1);
            Log.e("t2: ", "> " + t2);
            Log.e("t3: ", "> " + t3);
            Log.e("t4: ", "> " + t4);
            txt1.setText(t1);
            txt2.setText(t2);
            txt3.setText(t3);
            txt4.setText(t4);
            txt5.setText(t5);
            txt6.setText(t6);
            txt7.setText(t7);
            txt8.setText(t8);

        }
    }
}

and it give me roor like this..

Answer 1

Application Not Responding (ANR) - will occur if we are doing any heavy functionality along with UI modification in the Main(UI) Thread. If time consuming heavy computation occurs in UI thread, it will delay response to user actions, which may irritate user, and hence stop your process. Android versions above 2.3.3(Gingerbread) in fact strictly discourages heavy processing in UI thread and allows user to close the app with ANR dialog.

Solution - Run only UI components in Main Thread and move other computation to background thread. In this case, move the parsing work to background thread and pass the parsed results to onPostExecute() call.

Note - In any situation in which your app performs a potentially lengthy operation, you should not perform the work on the UI thread, but instead create a worker thread and do most of the work there.