TextView real time update AsyncTask

Question

I'm making an android application that downloads some text from a web page and puts it in a String, then it prints the string in a TextView. But the content of the web page can change every seconds, so i want TextView to update in real-time, showing the new String every seconds. To download text from the webpage and set TextView's text I used AsyncTask, and i called the execute() in onCreate() method, in main Activity. I don't know how update it, without make application crashed. Sorry for bad English, that's my MainActivity:

   package com.example.pack;

    import java.net.MalformedURLException;
    import java.net.URL;
    import android.app.Activity;
    import android.os.Bundle;
    import android.widget.TextView;

    public class MainActivity extends Activity
    {
    TextView textView;
    URL url;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        url = null;

        try
        {
            url = new URL("myURL");
        }

        catch (MalformedURLException e) {}

        new VariabileLikeTask(textView).execute(url);
    }
    }

And that's my aSyncTask:

package com.example.pack;

import android.os.AsyncTask;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;

public class VariabileLikeTask extends AsyncTask<URL, Void, CharSequence>
{
    TextView textView;

    public VariabileLikeTask(TextView textView)
    {
        this.textView = textView;
    }

    @Override
    protected String doInBackground(URL... urls)
    {
        URL url = urls[0];
        InputStream in = null;
        int risposta = -1;
        String text = "";

        try
        {
            URLConnection conn = url.openConnection();

            if (!(conn instanceof HttpURLConnection))
              throw new IOException("No connection");

            HttpURLConnection httpConn = (HttpURLConnection) conn;
            httpConn.setAllowUserInteraction(false);
            httpConn.setInstanceFollowRedirects(true);
            httpConn.setRequestMethod("GET");
            httpConn.connect();

            risposta = httpConn.getResponseCode();

            if (risposta == HttpURLConnection.HTTP_OK)
                in = httpConn.getInputStream();

            BufferedReader bf = new BufferedReader(new InputStreamReader(in));
            text = bf.readLine();

            in.close();
            bf.close();

        }
        catch (Exception ex) {}

        return text;
    }

    @Override
    protected void onPostExecute(CharSequence text)
    {
        textView.setText(text);
    }
}

Sorry if the format code is wrong, this is my first thread.

score 0 · Answer 1 · answered Jul 06 '15 at 14:15

Isn't it a bad idea to run the AsyncTask frequently? This will make the app heavier in network operations.

If you mean the word real-time push notification or socket connection would be the best match. If you can't use a push notification because you are trying to fetch data from a Web page consider using a service class. Then simply make a timer task and run the AsyncTask after a small interval of time.

Here a simple demo of running the task after an interval of time,

    private int m_interval = 5000; // 5 seconds by default, can be changed later
    private Handle m_handler;

    @Override
    protected void onCreate(Bundle bundle)
    {
      ...
      m_handler = new Handler();
    }

    Runnable m_statusChecker = new Runnable()
    {
         @Override 
         public void run() {
              //this function can change value of m_interval.
              new VariabileLikeTask(textView).execute(url); 
              m_handler.postDelayed(m_statusChecker, m_interval);
         }
    }

    void startRepeatingTask()
    {
        m_statusChecker.run(); 
    }

    void stopRepeatingTask()
    {
        m_handler.removeCallback(m_statusChecker);
    }

score 0 · Answer 2 · edited May 23 '17 at 12:06

0

In this post the user try to show dialog from AsyncTask, but the code it's the same to change txtBox in runtime, watch it!

Tell me if I helped you and good programming!

edited May 23 '17 at 12:06

Community

1
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answered Jul 06 '15 at 14:18

Merlí Escarpenter Pérez

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TextView real time update AsyncTask

2 Answers2