Saeid Saeid - 4 months ago 7
Android Question

how to download text from web in android?

I am new to android and don't know much. I need help to change this code - I want to download some text from a website.

If I use the code:
new DownloadTextTask().execute("http://www.test.com/file.xml");

It doesnt show the downloaded text in

TextView
, but if I reopen the app I can see the text. I think its because it's asynchronous, and it has delay to download text.

How can I fix this, or just use this code instead:
(I mean using
DownloadText()
function directly! It didnt work when I tried!)

TextView txt = (TextView)findViewById(R.id.textTest);
txt.setText(DownloadText("http://www.test.com/"));


All the code:

public class MainActivity extends AppCompatActivity {
public InputStream OpenHttpConnection(String urlString) throws IOException{
InputStream in = null;
int response = -1;
URL url = new URL(urlString);
URLConnection conn = url.openConnection();
if (!(conn instanceof HttpURLConnection))
throw new IOException("Not an HTTP connection");
try{
HttpURLConnection httpConn = (HttpURLConnection) conn;
httpConn.setAllowUserInteraction(false);
httpConn.setInstanceFollowRedirects(true);
httpConn.setRequestMethod("GET");
httpConn.connect();
response = httpConn.getResponseCode();
if (response == HttpURLConnection.HTTP_OK) {
in = httpConn.getInputStream();
}
}
catch (Exception ex)
{
Log.d("MainActivity", ex.getLocalizedMessage());
throw new IOException("Error connecting");
}
return in;
}

public String DownloadText(String URL)
{
int BUFFER_SIZE = 2000;
InputStream in = null;
try {
in = OpenHttpConnection(URL);
} catch (IOException e) {
Log.d("MainActivity", e.getLocalizedMessage());
return "";
}
InputStreamReader isr = new InputStreamReader(in);
int charRead;
String str = "";
char[] inputBuffer = new char[BUFFER_SIZE];
try {
while ((charRead = isr.read(inputBuffer))>0) {
//---convert the chars to a String---
String readString =
String.copyValueOf(inputBuffer, 0, charRead);
str += readString;
inputBuffer = new char[BUFFER_SIZE];
}
in.close();
} catch (IOException e) {
Log.d("MainActivity", e.getLocalizedMessage());
return "";
}
return str;
}

private class DownloadTextTask extends AsyncTask<String, Void, String> {

protected String doInBackground(String... urls) {
return DownloadText(urls[0]);
}
@Override
protected void onPostExecute(String result) {
Toast.makeText(getBaseContext(), result, Toast.LENGTH_LONG).show();

}

}

public static class xmlClass
{
public static String xml ="";
}



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

//new DownloadTextTask().execute("http://www.test.com/file.xml");

TextView txt = (TextView)findViewById(R.id.textTest);
txt.setText(DownloadText("http://www.test.com/file.xml"));

}
}

Answer

Make a callback from AsyncTask as follows

private class DownloadTextTask extends AsyncTask {
 MainActivity instance=null;
   public DownloadTextTask(MainActivity instance){
      this.instance=instance;
   }


    protected String doInBackground(String... urls) {
        return DownloadText(urls[0]);
    }
    @Override
    protected void onPostExecute(String result) {
        Toast.makeText(getBaseContext(), result, Toast.LENGTH_LONG).show();
      if(instance!=null){
           instance.callback(result);
       }

    }

}

and add a method named callback in MainActivity

public class MainActivity extends AppCompatActivity {
.... your code......
  public void callback(String result){
   txt.setText(Parse your response);
  }
}

You need to make a call as follows from mainactivity

new DownloadTextTask(this).execute("http://www.test.com/file.xml");
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