Question

i want to change a component value in thread.
we did it at c# with invoke.
how could do i do it in android?

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;

public class procActivity extends Activity {
    /** Called when the activity is first created. */
    String H ="";

    EditText et;

    public void onCreate(Bundle savedInstanceState)  
    { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.main);

        et = (EditText) findViewById(R.id.etDetail);

        String result = "";

        et.setText(
                "             Process Manager :         \n"
            +   "****************************\n"
            +   "PID      Name      Process Usage    \n"
            +   result
                );

        showResult sohwresult = new showResult();
        sohwresult = (showResult) new showResult().execute("");

    }

        class showResult extends AsyncTask<String, Integer, String> 
        {
        // Called to initiate the background activity
        @Override
        protected String doInBackground(String... statuses) 
        { 
        while(true)
          try 
          {
            String result1 = "";

            H=(
                    "             Process Manager :         \n"
                +   "****************************\n"
                +   "PID      Name      Process Usage    \n"
                +   result1
                    );
       ******               et.setText(H); //// it s where i want to do it!************

          } 
          catch (Exception e) 
          {
              break;
          }
            return "";
        }

        // Called when there's a status to be updated
        @Override
        protected void onProgressUpdate(Integer... values) 
        { 
          super.onProgressUpdate(values);
        }

        // Called once the background activity has completed
        @Override
        protected void onPostExecute(String result) 
        { 

        }
    }
}

Answer 1

You cannot change UI from non-UI threads. In your case your can:

protected String doInBackground(String... statuses) 
{
    //... 
    H = ...;
    return H;
}

@Override
protected void onPostExecute(String result) 
{ 
   et.setText(H);
}

That’s because onPostExecute will be called in UI-thread and therefore it can change state of UI components. For more details see AsyncTask documentation.