android - calling ui thread from worker thread

Question

Hi I want to make Toast available to me no-matter-what and available from any thread whenever I like within my application. So to do this I extended the Activity class:

import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.widget.Toast;  public class MyActivity extends Activity{     private Handler mHandler;      @Override        public void onCreate(Bundle savedInstanceState) {                mHandler = new Handler();         super.onCreate(savedInstanceState);     }      private class ToastRunnable implements Runnable {         String mText;          public ToastRunnable(String text) {             mText = text;         }          public void run(){            Toast.makeText(getApplicationContext(), mText, Toast.LENGTH_SHORT).show();         }     }      public void doToast(String msg) {         mHandler.post(new ToastRunnable(msg));     } } 

so that all Activity classes in my app are now simply

public class AppMain extends MyActivity {    //blah } 

what I expected to be able to do (in a worker thread) was this:

try{    MyActivity me = (MyActivity) Looper.getMainLooper().getThread();    me.doToast("Hello World"); } catch (Exception ex){    Log.e("oh dear", ex.getMessage()); } 

and so long as the Activity was a "MyActivity" it should work - but the problem is ---> the Looper.getMainLooper().getThread(); isn't returning the MyActivity to me and it's making me cry - what am I doing wrong?

: EDIT :

some background to explain "why" I am stuck with this type of implmentation.

I need to be able to confirm to the user that a "HTTP POST" event has been a success. Now. If the User clicks "OK" on the UI Form it MAY or MAY NOT have internet at that time.. If it has Internet - all well and good - it posts the form via HTTP POST all well and good.. but if there is NO Internet most (99.999% of Android apps lame /pathetic / mewling at this, and basically offer the user no plan "b" assuming that at all times the internet is there - when it is NOT)

My App will not "go lame (as I call it)" - it does have a plan "b" instead it "Queues" the post event and retries every x minutes.. now this is a silent thread in the background.. I have plenty of user interaction all over the app I don't know where the user will "be" but eventually when the HTTP POST that queue/retries/queue/retries returns "! Success! " I want to Toast that as a message to the user (EG: "your form was sent")

Answer 1

What's wrong with runOnUiThread?

http://developer.android.com/reference/android/app/Activity.html#runOnUiThread(java.lang.Runnable)

activity.runOnUiThread(new Runnable() {     public void run() {         Toast.makeText(activity, "Hello, world!", Toast.LENGTH_SHORT).show();     } });