<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <ProgressBar android:id="@+id/progress"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

/**
 * @author mSeguy
 * @goals This class aims to show how to use handler and thread
 */
public class HandlerTuto extends Activity {
    /**     * The progress bar to update     */
    ProgressBar bar;
    /**     * The progress bar increment stored in the bundle of the handler's message     */
    private final String PROGRESS_BAR_INCREMENT="ProgreesBarIncrementId";
    /**     * The handler that manage the communication from external threads to Gui's thread     */
    Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            int progress=msg.getData().getInt(PROGRESS_BAR_INCREMENT);
            // here, just increment the progress bar
            bar.incrementProgressBy(progress);
            // You can do quick stuff that update the Gui
            
        }
    };
    /**     * An atomic boolean to manage the external thread's destruction     */
    AtomicBoolean isRunning = new AtomicBoolean(false);
    /**     * An atomic boolean to manage the external thread's pausing     */
    AtomicBoolean isPausing = new AtomicBoolean(false);

    // Create the activity
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.main);
        // Define the progress bar
        bar = (ProgressBar) findViewById(R.id.progress);
        bar.setMax(210);
    }

    /** Called method when launching the activity */
    public void onStart() {
        super.onStart();
        // initialize the progress bar
        bar.setProgress(0);
        // Thread definition, it could have been done in an external classes
        Thread background = new Thread(new Runnable() {
            /**
             * The bundle exchanged within the message between the tread and the handler
             */
            Bundle messageBundle=new Bundle();
            /**
             * The message exchanged between this thread and the handler
             */
            Message myMessage;
            // Overriden Run method
            public void run() {
                try {
                    // If isRunning is false, the run method will end
                    for (int i = 0; i < 20 && isRunning.get(); i++) {
                        // while on Pause but still alive
                        while (isPausing.get() && (isRunning.get())) {
                            // Make a pause
                            Thread.sleep(1000);
                        }
                        // Sleep one second
                        Thread.sleep(1000);
                        // Send the message to the handler (the handler.obtainMessage is more
                        // efficient that creating a message from scratch)
                        //create a message, the best way is to use that method:
                        myMessage=handler.obtainMessage();    
                        //then, if you want add data to your message (you could use arg0 and arg1 too)
                        messageBundle.putInt(PROGRESS_BAR_INCREMENT, i);
                        myMessage.setData(messageBundle);
                        //then send the message
                        handler.sendMessage(myMessage);
                    }
                } catch (Throwable t) {
                    // just end the background thread
                }
            }
        });
        //Initialize the threadSafe booleans
        isRunning.set(true);
        isPausing.set(false);
        //And launch the thread
        background.start();
    }
    
 /************************************************************************************/
/** Managing life cycle *****************************************************************/ 
/**************************************************************************************/
    //Method called when activity stop
    public void onStop() {
        super.onStop();
        //Update the boolean to kill the thread
        isRunning.set(false);
    }

    /* (non-Javadoc) 
     * @see android.app.Activity#onPause()
     */
    @Override
    protected void onPause() {
        super.onPause();
        //Update the boolean to pause the thread
        isPausing.set(true);
    }

    /* (non-Javadoc)
     * @see android.app.Activity#onResume()
     */
    @Override
    protected void onResume() {
        super.onResume();
        //Update the boolean to resume the thread
        isPausing.set(false);
    }

}