main.xml ( activities defined GUI in xml)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:orientation="vertical" >

<ProgressBar android:id="@+id/progressbar"
 	        android:layout_width="wrap_content" 
 	        android:layout_height="wrap_content"
 	        style="@android:style/Widget.ProgressBar.Horizontal" />   sets up as Horizontal style

</LinearLayout>

BasicViews2Activity.java

package net.learn2develop.BasicViews2;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.ProgressBar;

public class BasicViews2Activity extends Activity {
 	   static int progress;
 	   ProgressBar progressBar;
 	   int progressStatus = 0;   //represents progress status, initialize to 0
 	   Handler handler = new Handler();  //handler for

 /** Called when the activity is first created. */
 	   @Override
 	   public void onCreate(Bundle savedInstanceState) {
 	        super.onCreate(savedInstanceState);  //START THE PROGRESS BAR
 	        setContentView(R.layout.main);
   
 	        progress = 0;
 	        progressBar = (ProgressBar) findViewById(R.id.progressbar);  //grab handle to GUI ProgressBar in xml file
 	        progressBar.setMax(200);
   
 	        //---do some work in background thread-----this is where we will do work and update progress bar
             //   do the work as a separate Thread whe will with start() method invocation below start running

 	        new Thread(new Runnable()          //IN YELLOW showing the anonymous instance of Runnable class createing here
 	        {
 	          public void run()
 	         {
 	            //—-do some work here—-
 	            while (progressStatus < 100)
 	            {
         	        progressStatus = doSomeWork();

                     //—-Update the progress bar—-
         	        handler.post(new Runnable()
            	            {
 	                       public void run() {
 	                            progressBar.setProgress(progressStatus); //update ProgressBar
 	                        }
 	                 });
 	            }

                 //---hides the progress bar---
     	        handler.post(new Runnable()
 	                {
 	                    public void run()
 	                    {
 	                        //---0 - VISIBLE; 4 - INVISIBLE; 8 - GONE---
 	                        progressBar.setVisibility(View.GONE);  //stop ProgressBar by hiding it
 	                    }
 	             });
 	         }

 
              //---do some long running work here---
 	         private int doSomeWork() 
 	         {
 	            try {
 	                //---simulate doing some work---
 	                Thread.sleep(50);
 	            } catch (InterruptedException e)
 	            {
 	                e.printStackTrace();
 	            }
 	   
                 return ++progress;
 	         }
         }).start();
 	       
     }
  }