Use Handler to send message to ProgressBar and update progress

<?xml version="1.0" encoding="utf-8"?>
<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>

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ProgressBar;
/*  w ww .j  ava  2s.  co m*/
public class MainActivity extends Activity {
  ProgressBar bar;
  Handler handler=new Handler() {
    @Override
    public void handleMessage(Message msg) {
      bar.incrementProgressBy(5);
    }
  };
  boolean isRunning=false;
  
  @Override
  public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.main);
    bar=(ProgressBar)findViewById(R.id.progress);
  }
  
  public void onStart() {
    super.onStart();
    bar.setProgress(0);
    
    Thread background=new Thread(new Runnable() {
      public void run() {
        try {
          for (int i=0;i<20 && isRunning;i++) {
            Thread.sleep(1000);
            handler.sendMessage(handler.obtainMessage());
          }
        }
        catch (Throwable t) {
          // just end the background thread
        }
      }
    });
    
    isRunning=true;
    background.start();
  }
  
  public void onStop() {
    super.onStop();
    isRunning=false;
  }
}