title: admob : changing ads
body: <p>I use following code to show ads in onCreate() of the activity
  Since my activity is displayed for longer times, can I refresh the ads ? or will it automatically refresh them ? Do I even need to change them or should not bother it ?</p>
  
  <pre><code>        //only ask for test ad, in emulator , should remove this later in real device
          AdRequest adRequest = new AdRequest();
          //adRequest.addTestDevice(AdRequest.TEST_EMULATOR);               // Emulator
          //adRequest.addTestDevice("TEST_DEVICE_ID");                
  
           // Create the adView
          adView = new AdView(this, AdSize.BANNER, "908908098098");
  
          // Lookup your LinearLayout assuming it’s been given
          // the attribute android:id="@+id/mainLayout"    
  
          LinearLayout layout = (LinearLayout)findViewById(R.id.adLayout);
  
          // Add the adView to it
          layout.addView(adView);
  
          // Initiate a generic request to load it with an ad
          adView.loadAd(adRequest);                   
  </code></pre>