I am **using same environment** as you described and working fine. Dinesh give a try:

 

    Set<String> contextNames = ad.getContextHandles();	    
    					   System.out.println("Context Names:"+contextNames.toString());
    
    					   String lastestContextView = (String) contextNames.toArray()[contextNames.size()-1];
    
    					   if (lastestContextView.contains("WEBVIEW_"))
    					   {
    						   ad.context(lastestContextView);
    						   System.out.println("Latest Context Name"+lastestContextView);
    					   }					
    					Thread.sleep(5000);
    					ad.context("NATIVE_APP");