This question may sound stupid but I wana know When do we put activity name in Intent.putExtra()? In one case we are putting extra only with bundle and in other
I think you mean putExtra(String, Bundle) vs putExtras(Bundle) (with s).
The first adds the bundle as the value for the key you provide. The bundle is simple an object value.
The second adds all the key/value pairs from the provided bundle to the intent. In this case the content of the bundle will be added to the intent, not the bundle itself.
Think of them as in Map interface:
Map.put(String key, Object value)
vs
Map.putAll(Map anotherMap)