Android : Get the current fragment in Android

I'm using NavigationDrawer Activity (predefined view in AndroidStudio) and I need to put (and get) the current fragment to switch between fragments.

I saw in some places to put visible and hidden the fragments but I have more than 3 so I need to identify all the fragments before switch between thems.

How can I solved? I just only find to set Tags at the moment to be displayed or set the visibility.

Thanks.