public DrawerBuilder withRootView(@IdRes int rootViewRes) {
        if (mActivity == null) {
            throw new RuntimeException("please pass an activity first to use this call");
        }

        return withRootView((ViewGroup) mActivity.findViewById(rootViewRes));
    }
public DrawerBuilder withRootView ( @ IdRes int rootViewRes ) { if ( mActivity == null ) { throw new RuntimeException ( "please pass an activity first to use this call" ) ; } return withRootView ( ( ViewGroup ) mActivity . findViewById ( rootViewRes ) ) ; }
Sets the rootView which will host the DrawerLayout
The content of this view will be extracted and added as the new content inside the drawerLayout

@param rootViewRes the id of a view which will get switched out by the DrawerLayout and added as its child