set ExpandableListView checkboxes checked when initializing

I am using this script for an expandable listview with checkboxes. http://ift.tt/2lA5Lqj

It works awesome, i also managed to get the specific checkboxes state to save in my shared preferences.

But now the problem is i want to load the checkboxes state when the activity is initializing. Like i saved the states of every checkbox in a shared preferences file. Now i want to load this SharedPreferences file and enable the checkboxes which should be enabled in this activity.

I know how to load the SharedPref file, and how to get data out of it. But how do i enable the checkboxes when initializing?