How do I get the id of checked checkboxes from recyclerview?

I have a recyclearview with A few checkboxes. text and id of checkboxes received from the API. I should send id of checked checkboxes to API. now, I have two problems:

• how to get checked checkboxes ids and store in a String value? this the string must be used in the activity.
• when a user clicks to checkbox and this checked, id of checkbox save in String. now, User regrets and unchecked checkbox. in String, the id of checkbox should remove.

can you help me?