如何在自定义对话框中验证复选框？

I am trying to make a custom dialog with a set of check boxes, and I want to validate them so that if the user clicks the ok button without selecting any one of them, a message will be displayed to the user asking them to select at least one choice. If they have (selected a t least one choice) a message will displayed saying which check boxes that the user has checked.I am trying to make a custom dialog with a set