How to list through items in custom code?

Hi there,

I have a List View and each list item has a Radio Button widget to show 4 options for the user to choose. When the user clicks some button, I need to trigger a custom action. The custom action is basically to loop through each item within the list view, look at the Radio Button's select value, and do some business logic.

My main question is how I can access the List View and each item from the custom code.

FYI I looked at BuildContext parameter and it does not seem to be the way for me to get all the widgets I need.

If you know some documents, or URL out there explaining this, please let me know and I will be more than happy to look into it.

Thanks in advance.