How to pass a variable (TextEditingController) to another class - flutter

Question

class that i have the variable in
...
class _ActivitiesParticipantsState extends State<ActivitiesParticipants> {
final activityController = TextEditingController();
final user = FirebaseAuth.instance.currentUser!;
//Activities participants
List<String> docIDs = [];
//get docIDS
Future getDocId() async {
await FirebaseFirestore.instance
.collection(
activityController.text.trim(),
)
.get()
.then(
(snapshot) => snapshot.docs.forEach(
(element) {
docIDs.add(element.reference.id);
},
),
);
//stuff
}
#override
void dispose() {
activityController.dispose();
super.dispose();
}
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Padding(
padding: const EdgeInsets.symmetric(vertical: 30, horizontal: 10),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
TextFormField(
controller: activityController,
decoration: InputDecoration(
labelText: 'e',
border: InputBorder.none,
),
),
GestureDetector(
onTap: () async {
setState(
() {
getDocId();
},
);
},
child: Container(
padding: EdgeInsets.all(
20,
),
decoration: BoxDecoration(
color: Colors.deepPurple,
borderRadius: BorderRadius.circular(12),
),
child: Center(
child: Text(
'Test',
style: TextStyle(
color: Colors.white,
fontFamily: 'Quicksand',
fontWeight: FontWeight.w600,
fontSize: 18,
),
),
),
),
),
Expanded(
child: FutureBuilder(
builder: (context, snapshot) {
return ListView.builder(
itemCount: wee(),
//docIDs.length,
itemBuilder: (context, index) {
return Padding(
padding: const EdgeInsets.symmetric(vertical: 15),
child: ListTile(
dense: true,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8)),
tileColor: Color.fromARGB(255, 235, 235, 235),
title: Padding(
padding: const EdgeInsets.symmetric(
horizontal: 10, vertical: 20),
child: Column(
children: [
SizedBox(
height: 5,
),
Align(
alignment: Alignment.centerLeft,
child: Title(
color: Colors.black,
child: InterestedName(
documentID: docIDs[index]),
),
),
SizedBox(
height: 20,
),
],
),
),
),
);
},
);
},
),
),
],
),
),
),
);
}
}
...
How do I get the variable "activityController" to another class?
This other class is used to get Text to fill the ListTile
class that I want to get the variable
final String documentID;
InterestedName({required this.documentID});
#override
Widget build(BuildContext context) {
// get the collection
CollectionReference users = FirebaseFirestore.instance.collection('Project Koalas [test]');
return FutureBuilder<DocumentSnapshot>(
future: users.doc(documentID).get(),
builder: ((context, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
Map<String, dynamic> data =
snapshot.data!.data() as Map<String, dynamic>;
return Text(
'Name: ${data['name']}',
style: TextStyle(
fontSize: 16,
fontFamily: 'Quicksand',
fontWeight: FontWeight.w600),
);
}
return Text('loading...');
}),
);
}
}
I would like to get the variable to be able to get the collection name that I want to take data from, as the collection I would like to take from is dependent on the user's choice.
If there is any way else to somehow fill the List tile in the same class, please let me know how.
Any help appreciated!