Make one contact toggle with timer

This demonstrates that the state of the contacts in the UI can be
changed at runtime.

1 files changed, 29 insertions, 8 deletions

diff --git a/lib/main.dart b/lib/main.dart
index db8fcd2..b4cae3a 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 
 void main() {
@@ -17,9 +19,9 @@ class MainApp extends StatelessWidget {
 
 class Contact {
   final String address;
-  final bool isOpen;
+  bool isOpen;
 
-  const Contact({required this.address, required this.isOpen});
+  Contact({required this.address, required this.isOpen});
 }
 
 class ContactList extends StatefulWidget {
@@ -30,13 +32,32 @@ class ContactList extends StatefulWidget {
 }
 
 class _ContactListState extends State<ContactList> {
+  late final List<Contact> contacts;
+  Timer? _timer;
+
+  @override
+  void initState() {
+    super.initState();
+
+    contacts = <Contact>[
+      Contact(address: "Living Room Window", isOpen: false),
+      Contact(address: "Front Door", isOpen: true),
+      Contact(address: "Back Door", isOpen: false),
+      Contact(address: "Garage Window", isOpen: true),
+    ];
 
-  final List<Contact> contacts = const <Contact>[
-    Contact(address: "Living Room Window", isOpen: false),
-    Contact(address: "Front Door", isOpen: true),
-    Contact(address: "Back Door", isOpen: false),
-    Contact(address: "Garage Window", isOpen: true),
-  ];
+    _timer = Timer.periodic(const Duration(seconds: 1), (_) {
+      setState(() {
+        contacts[0].isOpen = !contacts[0].isOpen;
+      });
+    });
+  }
+
+  @override
+  void dispose() {
+    _timer?.cancel();
+    super.dispose();
+  }
 
   @override
   Widget build(BuildContext context) {