err log

[yuefeng007]

[ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: NoSuchMethodError: The setter 'onDisconnected=' was called on null. E/flutter ( 5787): Receiver: null E/flutter ( 5787): Tried calling: onDisconnected=Closure: () => void from Function 'internalDisconnect':.

[shamblett]

Which version of the client are you using? I'll need a full client log to see whats happening.

[yuefeng007]

您正在使用哪个版本的客户端？我需要完整的客户端日志以查看发生了什么。

client ： android mqtt_client: ^6.0.0

demo code： final MqttClient client = MqttClient('test.mosquitto.org', ''); client.onDisconnected = () { print('MQTT-->disconnected');}; client.onConnected = () {print('MQTT-->connecting');}; client.onSubscribed = (String topic) {print('MQTT-->onSubscribed ');} client.pongCallback = () { print('MQTT-->pong');}; await client.connect(); log： MQTT-->connecting E/flutter (18435): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: NoSuchMethodError: The setter 'onDisconnected=' was called on null. E/flutter (18435): Receiver: null E/flutter (18435): Tried calling: onDisconnected=Closure: () => void from Function 'internalDisconnect':. E/flutter (18435): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5) E/flutter (18435): #1 MqttClient.connect (package:mqtt_client/src/mqtt_client.dart:185:23) E/flutter (18435): #2 MqttManager.connect (package:appl/config/Mqtt.dart:55:25) E/flutter (18435): #3 new MqttManager._internal (package:appl/config/Mqtt.dart:39:5) E/flutter (18435): #4 MqttManager._getInstance (package:appl/config/Mqtt.dart:44:23) E/flutter (18435): #5 new MqttManager (package:appl/config/Mqtt.dart:12:28) E/flutter (18435): #6 _NoticePageState.build.<anonymous closure> (package:appl/modules/notice/notice_page.dart:77:21) E/flutter (18435): #7 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:706:14) E/flutter (18435): #8 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:789:36) E/flutter (18435): #9 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24) E/flutter (18435): #10 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:486:11) E/flutter (18435): #11 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:264:5) E/flutter (18435): #12 BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:199:7) E/flutter (18435): #13 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:467:9) E/flutter (18435): #14 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:76:12) E/flutter (18435): #15 PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:117:9) E/flutter (18435): #16 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:379:8) E/flutter (18435): #17 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:115:18) E/flutter (18435): #18 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:7) E/flutter (18435): #19 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:218:19) E/flutter (18435): #20 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:198:22) E/flutter (18435): #21 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:156:7) E/flutter (18435): #22 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:102:7) E/flutter (18435): #23 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:86:7) E/flutter (18435): #24 _rootRunUnary (dart:async/zone.dart:1138:13) E/flutter (18435): #25 _CustomZone.runUnary (dart:async/zone.dart:1031:19) E/flutter (18435): #26 _CustomZone.runUnaryGuarded (dart:async/zone.dart:933:7) E/flutter (18435): #27 _invoke1 (dart:ui/hooks.dart:273:10) E/flutter (18435): #28 _dispatchPointerDataPacket (dart:ui/hooks.dart:182:5)

[shamblett]

From version 6.0.0 of the client you can't use MqttClient you must use the client appropriate for your platform, in your case use MqttServerClient, please read the changelog.

[yuefeng007]

Thank you very much.