我正在尝试用颤振的图书馆火焰制作游戏。但我每次都收到这个错误。据说更新是在 null 上调用的。但是我已经在初始化函数中进行了初始化。我尝试了几种方法，但似乎没有任何效果。请帮我修复错误。
import 'dart:math';
import 'dart:ui';
import 'package:flame/flame.dart';
import 'package:flame/game.dart';
import 'package:flutter/cupertino.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:small_game/components/Enemy.dart';
import 'package:small_game/components/enemy_spawner.dart';
import 'package:small_game/components/heath_bar.dart';
import 'package:small_game/components/highscoreText.dart';
import 'package:small_game/components/player.dart';
import 'package:small_game/components/score_text.dart';
import 'package:small_game/components/startText.dart';
import 'package:small_game/states.dart' as gameState;
class GameController extends Game{
Random rand;
Size screenSize;
double tileSize;
Player player;
EnemySpawner enemySpawner;
List<Enemy> enemies;
HealthBar healthBar;
int score;
ScoreText scoreText;
SharedPreferences storage;
gameState.State state;
HighScoreText highScoreText;
StartText startText;
GameController(this.storage){
initialize();
}
void initialize() async{
rand = Random();
resize(await Flame.util.initialDimensions());
player = Player(this);
state = gameState.State.menu;
enemies = List<Enemy>();
enemySpawner = EnemySpawner(this);
healthBar = HealthBar(this);
score = 0;
highScoreText = HighScoreText(this);
startText = StartText(this);
}
@override
void render(Canvas canvas) {
Rect background = Rect.fromLTWH(0, 0, screenSize.width, screenSize.height);
Paint backgroundPaint = Paint()..color = Color(0xffFCFCFA);
canvas.drawRect(background, backgroundPaint);
player.render(canvas);
if(state == gameState.State.menu){
startText.render(canvas);
highScoreText.render(canvas);
} else if(state == gameState.State.playing) {
enemies.forEach((Enemy enemy) => enemy.render(canvas));
scoreText.render(canvas);
healthBar.render(canvas);
}
}
@override
void update(double t) {
if(state == gameState.State.menu){
highScoreText.update(t);
startText.update(t);
} else if(state == gameState.State.playing) {
enemies.forEach((Enemy enemy) => enemy.update(t));
enemies.removeWhere((Enemy enemy) => enemy.isDead);
player.update(t);
scoreText.update(t);
healthBar.update(t);
enemySpawner.update(t);
}
}
void resize(Size size){
screenSize = size;
tileSize = screenSize.width / 10;
}
void onTapDown(TapDownDetails d){
enemies.forEach((Enemy enemy) {
if(state == gameState.State.menu){
state = gameState.State.playing;
}
if(enemy.enemyRect.contains(d.globalPosition)){
enemy.onTapDown();
}
});
}
void spawnEnemies(){
double x,y;
switch(rand.nextInt(4)){
case 0:
//TOP
x = rand.nextDouble() * screenSize.width;
y = -tileSize * 2.5;
break;
case 1:
//RIGHT
x = (tileSize * 2.5) + screenSize.width;
y = rand.nextDouble() * screenSize.height;
break;
case 2:
//BOTTOM
x = rand.nextDouble() * screenSize.width;
y = (tileSize * 2.5) + screenSize.height;
break;
case 3:
//LEFT
x = -(tileSize * 2.5);
y = rand.nextDouble() * screenSize.height;
}
enemies.add(Enemy(this, x, y));
}
}
我的错误：
I/flutter (20131): ══╡ 调度程序库发现异常╞═════════════════════════␐════════════ ═══════════════════════ I/flutter（20131）：在调度程序回调期间引发以下 NoSuchMethodError：I/flutter（20131）：方法' update' 在 null 上被调用。I/flutter (20131): Receiver: null I/flutter (20131): 尝试调用: update(0.0) I/flutter (20131): I/flutter (20131): 当异常被抛出时，这是堆栈：I /颤动（20131）：#0
Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5) I/flutter (20131): #1 GameController.update (package:small_game/gameController.dart:69:17) I/flutter (20131): #2 GameRenderBox._update (package:flame/game.dart:360:10) I/flutter (20131): #3 GameRenderBox._tick (package:flame/game.dart:353:5) I/flutter (20131): #4 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1033:15) I/flutter (20131): #5 SchedulerBinding.handleBeginFrame。(package:flutter/src/scheduler/binding.dart:951:11) I/flutter (20131): #6 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8) I/flutter (20131) : #7 SchedulerBinding.handleBeginFrame (package:flutter/src/scheduler/binding.dart:949:17) I/flutter (20131): #8 SchedulerBinding.scheduleWarmUpFrame。(package:flutter/src/scheduler/binding.dart:780:7) I/flutter (20131): #17 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:382:19) I/flutter (20131) : #18 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:416:5) I/flutter (20131): #19 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:172:12) I/ flutter (20131): (从包 dart:async 和包 dart:async-patch 中省略了 8 帧) I/flutter (20131): I/flutter (20131): I/flutter (20131): 在上下文中抛出了这个异常调度程序回调。当调度程序回调是 19) I/flutter (20131): #18 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:416:5) I/flutter (20131): #19 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch. dart:172:12) I/flutter (20131): (从包 dart:async 和包 dart:async-patch 中省略了 8 帧) I/flutter (20131): I/flutter (20131): I/flutter (20131) ：此异常是在调度程序回调的上下文中引发的。当调度程序回调是 19) I/flutter (20131): #18 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:416:5) I/flutter (20131): #19 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch. dart:172:12) I/flutter (20131): (从包 dart:async 和包 dart:async-patch 中省略了 8 帧) I/flutter (20131): I/flutter (20131): I/flutter (20131) ：此异常是在调度程序回调的上下文中引发的。当调度程序回调是 I/flutter (20131)：此异常是在调度程序回调的上下文中引发的。当调度程序回调是 I/flutter (20131)：此异常是在调度程序回调的上下文中引发的。当调度程序回调是挂号的（与抛出异常时相反），这是堆栈：I/flutter (20131): #0 new _FrameCallbackEntry。(package:flutter/src/scheduler/binding.dart:112:33) I/flutter (20131): #1 new _FrameCallbackEntry (package:flutter/src/scheduler/binding.dart:115:6) I/flutter (20131 ): #2 SchedulerBinding.scheduleFrameCallback (package:flutter/src/scheduler/binding.dart:459:49) I/flutter (20131): #3 GameRenderBox._scheduleTick (package:flame/game.dart:341:50) I /flutter (20131): #4 GameRenderBox.attach (package:flame/game.dart:328:5) I/flutter (20131): #5 RenderObjectWithChildMixin.attach (package:flutter/src/rendering/object.dart:2886 :14) I/flutter (20131): #6 AbstractNode.adoptChild (package:flutter/src/foundation/node.dart:132:13) I/flutter (20131): 5) I/flutter (20131)：#22 RenderObjectToWidgetAdapter.attachToRenderTree。(package:flutter/src/widgets/binding.dart:915:17) I/flutter (20131): #23 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2328:19) I/flutter ( 20131): #24 RenderObjectToWidgetAdapter.attachToRenderTree (package:flutter/src/widgets/binding.dart:914:13) I/flutter (20131): #25 WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart: 795:7) I/flutter (20131): #26 runApp (package:flutter/src/widgets/binding.dart:845:7) I/flutter (20131): #27 main (package:small_game/main.dart: 17:3）I/flutter（20131）：（从包 dart:async 和包 dart:async-patch 中删除了 14 帧）