复制 privatevoidinitLoadingUnitMappingToComponentNames(){String mappingKey=DeferredComponentManager.class.getName()+".loadingUnitMapping";ApplicationInfo applicationInfo=getApplicationInfo();if(applicationInfo!=null){Bundle metaData=applicationInfo.metaData;if(metaData!=null){String rawMappingString=metaData.getStr...
super class’s no-arg constructor(父类无参数构造函数) main class’s no-arg constructor (主类无参数构造函数) 如果父类不显示提供无名无参数构造函数的构造函数,在子类中必须手打调用父类的一个构造函数。这种情况下,调用父类的构造函数的代码放在子类构造函数名后,子类构造函数体前,中间使用:(colon) 分割。
{ return false; } } } void main() { // instantiate the class by using its constructor, passing in the expected parameters // we defined already Car tesla = Car('Model S', 50000, true); // returns true by using the Car class's method, isExpensive, because tesla.price = 50,000 ...
StringmappingKey = DeferredComponentManager.class.getName() +".loadingUnitMapping"; ApplicationInfo applicationInfo = getApplicationInfo(); if(applicationInfo !=null) { Bundle metaData = applicationInfo.metaData; if(metaData !=null) { StringrawMappingString = metaData.getString(MAPPING_KEY,null); if(r...
classWidgetsFlutterBinding extends BindingBase with GestureBinding,SchedulerBinding,ServicesBinding,PaintingBinding,SemanticsBinding,RendererBinding,WidgetsBinding 手势相关的是GestureBinding,我们来看看它的initInstances()初始化的实现: @overridevoidinitInstances(){super.initInstances();_instance=this;platformDispatcher.on...
Used to annotate a class, mixin, or extension declarationC. Indicates that any type arguments declared onCare to be treated as optional. Tools such as the analyzer and linter can use this information to suppress warnings that would otherwise require type arguments onCto be provided.const _Optiona...
If you want a more in-depth guide of how to get a Flutter app running on a real device or emulator, check ourlearn-fluttertutorial. We will get you sorted in no time! If you open the app, you should be able to see the following. ...
If we want to create a provider for this class, we can do this: final counterProvider = NotifierProvider<Counter, int>(() { return Counter(); }); Alternatively, we can use Counter.new as a constructor tear-off: final counterProvider = NotifierProvider<Counter, int>(Counter.new); ...
基本上，Singleton类意味着只能创建该Class的一个示例，因此它获得了名称Singleton。Singleton类只有一个自身...
classHelloWorldWidgetextendsStatelessWidget{@overrideWidgetbuild(BuildContext context){returnText(/* how to read the provider value here? */, ); } } 所有Flutter小部件都有一个BuildContext对象,我们可以使用它来访问小部件树内的内容(例如Theme.of(context))。