singleton

问题 I'm working on a soundboard app, that has several pages of buttons to play sound effects with a stop button on every page should the user wish to manually interrupt the clip. I'm using avaudioplayer in each view to play the sound upon pressing the button for that clip. It works fine until the view is changed. If a user jumps to a new page the sound keeps playing and the stop button stops working even if they return to the original view. Pressing a sound button no longer interrupts the running

问题 I'm working on a soundboard app, that has several pages of buttons to play sound effects with a stop button on every page should the user wish to manually interrupt the clip. I'm using avaudioplayer in each view to play the sound upon pressing the button for that clip. It works fine until the view is changed. If a user jumps to a new page the sound keeps playing and the stop button stops working even if they return to the original view. Pressing a sound button no longer interrupts the running

问题 I'm reading wiki about the singleton pattern and I'm not sure if I understand this: https://en.wikipedia.org/wiki/Initialization-on-demand_holder_idiom part of it correctly. So to make it simple: Why is Bill Pugh's solution better than the example above? Is it because a static class is not load by the VM before it's actually used or something like this, so we don't create the object before we turn to the getInstance() method? Also is that method thread safe only to the extent of initializing

问题 I am converting a singleton to a Spring bean, so that if the singleton fails to initialize, then entire web application's spring context doesn't load properly. The advantage of making the Spring context not load properly, is that people will take notice and fix the configuration during deployment itself. As opposed to using 'non-spring bean' singleton: when that throws exception during initialization, nobody notices.. until a actual user complains of missing functionality. My changes are

问题 I am converting a singleton to a Spring bean, so that if the singleton fails to initialize, then entire web application's spring context doesn't load properly. The advantage of making the Spring context not load properly, is that people will take notice and fix the configuration during deployment itself. As opposed to using 'non-spring bean' singleton: when that throws exception during initialization, nobody notices.. until a actual user complains of missing functionality. My changes are

问题 What is wrong with this implementation in header file? template <typename T> class Singleton { public: static T* getInstance() { if (m_instance == NULL) { m_instance = new T(); } return m_instance; } private: static T* m_instance; }; I use it like this: typedef Singleton<MyClass> MyClassSingleton; I get linker error: error LNK2001: unresolved external symbol "private: static class MyClass * Singleton<class MyClass>::m_instance" (?m_instance@?$Singleton@VMyClass@@@@0PAVMyClass@@A) When I add

问题 I am wondering what the correct way is to make a copy of an object defined in the app delegate or a singleton object. In short, I am making an app which requires a user to login. This login view is just a modal view controller on top of the 'real' app, which consists of a tabbarcontroller, plus some tableview controllers. After a successful login, there is send a data request to a remote server, and the modal view controller is dismissed, revealing the tabbar controller and table views

问题 I am running into a strange problem. I have an interface, whose implementations tend to be stateless. So, I want them to be singletons. I get the implementation class names as strings. For example String clazz = "com.foo.Bar"; I have a rules factory to obtain instances of IRule implementations. public class RulesFactory { private static final Logger logger = LoggerFactory.getLogger(RulesFactory.class); @SuppressWarnings("unchecked") public static <T extends IRule> T getRuleInstance(String

问题 I'm trying to use a singleton (PhotoStorage) to provide an arrayList of Photo objects, but it seems that the PhotoStorage instance is not behaving as a singleton (two instances). I am using dagger to inject this singleton into a class named PhotoInteractor. The objectGraph seems A-OK up to this point. The same PhotoInteractor instance is used in three fragments in a viewpager. These fragments are all instantiated at runtime: RecentFragment: HistoryFragment: Notice how the instance @4067 of

问题 I'm using PDT and Aptana on Eclipse Indigo with PHP 5.3 and I want to create a singleton in a class. By singleton, I mean I want to just have one instance of that object, and for other objects or classes to get that single instance via a function that returns that object (so this would mean I'm trying to create an object within the class that defines that object, ie: creating objA within the class objA) I understand you can't just go a head and do this: public $object = new Object(); with in