singleton

问题 I'm an android app developer and a beginner in swift. I'm trying to implement a singleton class whose data members are shared throughout the app (like Settings). Getting this done in android is pretty simple but I'm breaking my head to do it in swift. Below is the code I've tried .. public class DataSet { public var notificationOnOff: Bool! public var interval: Int! public var alert: String! init() { self.notificationOnOff = true self.interval = 1; self.alert = nil; } init (onOff: Bool) {

问题 I am a newbie to Android and currently learning the Android SDK. I am writing a very simple application that will just play various sounds upon interacting with widgets. I am using MediaPlayer to playback the sounds. My question is should i use singleton pattern for MediaPlayer? I want just one object of MediaPlayer to be shared, but the confusion comes from the following link https://developer.android.com/reference/android/media/MediaPlayer.html which says that: It is also recommended that

问题 I'm creating an app where I need to pass relatively complex classes between several Activity s and Service s. Lets say something like this: public class A implements Serializable{ int myInt; String myString; B myB; } public class B implements Serializable{ ArrayList<String> myStrings; } Now this can be done by Intent.putExtra(String, Serializable) , but I could also create a singleton class holding the A instance. Using a singleton provides easy access to my instance of A , but it seems a bit

问题 In testing, it would be convenient to have a simple singleton data model that acts like an array. That is, if I have a singleton class called MySingletonClass that supports a sharedInstance variable you should be able to change an element in the array with subscripts: MySingletonClass.sharedInstance[ 0 ] = "New item 0" Also, when the app opens, it would be great if a simple assignment allowed the system to provide initial values to the array: MySingletonClass.sharedInstance = ["Item 0", "Item

问题 I made some changes per suggestions from another question to turn my class into a @Singleton rather than @Stateless , however I'm no longer receiving messages in my @MessageDriven Bean as I was before. Suggestions? Note that the topic is correctly defined in jbossmq-destinations-service.xml @javax.ejb.Singleton(mappedName="MySingletonClass") public class MySingletonClass implements SomeInterface { private Timer timer = null; @javax.annotation.Resource TimerService timerService; /** * Creates

问题 Using the lazy_static library to create a singleton. I am unable to access that singleton in a module in another file. If the module is defined below the main function I can access it fine. Given a main file such as the following, test_stuff can access gamedata fine: extern crate gamedata; #[macro_use] extern crate lazy_static; lazy_static! { pub static ref GAMEDATA: &'static str = "I am a test STrings"; } fn main() { println!("Game Data:{}",*GAMEDATA); let obj = gamedata::readinginstatic:

问题 Before I ask the question I like to provide the code for clarity. Below is my code for singleton class. public class CoreData { private boolean VarA; private static CoreData instance = null; protected CoreData() { // Exists only to defeat instantiation. } public static CoreData getInstance() { if(instance == null) { instance = new CoreData(); } return instance; } public boolean getVarA(){ return VarA; } public void setFirstTime(boolean B){ VarA = B; } } Now I have few questions to ask What

问题 I want to have dict / list to which I can add values, just like models can be added to the admin register in django ! My attempt : ( package -> __init__.py ) # Singleton object # __init__.py (Package: pack) class remember: a = [] def add(data): a.append[data] def get(): return a obj = remember() # models1.py import pack pack.obj.add("data") # models2.py import pack pack.obj.add("data2") print pack.obj.get() # We should get: ["data", "data2"] # We get : ["data2"] How to achieve the desired

问题 I have a picker (UIPickerView) that I think should be a singleton that will be displayed in more than one view. I am using a tabbed UI and 2 of the views use the same picker. How I can create one instance of the picker so that I can call reloadAllComponents on it when the data changes, and have both views show the same selection? EDIT: only one view is visible/active at a time. In addition to the picker, there will be other controls in that common header. I have created a view from an xib

问题 I'm confused about this code I got from here: import functools def singleton(cls): """Make a class a Singleton class (only one instance)""" @functools.wraps(cls) def wrapper_singleton(*args, **kwargs): if not wrapper_singleton.instance: wrapper_singleton.instance = cls(*args, **kwargs) return wrapper_singleton.instance print('****') wrapper_singleton.instance = None return wrapper_singleton @singleton class TheOne: pass Why doesn't wrapper_singleton.instance = None set the instance to none