Questions tagged [singleton]

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68
votes
5answers
12k views

When is Singleton appropriate? [closed]

Some hold that the Singleton Pattern is always an anti-pattern. What do you think?
576
votes
13answers
239k views

So Singletons are bad, then what?

There has been a lot of discussion lately about the problems with using (and overusing) Singletons. I've been one of those people earlier in my career too. I can see what the problem is now, and yet, ...
29
votes
5answers
27k views

What is the difference between all-static-methods and applying a singleton pattern? [duplicate]

I am making a database to store information about the users of my website (I am using stuts2 and hence Java EE technology). For the database I'll be making a DBManager. Should I apply singleton ...
34
votes
3answers
57k views

When to use a Singleton and when to use a static class [duplicate]

I've searched about this here and on StackOverflow and found some differences between the two. But I'm still not sure in what cases one would prefer a Singleton, and in what cases one would choose to ...
28
votes
9answers
19k views

Alternatives to the singleton pattern

I have read different opinions about the singleton pattern. Some maintain that it should be avoided at all costs and others that it can be be useful in certain situations. One situation in which I ...
14
votes
3answers
8k views

What are the downsides of implementing a singleton with Java's enum?

Traditionally, a singleton is usually implemented as public class Foo1 { private static final Foo1 INSTANCE = new Foo1(); public static Foo1 getInstance(){ return INSTANCE; } private ...
7
votes
3answers
4k views

How to create a manager class without global variables nor singletons?

I would like to implement some kind of manager class in my application. It will be in charge of loading textures, processing them, distributing them etc... At first, I wanted to make a global ...
5
votes
3answers
1k views

Why don't we use a class and its static members to do what a singleton does?

In Java,C++,Objective C, C#, and all other similar OOP languages, Why don't we use a class with static methods and vars instead of going through a singleton syntax having to deal with various ...
26
votes
7answers
3k views

The Singleton Pattern [duplicate]

Possible Duplicate: When is Singleton appropriate? I am a new programmer (4 months into my first job) and have recently taken an interest in design patterns. One that I have used recently is the ...
17
votes
4answers
17k views

Dependency Injection and Singleton. Are they two entirely different concepts?

I've been hearing about using the dependency injection over Singleton for my colleague. I still can't make out if it they are two orthogonal patterns which can be replaced with one another? Or is DI a ...
8
votes
3answers
11k views

React Native - Is using a singleton the best alternative to DI?

I've been reading a lot about the singleton pattern and how it's "bad" because it makes the classes using it hard to test so it should be avoided. I've read some articles explaining how the singleton ...
3
votes
2answers
4k views

Converting static utility class into singleton

In company where I work we have lots of "utility" classes, each has lots of code inside (thousands of lines), and they are all static. And one static methods call anothers. The problem here is that ...
1
vote
4answers
489 views

Is this a candidate for Singleton?

I have an external thermometer connected via USB that is controlled by my SW. Different parts of my system will use it but never at the same time (all in one thread). However, it is a single device ...
42
votes
11answers
5k views

Are so called “cross-cutting concerns” a valid excuse to break SOLID/DI/IoC?

My colleagues like to say "logging/caching/etc. is a cross-cutting concern" and then proceed using the corresponding singleton everywhere. Yet they love IoC and DI. Is it really a valid excuse to ...
16
votes
3answers
3k views

Could a singleton type replace static methods and classes? [duplicate]

Possible Duplicate: What is the difference between all-static-methods and applying a singleton pattern? In C# Static methods has long served a purpose allowing us to call them without ...
3
votes
4answers
3k views

Is the singleton pattern prone to thread safety problems?

Is the singleton pattern prone to thread safety problems? If so, what are the best methods to work around them?
5
votes
1answer
11k views

Singleton with dependency injection ,is that a good practice in some cases?

It's a good idea to have a Singleton implementation with dependency injection? I have some classes that performs some heavy tasks on instantiation (related to database loading). I would like to use ...
1
vote
1answer
399 views

Do you use static keyword to declare single instance pattern? [duplicate]

I just come across this code and find it interesting to know whether you consider this as another single instance pattern? public class Initiator { private static String str; // there is many ...