When should a class be a singleton?

Use the Singleton pattern when a class in your program should have just a single instance available to all clients; for example, a single database object shared by different parts of the program. The Singleton pattern disables all other means of creating objects of a class except for the special creation method.

When would you want to use Singleton pattern?

A singleton should be used when managing access to a resource which is shared by the entire application, and it would be destructive to potentially have multiple instances of the same class. Making sure that access to shared resources thread safe is one very good example of where this kind of pattern can be vital.

When would you use a class with static members and when would you use a singleton class?

While a static class allows only static methods and and you cannot pass static class as parameter. A Singleton can implement interfaces, inherit from other classes and allow inheritance. While a static class cannot inherit their instance members. So Singleton is more flexible than static classes and can maintain state.

When should you not use a singleton?

The only situation in which you should consider a singleton is when having more than one instance of already global data would actually be a logical or hardware access error….Related Links:

1. Brittleness invoked by Global State and Singletons.
2. Dependency Injection to Avoid Singletons.
3. Factories and Singletons.

Why do we need singleton class?

The purpose of the singleton class is to control object creation, limiting the number of objects to only one. The singleton allows only one entry point to create the new instance of the class. Singletons are often useful where we have to control the resources, such as database connections or sockets.

When would you use a static class?

Use a static class as a unit of organization for methods not associated with particular objects. Also, a static class can make your implementation simpler and faster because you do not have to create an object in order to call its methods.

What is the advantage of Singleton design pattern?

Instance control: Singleton prevents other objects from instantiating their own copies of the Singleton object, ensuring that all objects access the single instance. Flexibility: Since the class controls the instantiation process, the class has the flexibility to change the instantiation process.

What is difference between singleton class and static class?

A static class can’t be instantiated by anything other than itself. Main differences are: Singleton has an instance/object while static class is a bunch of static methods. Singleton can be extended e.g. through an interface while static class can’t be.

Why can’t we use a static class instead of singleton?

Intention of a singleton pattern is to ensure that a single instance of a class is instantiated. – Singleton object stores in Heap but, static object stores in stack. – We can clone the object of Singleton but, we can not clone the static class object.

Should you use singleton?

The truth is that singletons aren’t inherently bad if they’re used correctly. The goal of the singleton pattern is to ensure only one instance of a class is alive at any one time. Singletons are very much like the good things in life, they’re not bad if used in moderation.

What can I use instead of singleton?

The best way is to use a Factory pattern instead. When you construct a new instance of your class (in the factory) you can insert the ‘global’ data into the newly constructed object, either as a reference to a single instance (which you store in the factory class) or by copying the relevant data into the new object.

Can we use static class instead of Singleton?

– Singleton object stores in Heap but, static object stores in stack. – We can clone the object of Singleton but, we can not clone the static class object. – Singleton can use the Object Oriented feature of polymorphism but static class cannot. Answer: Singleton is just a design pattern and it can be subclassed.

What is a singleton class in Java?

A singleton should be used when managing access to a resource which is shared by the entire application, and it would be destructive to potentially have multiple instances of the same class. Making sure that access to shared resources thread safe is one very good example of where this kind of pattern can be vital.

Is there an acceptable reason to use a singleton?

On my quest for the truth I discovered that there are actually very few “acceptable” reasons to use a Singleton. One reason that tends to come up over and over again on the internets is that of a “logging” class (which you mentioned).

How many instances can a singleton instance have?

Feb 10 ’14 at 19:25 1 Singleton can be used as a manager object between the instances of other objects, thus there should be only one instance of the singleton where each other instances should communicate via the singleton instance. – Levent Divilioglu

What is an acceptable Singleton in Misko?

Logging is a specific example of an “acceptable” Singleton because it doesn’t affect the execution of your code. Disable logging, code execution remains the same. Enable it, same same. Misko puts it in the following way in Root Cause of Singletons, “The information here flows one way: From your application into the logger.