Is there any difference between singleton and static class?

[Thennam Pandian]

Assume that we have a class with full of static methods. To access this methods we don't need to create a object.

Is there any difference between singleton object and this class?
which is better and how?

[Hussein Baghdadi]

Singleton isn't about not creating an instance, Singleton makes sure that there is only one instance of a class (like a FileSystemManager object for example).
A class with only static methods is usually called a "Utility class".

[Avishkar Nikale]

John Todd wrote:Singleton isn't about not creating an instance, Singleton makes sure that there is only one instance of a class (like a FileSystemManager object for example).
A class with only static methods is usually called a "Utility class".

John,

Nice explanation. Concise & to the point.

Thennam,

Singleton is one of simplest OO pattern to explain but one of the rather difficult one to implement (depending on your system, class loaders etc).

As far as comparison goes as John said, it is apples vs oranges, they have completely different tasks in a system.

[Jimmy Clark]

While there are usually many more efficient ways to design OO applications without using the Simpleton design pattern, the pattern does have considerable benefits when compared to class operations, e.g. more flexibility.

[Remko Strating]

Simply because if you use an interface for your class you need an instance which implements that interface. This is for me the main reason for using the singleton pattern. I have some utility classes but I don't want the rest of my code to know the implementation details but I don't want the create lot of objects. So I use the singleton pattern for generating 1 object which implements the interface.