singleton : Java Glossary
Singletons are the design pattern when you want only one instance of a class created.
You make the constructor private, and give access to the instantiated object via a
static instance method that creates the object if it has not been created
already. The advantages of this technique over using class variables and methods are:
Here is typical code courtesy of Chris Smith for postponing the creation of the
singleton in a way that is thread safe.
- You can change your mind later and allow multiple instances without rewriting
all your code.
- You can override methods. With static methods, no overriding is possible.
- If you never use the singleton object, it never gets created, saving
RAM (Random Access Memory).
- The client can choose his own short name for the singleton to represent the
- The official reason is it makes it easier to extend to multiple instances or a