After you got started with Java programming, chances are you will want to use some design patterns to organise your Java classes.
One common object oriented design pattern is the Singleton pattern. The Singleton pattern is a technique where you can apply to ensure that there is only one instance of your Java class per runtime.
The Singleton pattern is usually used for grouping functionalities that allow callers to act on a single set of state. Examples of cases where the Singleton pattern can be applied include:
- A class that keeps track of a customized configurations from a configuration file.
- A class that facilitates interactions with a database system.
- A class that performs logging.
- A class that caches data read from previous database calls.
This post documents some ways to implement the Singleton pattern in Java.