Java Singleton: Key Use Cases

There are several scenarios in which the Java Singleton pattern can be used:

1. Database connection pool: In an application, database connections are a relatively scarce resource, so it is necessary to use singleton pattern to manage database connections, ensuring that only one connection pool instance is created and used.
2. Logger: Use the singleton pattern to create a global logger in the application, making it easy to log messages throughout the entire application.
3. Configuration file reader: In an application, there is usually a configuration file to store some configuration information. Using the singleton pattern ensures that only one instance of the configuration file reader is created, and the configuration information can be shared throughout the entire application.
4. Thread pool: In a multi-threaded environment, a global thread pool is created using the singleton pattern to conveniently share thread resources throughout the entire application.
5. Cache Manager: Use the singleton pattern to create a global cache manager within an application, enabling the sharing of cached data throughout the entire application.
6. GUI components: In graphical user interface (GUI) applications, use the singleton pattern to create some global GUI components to ensure only one instance is created and can be shared throughout the entire application.

In general, singleton pattern is suitable for scenarios that require only one instance, ensuring global uniqueness, facilitating shared resources and data, etc.