Thread Safety for Singleton mode

Singleton mode is a relatively simple one in design mode. For cases where there is only one instance of a class, such as window manager, print buffer pool, and file system, they are all examples of prototypes. Typically, the types of objects that are accessed by different objects throughout a software system require a global access pointer, which is the application of the well-known singleton pattern.

Classic single-case mode with three types, lazy, a hungry man and lazy single-case pattern improvement

"Lazy-style" is to build this singleton object when you really use it, so it is thread insecure

Lazy type If you create an instance object without adding synchronized, the access to the object is not thread-safe.

Test the lazy type of function

Test results

A hungry man is thread-safe , creating a static object at the same time as the class is created for the system to use, and not change later.

Lazy-style improvement

Using static inner classes, the object is generated when the class is called

Thread Safety for Singleton mode