Single instance analysis of Java design pattern

This article describes the singleton pattern of Java design pattern. Share with you for your reference, as follows:

Singleton pattern is a relatively simple pattern, which is defined as follows:

Ensure a class has only one instance,and provide a global point of access to it. (ensure that there is only one instance of a class, and instantiate it by itself and provide this instance to the whole system)

Singleton mode, a very simple mode. In fact, in Android development, singleton mode is used in many places, such as some tool classes, JSON data analysis classes, local database operation classes, etc. Common code of singleton mode:

I hope this article will be helpful to you in Java programming.