Singleton is frequently used in applications where resource may be expensive to create and no instance specific state needs to be maintained. For example, when creating database connection, a singleton may be needed. Today we will share the famous Singleton design pattern in Java.1. DefinitionSingleton design pattern is a design pattern that restricts the instantiation of a class to one object. It is one of the most well-known design patterns.2. ApplicationSingleton can be used in many occasions, for example, one database can have only one connection or connection coun...