The Singleton Pattern
The singleton pattern is one of the simplest design patterns in Java. This design pattern is considered a creational pattern, as this pattern provides one of the best ways to create an object.
Sometimes it’s important for some classes to have exactly one instance. There are many times when we only need one instance of an object and if we instantiate more than one we’ll run into all sorts of problems, like incorrect program behavior, overuse of resources, or inconsistent results. You may require only one object of a class, for example, when you are creating: