Enforcing Java Singletons is Very Hard
Background A singleton is a class that is instantiated exactly one time and can be used to represent "global" or system wide components. Common usages of singletons include loggers, factories, window managers or platform components. My general tip is to avoid using singletons when possible, because it is difficult to break out or override functionality and also to write test mocks and they also tend to create a bad over all code structure. As it turns out in this post, they are also insecure. know more java training Many efforts has been made to devise good singleton patterns but there is one surprisingly easy and efficient way of doing it. However, there is really no rock solid way of guaranteeing that the singleton integrity is not breached. Read this post and see if you agree. The Final Field Scheme This solution relies on keeping the constructor private and exporting a public static final member to provide singleton access like this: public class FooSingleton {