Too much singletons in the project - is it a bad practice?

Question

In almost every project I create a few classes which implement Singleton pattern. For example, data manager - if there\'s some work with file system, data loader - if an app

Answer 1

There's a lot of discussion on this topic. For some people, Singleton is considered an anti-pattern. It can be very useful however, but it tends to be much trickier to implement correctly than it seems. There are situations where its use is justified, for instance to have a unique entry point for data common to a whole application - and therein lies the tricky part, it's global state in disguise, safe for use if and only if the data is immutable.

As an aside note JEE6, the latest version of Java's Enterprise Edition, now includes support for the Singleton pattern as an EJB component. But think about it for a moment, it took six revisions of the standard to finally get it done!