How many responsibilities does the Singleton pattern implement?

The Singleton pattern implements a single main responsibility — to ensure that a class has only one instance, and to provide a global point of access to that instance.

That is, Singleton is responsible for:

• Controlling object creation to prevent multiple instances.
• Providing a single object for use throughout the application.

Example in Java:

public class Singleton {
    private static Singleton instance;

    private Singleton() { }

    public static synchronized Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }
}

Thus, the pattern addresses the management of a single state or resource in the application.