A Global Singleton is a class of which only one instance exists within a program.

Any attempt to use non-static members of the class involves performing operations on this one instance.




@Singleton
class SingletonClass {
 
    def invokeMe() {
        println 'invoking method of a singleton class'
    }
 
    static void main(def args) {
        SingletonClass.instance.invokeMe()
    }
}