Singleton with Arguments in Java

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I’ll make my point very clear: a singleton with parameters is not a singleton.

A singleton, by definition, is an object you want to be instantiated no more than once. If you are trying to feed parameters to the constructor, what is the point of the singleton?

You have two options. If you want your singleton to be initialized with some data, you may load it with data after instantiation, like so:

SingletonObj singleton = SingletonObj.getInstance();
singleton.init(paramA, paramB); // init the object with data

If the operation your singleton is performing is recurring, and with different parameters every time, you might as well pass the parameters to the main method being executed:

SingletonObj singleton = SingletonObj.getInstance();
singleton.doSomething(paramA, paramB); // pass parameters on execution

In any case, instantiation will always be parameter-less. Otherwise your singleton is not a singleton.

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