How to call a singleton method?

Question

I have a singleton object like:

Object o = new Object () {
  public void test() {
    //...
  }
};

But I cannot use o.test() because the class/interface does not have that method. Is there any way to achieve this using meta programming such as getMethods? Please do not suggest declaring an interface.

It may make more sense to have it be a Runnable instead, since you're just running a void method, right? — phflack
– phflack, Commented Nov 20, 2015 at 18:07
@phflack It is more just a sample code here... It is more complex in my real code. — SwiftMango
– SwiftMango, Commented Nov 20, 2015 at 18:14
In that case, you should probably go with reflection if you dislike the elegancy of interfaces in OOP — phflack
– phflack, Commented Nov 20, 2015 at 18:17
@phflack It is just a little annoying because there is only one such object and I have to create a new interface just for it — SwiftMango
– SwiftMango, Commented Nov 20, 2015 at 18:19
Even with only being used once, just how many methods are in it? If there are a lot, it might make more sense to use a local class which you only ever use once, but is a bit more readable and maintainable. — phflack
– phflack, Commented Nov 20, 2015 at 18:23

M A · Accepted Answer · 2015-11-20 18:03:23Z

5

By reflection:

o.getClass().getMethod("test", null).invoke(o, null);

But this is normally a very ugly thing to do.

answered Nov 20, 2015 at 18:03

M A

73.2k14 gold badges150 silver badges182 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

SwiftMango Over a year ago

I did this o.getClass().getMethod("test").invoke(o);... works and a bit simpler

Michael Queue · Accepted Answer · 2015-11-20 18:06:36Z

1

Alternatively...

Class cls = Class.forName(className);
Method method = cls.getMethod("test", new Class[0]);
Object o = method.invoke(null, new Object[0]);

answered Nov 20, 2015 at 18:06

Michael Queue

1,4103 gold badges26 silver badges39 bronze badges

1 Comment

David Conrad Over a year ago

It's an anonymous inner class, so Class.forName won't work.

Collectives™ on Stack Overflow

How to call a singleton method?

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related