Require a method of an instantiated class to be called

Question

Let's say I have this code:

public class MyClass {
    public void doSomething(int value) {

    }
}
public class MyNewClass {
    public static void main(String args[]) {
        MyClass myClass = new MyClass();
    }
}

Would it be possible to get a compiler error that doSomething(int) from MyClass has not been called in MyNewClass? I know realistically you would put that method in the constructor but this question is out of curiosity.

Would you mind explaining your use case for this? Look at factory methods and private constructors if additional set up is needed after instantiation. — Paul Bellora, Aug 13 '13 at 16:04
Using plain Java, no. You can get something like this using aspect programming e.g. [aspectj](http://eclipse.org/aspectj/) — Luiggi Mendoza, Aug 13 '13 at 16:04
You'd probably have to [use custom annotations](http://stackoverflow.com/questions/10205261/how-to-create-custom-annotation-with-code-behind) to enforce something like this — Brad Mace, Aug 13 '13 at 16:07
@Paul Bellora Well I was thinking along the lines of some information you would need for a part of a class to work but that you would not necessarely have when you instantiate it. But yeah, after thinking about it for a while, I can't come up with a specific scenario where you would absolutely need this. That's why I put out of curiosity. — user2657455, Aug 13 '13 at 17:31
The answers given are quite interesting and diverse. Thanks! — user2657455, Aug 13 '13 at 17:32
Ok, I found a situation where this would be very useful. In android, onActivityResult is only available to an activity. If I make a separate class that does not extend/implement onActivityResult, I would have to call (using the example above) doSomething(int value), otherwise the class will not do it's job. — user2657455, Aug 14 '13 at 15:48

score 0 · Accepted Answer · answered Aug 13 '13 at 16:05

The closest you can come to this is using code coverage tools. Providing you have a full set of unit tests, they will allow you to identify, for example, which methods are never called. I can't recommend one library in particular but there are plenty available.

Require a method of an instantiated class to be called

1 Answers1