What is the purpose for using an empty interface that extends another in Java?

问题

I just begin to maintain a Java MVC project which use Java Guice Framework.

In almost the entire code, first developers passed as parameter an empty model interface extending another interface.

Here's the first Interface:

public interface FooModel extends ModelInterface {

}

And the other interface:

 public interface ModelInterface {
        public void addListener(FooListener fooListener);
        void setFoo(boolean blop);
        boolean isFoo();
    }

That does not make any sense for me.

Is there a good reason/pattern use empty interface, in Java? Maybe for Guice?

回答1:

Here is a good motivation for "marker interfaces". They are especially useful in aspect-oriented programming where they give you a point to attach to (and I guess Guice is just such a framework).

回答2:

Only reason i know to use an empty interface would be as a marker interface. There are some examples like java.lang.Cloneable or Serializable.

回答3:

It could be used to mark a class for a specific use.

Example: IRequiresSessionState

来源：https://stackoverflow.com/questions/10590526/what-is-the-purpose-for-using-an-empty-interface-that-extends-another-in-java