Confusion in marker interface

问题

Marker interface means interface which have no methods. Then why we call the Runnable interface as a marker interface, even though it has run() method. And one more thing how many marker interfaces are there in java ?

回答1:

Then why we call the Runnable interface as a marker interface

We don't. You just made that up.

回答2:

Runnable is not a Marker interface. AFAIK, Serializable, Clonable, SingleThreadModel, EventListener, RandomAccess, Remote are Marker Interfaces.

来源：https://stackoverflow.com/questions/2294350/confusion-in-marker-interface