I have a basic question in Java, but it’s a general question in OOP. Why do interfaces allow fields to be set? Doesn’t that run contrary to what an interface is supposed to do?
The way I made sense of it, an interface is what in English would be an adjective. So, if my class implements the interfaces Runnable and Serializable, I’m ensuring the user that my class will satisfy the conditions to be Runnable and Seriablizable. However, that would mean interfaces are “stateless”, but they are allowed to have fields in Java…
Am I missing something?
All fields in interface are
public static final, i.e. they are constants.It is generally recommended to avoid such interfaces, but sometimes you can find an interface that has no methods and is used only to contain list of constant values.