Add interfaces to groovy enums? - maven

Question

I am unable to add interfaces to groovy enums.
example:
interface DeviceType.groovy
public interface DeviceType{
public String getDevice()
}
enum Device.groovy
public enum Devices implements DeviceType {
PHONE{
public String getDevice(){
return "PHONE"
}
}, ALARM {
public String getDevice(){
return "ALARM"
}
}
}
Simple Test
public class MainTest(){
public static void main(String [] args) {
System.out.println(Devices.PHONE.getDevice());
//should print phone
}
}
This is pseudo code, but a pretty good example.
When I use it with Groovy, I get an error from IntelliJ that I need to make the interface abstract.
If I make it abstract, maven won't compile saying it can't be both static and final.
Any tips?

Answer 1

You need to define getDevice() in the enum. Then you can override it, like this:
enum Device.groovy
public enum Devices implements DeviceType {
PHONE{
public String getDevice(){
return "PHONE"
}
}, ALARM {
public String getDevice(){
return "ALARM"
}
};
public String getDevice(){
throw new UnsupportedOperationException();
}
}

Answer 2

Since an enum is a class, and your class is implementing the interface, it needs to implement the function. Right now what you have is an enum that's NOT implementing the function, whose instances are each subclasses that do have a function of the same name. But since the enum itself doesn't have it, that's not good enough.
I'd like to offer my preferred syntax for a situation such as this:
public enum Devices implements DeviceType {
PHONE("PHONE"), ALARM("ALARM")
private final String devName
public String getDevice() { return devName }
private Devices(devName) { this.devName = devName }
}
Or, if the "device" is always going to match the name of the enum instance, you might as well just return that:
public enum Devices implements DeviceType {
PHONE, ALARM
public String getDevice() { return name() }
}