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Asked: 2026-05-11T10:21:30+00:00

I’m fairly new to java, and am used to enums essentially beeing nothing more

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I’m fairly new to java, and am used to enums essentially beeing nothing more than a named list of integers.

Now I’m writing an implementation where a parent class has a couple of methods that take an enum value as argument. The enum will be defined in child classes, and will differ slightly. Since enums basically seem to behave like classes, this doesn’t work the way I expected it to. Each enum defined will be considered a different type of object and the parent class will have to pick one of the defined enums to take as argument.

Is there a good way to make the parent class accept any enum defined in it’s child-classes? Or will I have to write a custom class for this?

Edit: Here is my example, fixed as per Jon Skeets answer, for anyone who is looking into how to do this later on:

class Parent {    protected interface ParentEvent {}    private HashMap<ParentEvent, String> actions = new HashMap<ParentEvent, String>();     protected void doStuff(ParentEvent e){        if(actions.containsKey(e)){          System.out.println(actions.get(e));       }     } }  class Child extends Parent {    enum Event implements ParentEvent {EDITED, ADDED, REMOVED}     public void trigger(){       doStuff(Event.REMOVED);    } }
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1 Answer

  1. You could make your enums implement an interface, then give your parent class method a parameter of that interface type.

    As you say, enums are rather different in Java. They’re not named numbers – they’re a fixed set of values, but those values are object-oriented (i.e. they can use polymorphism etc). Java enums pretty much rock, except for a few tricksy issues around initialization ordering.

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