Condition.Equals': Interfaces cannot declare types

Question

I am getting this error:

"Condition.Equals': Interfaces cannot declare types".

How do I do this correctly?

 public interface Condition<Expected> {

        public bool verify(Expected expected, object actual);

        public class Equals : Condition<object> {   

            public bool verify(object expected, object actual) {
                return expected==actual || (expected!=null && expected.Equals(actual));
            }
        }

Interfaces can't contain class definitions. maybe you want ot create abstract class instead? — Kamil T, May 19 '16 at 11:16

score 0 · Answer 1 · answered May 19 '16 at 11:18

Move class declaration outside the interface; all you can do within the interface is declaring methods and properties:

public interface Condition<Expected> {
  // you can't declare interface method as public or, say, private: 
  // it's the implementing class that provides the access modifier
  bool verify(Expected expected, object actual);
}

public class Equals : Condition<object> {   
  public bool verify(object expected, object actual) {
    return expected == actual || (expected != null && expected.Equals(actual));
  }
}

I'm fairly new to C#, just translated this from my Java code so I'm still getting the hang of it. Thanks! — King Kong, May 19 '16 at 11:46

Condition.Equals': Interfaces cannot declare types

1 Answers1