IEqualityComparer Not calling subclass in dictionary

Question

I'm trying to implement an IEqualityComparer on a sub class which will be stored as a key to a dictionary.

the following is what i have

public class SuperClass : IEqualityComparer<SuperClass> {

    public virtual bool Equals(SuperClass dictKeyComparerA, SuperClass dictKeyComparerB) {
        throw new NotImplementedException();
    }

    public virtual int GetHashCode(SuperClass dictKeyComparer) {
        throw new NotImplementedException();    
    }
}

public class SubClass : SuperClass {

    private readonly string application;

    public SubClass(string application) {
        this.application = application; 
    }

    public override bool Equals(SuperClass dictKeyComparerA, SuperClass dictKeyComparerB) {
        throw new NotImplementedException();
    }

    public override int GetHashCode(SuperClass dictKeyComparer) {
        throw new NotImplementedException();    
    }   
}

and i have the following to try to search the dictionary:

Dictionary<SubClass, List<string>> TestDict3 = new Dictionary<SubClass, List<string>>(new SubClass("random"));

    var testKeyb = new SubClass("12345");
    var testListb = new List<string>{"aaaaa"};

    TestDict3.Add(testKeyb, testListb);

    var testKey2b = new SubClass("12345");
    var testKey3b = new SubClass("56973");

    if(TestDict3.ContainsKey(testKey2b)) {
        Console.WriteLine("found testKey2b");
    }
    else {
        Console.WriteLine("did not found testKey2b");   
    }

    if(TestDict3.ContainsKey(testKey3b)) {
        Console.WriteLine("found testKey3b");
    }
    else {
        Console.WriteLine("did not found testKey3b");   
    }

When the code is ran, it returns a not implemented exception because it is calling the super class GetHashCode function instead of the override function.

Any thoughts on the issue?

in your example both the super class and the sub class both throw a not implmented exception — Scott Chamberlain, Mar 31 '16 at 19:54

Tim Rutter · Answer 1 · 2016-03-31T20:04:31.710

Hmmmmm, - all your functions call:

throw new NotImplementedException();

Which is why they throw a NotImplementedException...

I just tried some sensible code in the SubClass implementations and it works.

 public override bool Equals(SuperClass dictKeyComparerA, SuperClass dictKeyComparerB)
{
    var a = dictKeyComparerA as SubClass;
    var b = dictKeyComparerB as SubClass;
    return a.application == b.application;
}

public override int GetHashCode(SuperClass dictKeyComparer)
{
    return application.GetHashCode();
}

IEqualityComparer Not calling subclass in dictionary

1 Answers1