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c#boxinggeneric-collectionsunboxing

Boxing and Unboxing with Generic Collections


In interview i had been asked for Boxing and Unboxing and i explained it. After that i asked for Generic Collections. I explained the below code and from here they asked how boxing operation applied here in the below code. I am not sure about this answer.

public abstract class DataAccess<T, TKey>
{
   --CRUD Operations here
}

public class AdminDataAccess : DataAccess<Admin, long>
{
    --code here
}

Solution

  • There is no boxing. Boxing does not apply to generic type parameters. It only applies when they are actually used in code and are actually boxed/unboxed by said code.

    EDIT: ..an example, although I think I explained it fairly well..

    This will box:

    public abstract class DataAccess<T, TKey> where TKey : struct {
        private object _boxedKey;
    
        private void DoSomething(TKey key) {
            _boxedKey = key;
        }
    }
    

    Without some code forcefully boxing/unboxing a value type, your generic type parameters don't have anything to do with boxing or unboxing.