Here's an outline of the structure of my inheritance-based solution.

    abstract class Decoder
    {
        public abstract String decode(String code);
    }
    
    class AsciiDecoder extends Decoder
    {
        ...
    }
    
    class EnumeratedDecoder extends Decoder
    {
        public EnumeratedDecoder(String coding)
        {
           ...
        }
    
        public String decode(String code)
        {
            ...
        }
    }
    
    class EBCDICEnumeratedDecoder extends EnumeratedDecoder
    {
        public EBCDICEnumeratedDecoder(String coding)
        {
            ...uses super...
        }
    
        public String decode(String code)
        {
            ...uses super...
        }
    }