如何定义一个接口方法，其不同的实现可以返回<t> ， 列表<t> ， 列表<list<t> &gt; 其中 T 是自定义 class </list<t></t></t>

Question

interface IParser
{
     return type parseData(list<byte> data);
}

Where return type can be a T , List<T> or List<List<T>>

Answer 1

Declare your interface like this

interface IParser<T>
{
    T ParseData(List<byte> data);
}

Can be used like this:

public class Parser<T> : IParser<T>
{
    public virtual T ParseData(List<byte> data) //virtual is optional
    {
        //do stuff and return T
        //T could be anything, a List, a struct, a class what ever
        return default(T);
    }
}

If you need a specific parser you could do this:

public class StringParser : Parser<string>
{
    public override string ParseData(List<byte> data)
    {
        return string.Empty;
    }
}

Or if you need a specific parser for a collection of T

public class CollectionParser<TItem> : Parser<IEnumerable<TItem>>
{
    public override IEnumerable<TItem> ParseData(List<byte> data)
    {
        return Enumerable.Empty<TItem>;
    }
}

Answer 2

Something like this:

public interface IParser<TOut> where TOut : class
{
    TOut ParseData(List<byte> data);
}

edit

Since the question was about T as a custom class thereby verify that the type of TOut is class. Maybe a good addition would be as following:

public interface IParser<in TIn, out TOut> where TOut : class
{
    TOut ParseData(TIn data);
}

and the implementation would be:

class Parser : IParser<List<byte>, CustomClass>
{
    CustomClass ParseData(List<byte> data)
    {
     return new CustomClass();
    }
}