C# 泛型列表 <T>如何获得T的类型?

问题描述

我正在做一个反射项目，现在我卡住了.

I'm working on a reflection project, and now I'm stuck.

如果我有一个 myclass 的对象可以保存一个 List，如果属性 myclass.SomList 是空的?

If I have an object of myclass that can hold a List<SomeClass>, does anyone know how to get the type as in the code below if the property myclass.SomList is empty?

List<myclass> myList = dataGenerator.getMyClasses();
lbxObjects.ItemsSource = myList;
lbxObjects.SelectionChanged += lbxObjects_SelectionChanged;

private void lbxObjects_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    Reflect();
}

Private void Reflect()
{
    foreach (PropertyInfo pi in lbxObjects.SelectedItem.GetType().GetProperties())
    {
        switch (pi.PropertyType.Name.ToLower())
        {
            case "list`1":
            {
                // This works if the List<T> contains one or more elements.
                Type tTemp = GetGenericType(pi.GetValue(lbxObjects.SelectedItem, null));

                // but how is it possible to get the Type if the value is null?
                // I need to be able to create a new object of the type the generic list expect.
                // Type type = pi.getType?? // how to get the Type of the class inside List<T>?
                break;
            }
        }
    }
}

private Type GetGenericType(object obj)
{
    if (obj != null)
    {
        Type t = obj.GetType();
        if (t.IsGenericType)
        {
            Type[] at = t.GetGenericArguments();
            t = at.First<Type>();
        }
        return t;
    }
    else
    {
        return null;
    }
}

推荐答案

Type type = pi.PropertyType;
if(type.IsGenericType && type.GetGenericTypeDefinition()
        == typeof(List<>))
{
    Type itemType = type.GetGenericArguments()[0]; // use this...
}

更一般地，要支持任何IList，您需要检查接口:

foreach (Type interfaceType in type.GetInterfaces())
{
    if (interfaceType.IsGenericType &&
        interfaceType.GetGenericTypeDefinition()
        == typeof(IList<>))
    {
        Type itemType = type.GetGenericArguments()[0];
        // do something...
        break;
    }
}

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