c# - C#泛型列表<T>如何获取T的类型？

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How to get the type of T from a member of a generic class or method?

(16个答案)


7年前关闭。




我正在做一个反射(reflection)项目，现在被困了。

如果我有一个可以保存myclass的List<SomeClass>对象，如果myclass.SomList属性为空，有人知道如何获取以下代码中的类型吗？

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;
    }
}

最佳答案

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

通常，要支持任何IList<T>，您需要检查接口(interface):

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