非常感谢Jon和mquander-你们给了我足够的信息，可以帮助我以适当的通用方式解决此问题。这是我的解决方案，一种将对象转换为层次结构形式的通用扩展方法：
public static IEnumerable<Node<T>> Hierarchize<T, TKey, TOrderKey>( this IEnumerable<T> elements, TKey topMostKey, Func<T, TKey> keySelector, Func<T, TKey> parentKeySelector, Func<T, TOrderKey> orderingKeySelector){ var families = elements.ToLookup(parentKeySelector); var childrenFetcher = default(Func<TKey, IEnumerable<Node<T>>>); childrenFetcher = parentId => families[parentId] .OrderBy(orderingKeySelector) .Select(x => new Node<T>(x, childrenFetcher(keySelector(x)))); return childrenFetcher(topMostKey);}利用此小节点类：
public class Node<T>{ public T Value { get; private set; } public IList<Node<T>> Children { get; private set; } public Node(T value, IEnumerable<Node<T>> children) { this.Value = value; this.Children = new List<Node<T>>(children); }}它足够通用，可以解决各种问题，包括我的文本文件问题。好漂亮！
*更新*：这是您的使用方式：
// Given some example data:var items = new[] { new Foo() { Id = 1, ParentId = -1, // Indicates no parent Position = 0 }, new Foo() { Id = 2, ParentId = 1, Position = 0 }, new Foo() { Id = 3, ParentId = 1, Position = 1 }};// Turn it into a hierarchy! // We'll get back a list of Node<T> containing the root nodes.// Each node will have a list of child nodes.var hierarchy = items.Hierarchize( -1, // The "root level" key. We're using -1 to indicate root level. f => f.Id, // The ID property on your object f => f.ParentId, // The property on your object that points to its parent f => f.Position, // The property on your object that specifies the order within its parent );
