我经常将列表公开为ReadOnlyCollection<T>
s,即
public class Class
{
List<string> list;
public ReadOnlyCollection<string> TheList
{
get { return list.AsReadOnly(); }
}
}
对IDictionary<T,U>
SortedList<string, string>
等{{1}}执行此操作的最佳方式是什么?
答案 0 :(得分:4)
public class ReadOnlyDictionary<TKey, TValue> : IDictionary<TKey, TValue>
{
private readonly IDictionary<TKey, TValue> sourceDictionary;
public ICollection<TKey> Keys
{
get { return sourceDictionary.Keys; }
}
public ICollection<TValue> Values
{
get { return sourceDictionary.Values; }
}
public TValue this[TKey key]
{
get { return sourceDictionary[key]; }
set { throw new NotSupportedException(); }
}
public int Count
{
get { return sourceDictionary.Count; }
}
public bool IsReadOnly
{
get { return true; }
}
public ReadOnlyDictionary(IDictionary<TKey, TValue> sourceDictionary)
{
AssertUtilities.ArgumentNotNull(sourceDictionary, "sourceDictionary");
this.sourceDictionary = sourceDictionary;
}
void IDictionary<TKey, TValue>.Add(TKey key, TValue value)
{
throw new NotSupportedException();
}
public bool ContainsKey(TKey key)
{
return sourceDictionary.ContainsKey(key);
}
bool IDictionary<TKey, TValue>.Remove(TKey key)
{
throw new NotSupportedException();
}
public bool TryGetValue(TKey key, out TValue value)
{
return sourceDictionary.TryGetValue(key, out value);
}
void ICollection<KeyValuePair<TKey, TValue>>.Add(KeyValuePair<TKey, TValue> item)
{
throw new NotSupportedException();
}
void ICollection<KeyValuePair<TKey, TValue>>.Clear()
{
throw new NotSupportedException();
}
public bool Contains(KeyValuePair<TKey, TValue> item)
{
return sourceDictionary.Contains(item);
}
public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex)
{
sourceDictionary.CopyTo(array, arrayIndex);
}
bool ICollection<KeyValuePair<TKey, TValue>>.Remove(KeyValuePair<TKey, TValue> item)
{
throw new NotSupportedException();
}
public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
{
return sourceDictionary.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return ((IEnumerable)sourceDictionary).GetEnumerator();
}
}
[编辑] @Simon Buchan和@Cory Nelson指出,对于那些不受支持的方法,最好使用隐式接口实现。相应地更新了代码。
答案 1 :(得分:1)
创建一个ReadOnlyDictionary类,它将IDictionary实现为内部Dictionary实例的包装器。对于修改字典的方法,抛出异常。实现IsReadOnly以返回true。实现所有其他方法以传递给内部Dictionary实例。
答案 2 :(得分:0)
您可以使用标准的 LINQ 方法来实现。
创建源列表:
List<String> myList = new List<String>() { "A", "B", "C" };
使用 .ToDictionary
linq 扩展方法将您的列表投影到字典中:
var myDictionary = myList.ToDictionary(listItem => listItem);
注意:lambda 表达式从你的列表中偷看一个键(记住该字典只能包含唯一键;否则考虑使用 ILookup
表示列表字典)。
将你的字典改造成一个 SortedDictionary 实例:
var mySortedDictionary = new SortedDictionary<string, string>(myDictionary);
将您的排序字典公开为 IReadOnlyDictionary
接口,如下所示:
public IReadOnlyDictionary MemberDictionary { get; private set; );
// ...somewhere in your constructor or class's initialization method...
this.MemberDictionary = mySortedDictionary;