如何将字典值作为通用列表

Question

I just want get a list from Dictionary values but it's not so simple as it appears !

here the code :

Dictionary<string, List<MyType>> myDico = GetDictionary();
List<MyType> items = ???

I try :

List<MyType> items = new List<MyType>(myDico.values)

But it does not work :-(

Answer 1

怎么样：

var values = myDico.Values.ToList();

Answer 2

Off course, myDico.Values is List<List<MyType>> .

Use Linq if you want to flattern your lists

var items = myDico.SelectMany (d => d.Value).ToList();

Answer 3

Another variant:

    List<MyType> items = new List<MyType>();
    items.AddRange(myDico.values);

Answer 4

您可能希望将Values所有列表展平为单个列表：

List<MyType> allItems = myDico.Values.SelectMany(c => c).ToList();

Answer 5

我的OneLiner：

var MyList = new List<MyType>(MyDico.Values);

Answer 6

进一步研究Slaks的答案，如果你的字典中的一个或多个列表为null，则在调用ToList()时会抛出System.NullReferenceException ，安全地播放：

List<MyType> allItems = myDico.Values.Where(x => x != null).SelectMany(x => x).ToList();

Answer 7

        List<String> objListColor = new List<String>() { "Red", "Blue", "Green", "Yellow" };
        List<String> objListDirection = new List<String>() { "East", "West", "North", "South" };

        Dictionary<String, List<String>> objDicRes = new Dictionary<String, List<String>>();
        objDicRes.Add("Color", objListColor);
        objDicRes.Add("Direction", objListDirection);

Answer 8

Another variation you could also use

MyType[] Temp = new MyType[myDico.Count];
myDico.Values.CopyTo(Temp, 0);
List<MyType> items = Temp.ToList();

Answer 9

Dictionary<string, MyType> myDico = GetDictionary();

var items = myDico.Select(d=> d.Value).ToList();

Answer 10

Use this:

List<MyType> items = new List<MyType>()
foreach(var value in myDico.Values)
    items.AddRange(value);

The problem is that every key in your dictionary has a list of instances as value. Your code would work, if each key would have exactly one instance as value, as in the following example:

Dictionary<string, MyType> myDico = GetDictionary();
List<MyType> items = new List<MyType>(myDico.Values);