"The type 'System.Windows.Forms.TreeNodeCollection' has no constructors defined"

I have this code:

    private TreeNodeCollection treeCollection;

    public Cl开发者_如何转开发ient(TcpClient c)
    {
        this.tcpClient = c;
        this.tree = null;
        this.treeCollection = new TreeNodeCollection();
        this.treeCollection.Clear();
    }

    public void AddNode(string node)
    {
        this.treeCollection.Add(node);
    }

the this.treeCollection = new TreeNodeCollection(); returns

The type 'System.Windows.Forms.TreeNodeCollection' has no constructors defined

And if im deleting the this row i get that treeCollection is never assigned and will always be null...

Field 'Client.treeCollection' is never assigned to, and will always have its default value null

How can i assign the treeCollection as a new TreeNodeCollection so i can add nodes to it using my AddNode method?

---

TreeNodeCollection has an internal factory or constructor, so it can only be used by the TreeView control.

But... you don't need it. Just use a single node as your root node. Then clear its children with

rootNode.Nodes.Clear();

Or if you must, just create a

List<TreeNode>

---

It seems that the TreeNodeCollection isn't supposed to be created by a user. Instead, it is exposed by the readonly property "Nodes" of the TreeView Class.

Seeing that it's available since .Net 1.0, I consider it a relic from a time where generics didn't exist and programmers had to enforce strong typing by exposing such custom classes.

Today, a better design would probably expose an IList<TreeNode> or even an IDictionary<String, TreeNode>. Conversely, if you want to store TreeNodes yourself, you may use a List<TreeNode> or a Dictionary<String, TreeNode>, depending on how you want to access your nodes...

Personaly, I'd prefer to create a custom version of System.Collections.ObjectModel.KeyedCollection<String, TreeNode> (it would still keep the nodes in the insertion order but would also allow for keyed access). Your milleage may vary.

---

You can obtain a new TreeNodeCollection this way:

public TreeNodeCollection NewTreeNodeCollection(){
    TreeView tmp = new TreeView();
    return tmp.Nodes;
}

---

public class UGTreeNodeCollection {

    public UGTreeNodeCollection(TreeNodeCollection TreeNodeCollectionItem)
    {
        NodeCollection = TreeNodeCollectionItem;
    }

    private TreeNodeCollection NodeCollection;
    public TreeNode Add(string text)
    {
        return NodeCollection.Add(text);
    }

    public int Add(TreeNode node)
    {
        return NodeCollection.Add(node);
    }

    public TreeNode Add(string key, string text)
    {
        return NodeCollection.Add(key, text) as TreeNode;
    }

    public TreeNode Add(string key, string text, int imageIndex)
    {
        return NodeCollection.Add(key, text, imageIndex);
    }

    public TreeNode Add(string key, string text, string imageKey)
    {
        return NodeCollection.Add(key, text, imageKey);
    }

    public TreeNode Add(string key, string text, int imageIndex, int selectedImageIndex)
    {
        return NodeCollection.Add(key, text, imageIndex, selectedImageIndex);
    }

    public TreeNode Add(string key, string text, string imageKey, string selectedImageKey)
    {
        return NodeCollection.Add(key, text, imageKey, selectedImageKey);
    }

    public void AddRange(TreeNode[] nodes)
    {
        NodeCollection.AddRange(nodes);
    }

    public ParallelQuery AsParallel()
    {
        return NodeCollection.AsParallel();
    }

    public IQueryable AsQueryable()
    {
        return NodeCollection.AsQueryable();
    }

    public IEnumerable<TResult> Cast<TResult>()
    {
        return NodeCollection.Cast<TResult>();
    }

    public void Clear()
    {
        NodeCollection.Clear();
    }

    public bool Contains(TreeNode node)
    {
        return NodeCollection.Contains(node);
    }

    public bool ContainsKey(string key)
    {
        return NodeCollection.ContainsKey(key);
    }

    public void CopyTo(Array dest, int index)
    {
        NodeCollection.CopyTo(dest, index);
    }

    public int Count
    {
        get
        {
            return NodeCollection.Count;
        }
        private set { }
    }

    public bool Equals(object obj)
    {
        return NodeCollection.Equals(obj);
    }

    public TreeNode[] Finde(string key, bool searchAllChildren)
    {
        return NodeCollection.Find(key, searchAllChildren);
    }

    public IEnumerator GetEnumerator()
    {
        return NodeCollection.GetEnumerator();
    }

    public int GetHashCode()
    {
        return NodeCollection.GetHashCode();
    }

    public Type GetType()
    {
        return NodeCollection.GetType();
    }

    public int IndexOf(TreeNode node)
    {
        return NodeCollection.IndexOf(node);
    }

    public int IndexOfKey(string key)
    {
        return NodeCollection.IndexOfKey(key);
    }

    public TreeNode Insert(int index, string text)
    {
        return NodeCollection.Insert(index, text);
    }

    public void Insert(int index, TreeNode node)
    {
        NodeCollection.Insert(index, node);
    }

    public TreeNode Insert(int index,string key, string text)
    {
        return NodeCollection.Insert(index, key, text);
    }

    public TreeNode Insert(int index, string key, string text,int imageIndex)
    {
        return NodeCollection.Insert(index, key, text, imageIndex);
    }

    public TreeNode Insert(int index, string key, string text, string imageKey)
    {
        return NodeCollection.Insert(index, key, text, imageKey);
    }

    public TreeNode Insert(int index, string key, string text, int imageIndex, int selectedImageIndex)
    {
        return NodeCollection.Insert(index, key, text, imageIndex, selectedImageIndex);
    }

    public TreeNode Insert(int index, string key, string text, string imageKey, string selectedImageKey)
    {
        return NodeCollection.Insert(index, key, text, imageKey, selectedImageKey);
    }

    public bool IsReadyOnly
    {
        get
        {
            return NodeCollection.IsReadOnly;
        }
        private set
        {
        }
    }

    public IEnumerable<TResult> OfType<TResult>()
    {
        return NodeCollection.OfType<TResult>();
    }

    public void Remove(TreeNode node)
    {
        NodeCollection.Remove(node);
    }

    public void RemoveAt(int index)
    {
        NodeCollection.RemoveAt(index);
    }

    public void RemoveByKey(string key)
    {
        NodeCollection.RemoveByKey(key);
    }

    public string ToString()
    {
        return NodeCollection.ToString();
    }
}

---

class UGTreeNodeCollection { private TreeNodeCollection NodeCollection;

    public UGTreeNodeCollection(TreeNodeCollection TreeNodeCollectionItem)
    {
        NodeCollection = TreeNodeCollectionItem;
    }

    public TreeNode Add(string text)
    {
        return NodeCollection.Add(text);
    }

    public int Add(TreeNode node)
    {
        return NodeCollection.Add(node);
    }

    public TreeNode Add(string key, string text)
    {
        return NodeCollection.Add(key, text) as TreeNode;
    }

    public TreeNode Add(string key, string text, int imageIndex)
    {
        return NodeCollection.Add(key, text, imageIndex);
    }

    public TreeNode Add(string key, string text, string imageKey)
    {
        return NodeCollection.Add(key, text, imageKey);
    }

    public TreeNode Add(string key, string text, int imageIndex, int selectedImageIndex)
    {
        return NodeCollection.Add(key, text, imageIndex, selectedImageIndex);
    }

    public TreeNode Add(string key, string text, string imageKey, string selectedImageKey)
    {
        return NodeCollection.Add(key, text, imageKey, selectedImageKey);
    }

    public void AddRange(TreeNode[] nodes)
    {
        NodeCollection.AddRange(nodes);
    }

    public ParallelQuery AsParallel()
    {
        return NodeCollection.AsParallel();
    }

    public IQueryable AsQueryable()
    {
        return NodeCollection.AsQueryable();
    }

    public IEnumerable<TResult> Cast<TResult>()
    {
        return NodeCollection.Cast<TResult>();
    }

    public void Clear()
    {
        NodeCollection.Clear();
    }

    public bool Contains(TreeNode node)
    {
        return NodeCollection.Contains(node);
    }

    public bool ContainsKey(string key)
    {
        return NodeCollection.ContainsKey(key);
    }

    public void CopyTo(Array dest, int index)
    {
        NodeCollection.CopyTo(dest, index);
    }

    public int Count
    {
        get
        {
            return NodeCollection.Count;
        }
        private set { }
    }

    public bool Equals(object obj)
    {
        return NodeCollection.Equals(obj);
    }

    public TreeNode[] Finde(string key, bool searchAllChildren)
    {
        return NodeCollection.Find(key, searchAllChildren);
    }

    public IEnumerator GetEnumerator()
    {
        return NodeCollection.GetEnumerator();
    }

    public int GetHashCode()
    {
        return NodeCollection.GetHashCode();
    }

    public Type GetType()
    {
        return NodeCollection.GetType();
    }

    public int IndexOf(TreeNode node)
    {
        return NodeCollection.IndexOf(node);
    }

    public int IndexOfKey(string key)
    {
        return NodeCollection.IndexOfKey(key);
    }

    public TreeNode Insert(int index, string text)
    {
        return NodeCollection.Insert(index, text);
    }

    public void Insert(int index, TreeNode node)
    {
        NodeCollection.Insert(index, node);
    }

    public TreeNode Insert(int index,string key, string text)
    {
        return NodeCollection.Insert(index, key, text);
    }

    public TreeNode Insert(int index, string key, string text,int imageIndex)
    {
        return NodeCollection.Insert(index, key, text, imageIndex);
    }

    public TreeNode Insert(int index, string key, string text, string imageKey)
    {
        return NodeCollection.Insert(index, key, text, imageKey);
    }

    public TreeNode Insert(int index, string key, string text, int imageIndex, int selectedImageIndex)
    {
        return NodeCollection.Insert(index, key, text, imageIndex, selectedImageIndex);
    }

    public TreeNode Insert(int index, string key, string text, string imageKey, string selectedImageKey)
    {
        return NodeCollection.Insert(index, key, text, imageKey, selectedImageKey);
    }

    public bool IsReadyOnly
    {
        get
        {
            return NodeCollection.IsReadOnly;
        }
        private set
        {
        }
    }

    public IEnumerable<TResult> OfType<TResult>()
    {
        return NodeCollection.OfType<TResult>();
    }

    public void Remove(TreeNode node)
    {
        NodeCollection.Remove(node);
    }

    public void RemoveAt(int index)
    {
        NodeCollection.RemoveAt(index);
    }

    public void RemoveByKey(string key)
    {
        NodeCollection.RemoveByKey(key);
    }

    public string ToString()
    {
        return NodeCollection.ToString();
    }
}