从列表中删除C＃对象会丢失引用

Question

I have a very strange issue. Basically I have created a class called TreeNode that represents a node in a tree. I then create the tree by adding all the nodes to a List.

class TreeNode
{

    private TreeNode parent, lChild, rChild;
    private int key, val;

    public int Key
    {
        get { return key; }
        set { key = value; }
    }
    public int Val
    {
        get { return val; }
        set { val = value; }
    }

    public TreeNode Parent
    {
        get { return parent; }
        set { parent = value; }
    }
    public TreeNode LChild
    {
        get { return lChild; }
    }
    public TreeNode RChild
    {
        get { return rChild; }
    }

    public TreeNode(int k, int v)
    {
        key = k;
        val = v;
    }

    public void SetChild(TreeNode leftChild, TreeNode rightChild)
    {
        this.lChild = leftChild;
        this.rChild = rightChild;

    }

    public bool isLeaf()
    {
        if (this.lChild == null && this.rChild == null) 
        {
            return true;
        } else 
        {
            return false;
        }
    }

    public bool isParent()
    {
        if (this.parent == null)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public void SetParent(TreeNode Parent)
    {
        this.parent = Parent;
    }
}

So if i put a breakpoint just after the creation of the tree and hover over the list in Visual Studio I can see the structure of the tree - with all the references working perfectly from the root down to the leaves.

If however I do the following:

TreeNode test = newTree[newTree.Count - 1];

please note:

private List<TreeNode> newTree = new List<TreeNode>();

which returns the root node - and hover over again I can do down one level (ie left child or right child) but these children do not have any references for their children after that.

I'm wondering if I'm losing the reference in memory to the other nodes in the list as the test node is not part of the list?

Any help would be greatly appreciated.

Thanks Tom

Answer 1

you sure you don't have (note no space between new and tree in your code)

TreeNode test = new Tree[newTree.Count - 1]; 

Which would create a new empty array of tree (probably not what you intended), and leave your original tree un-rooted and inaccessible.

Can you make sure your code is correct, please?

Answer 2

Seems as though I found the issue - I wasn't correctly updating some of the parent nodes with their relevant child nodes - problem solved.

Thanks for your help Tom