运行时的StackOverflow异常

Question

运行此代码时出现异常。

public void insertRBT(int value)
        {
            //BNode newNode = new BNode(value);
            root=insertNode(root, value,null);
            count += 1;
        }

        protected BNode insertNode(BNode rt, int value, BNode parent)
        {
            BNode grandParent, greatGrandParent;
            if (rt == null)
            {

                BNode newNode = new BNode(value, parent);
                parent = newNode.parent;
                if (parent != null)
                {
                    if (value > parent.value)
                    {
                        parent.right = newNode;
                    }
                    else {
                        parent.left = newNode;
                    }
                }
                if (count > 0)
                {
                    newNode.red = true;
                }
                else
                {
                    newNode.red = false;
                }
                //added

                insertedNode = newNode;
                grandParent = null;
                greatGrandParent = null;
                insertFix(newNode,parent,grandParent,greatGrandParent);
                return newNode;
            }
            else if (value.CompareTo(rt.value) < 0)
            {
                rt.left = insertNode(rt.left, value, rt);
                return rt;
            }else //if(value.CompareTo(rt.value)> 0)
            {
                rt.right = insertNode(rt.right, value, rt);
                return rt;
            }
}

当我添加以下代码时，错误开始出现：

if (parent != null)
{
    if (value > parent.value)
    {
        parent.right = newNode;
    }
    else {
       parent.left = newNode;
     }
}

// BNode类

class BNode
    {
        public int value;
        public BNode left;
        public BNode right;
        public BNode parent; //check
        public Boolean red = true; // red=false - indicates black

        public BNode(int num, BNode parent)
        {
            value = num;
            left = null;
            right = null;
            this.parent = parent;
        }
}

在测试代码后，我添加了50,75,40,45,25 - 当我输入25时，发生了异常。