GraphicsCreator().FillEllipse处的StackOverflow异常

Question

当我不是只填充一个椭圆，而是填充多个椭圆时，我会得到一个堆栈溢出异常。

我不认为这是图形创建者的问题。但是我不明白为什么调试器将堆栈溢出异常指向FillEllipse命令

    public void createPath(Stance currentStance)
    {

        if(toSort.Count > 0)
        {
            toSort.Remove(currentStance);
            counter++;
        }

        this.currentForm.FillEllipse(new SolidBrush(Color.Red),new Rectangle(currentStance.location.X-3, currentStance.location.Y - 3, 6 , 6));

        foreach(Stance subStance in currentStance.childStances)
        {
            double weight = level(currentStance, subStance, 1)+ currentStance.StanceWeight;
            if (subStance.StanceWeight == -99999999999999)
            {
                currentStance.dajkstrasChildren.Add(subStance);
                subStance.parentStance = currentStance;
                subStance.StanceWeight = weight;
                toSort.Add(subStance);
            }
            else
            {
                if(weight > subStance.StanceWeight)
                {
                    try
                    {
                        subStance.parentStance.dajkstrasChildren.Remove(subStance);
                    }
                    catch (NullReferenceException e)
                    {
                        Console.WriteLine("null reference");
                    }
                    subStance.parentStance = currentStance;
                    currentStance.dajkstrasChildren.Add(subStance);
                    subStance.StanceWeight = weight;

                }
            }
        }

        foreach(Stance subStance in currentStance.secondChildStances)
        {         
            double weight = level(currentStance, subStance, 1) + currentStance.StanceWeight;
            if (subStance.StanceWeight == -99999999999999)
            {
                currentStance.dajkstrasChildren.Add(subStance);
                subStance.parentStance = currentStance;
                toSort.Add(subStance);
                subStance.StanceWeight = weight;
            }
            else
            {
                if (weight > subStance.StanceWeight)
                {   
                    if(subStance.parentStance != null)
                    {
                        try
                        {
                            subStance.parentStance.dajkstrasChildren.Remove(subStance);
                            subStance.parentStance = currentStance;
                            currentStance.dajkstrasChildren.Add(subStance);
                        }
                        catch(NullReferenceException e)
                        {
                            Console.WriteLine("null reference");
                        }
                    }

                }
            }
        }

        toSort.Sort(new Stance());
        if(toSort.Count != 0)
        {
            createPath((Stance)toSort[0]);
        }
    }

它是一个递归方法，但它不能递归到无穷大，因为它总是从toSort ArrayList中弹出一个对象

Answer 1

这是因为在尝试调用FillEllipse时，堆栈实际上会用完。

当然，堆栈溢出必须是由您的逻辑中的一个缺陷引起的，该缺陷导致您的createPath方法被无限期地递归调用，或者被调用得太深，以至于堆栈无法容纳所有需要的激活帧。

Answer 2

使用while循环而不是递归，以避免加载堆栈。

以下是修改后的代码，可能会起作用：

public void createPath(Stance stance)
    {
        var currentStance = stance;

        while(toSort.Count >0)
        {
            toSort.Remove(currentStance);
            counter++;


        this.currentForm.FillEllipse(new SolidBrush(Color.Red),new Rectangle(currentStance.location.X-3, currentStance.location.Y - 3, 6 , 6));

        foreach(Stance subStance in currentStance.childStances)
        {
            double weight = level(currentStance, subStance, 1)+ currentStance.StanceWeight;
            if (subStance.StanceWeight == -99999999999999)
            {
                currentStance.dajkstrasChildren.Add(subStance);
                subStance.parentStance = currentStance;
                subStance.StanceWeight = weight;
                toSort.Add(subStance);
            }
            else
            {
                if(weight > subStance.StanceWeight)
                {
                    try
                    {
                        subStance.parentStance.dajkstrasChildren.Remove(subStance);
                    }
                    catch (NullReferenceException e)
                    {
                        Console.WriteLine("null reference");
                    }
                    subStance.parentStance = currentStance;
                    currentStance.dajkstrasChildren.Add(subStance);
                    subStance.StanceWeight = weight;

                }
            }
        }

        foreach(Stance subStance in currentStance.secondChildStances)
        {         
            double weight = level(currentStance, subStance, 1) + currentStance.StanceWeight;
            if (subStance.StanceWeight == -99999999999999)
            {
                currentStance.dajkstrasChildren.Add(subStance);
                subStance.parentStance = currentStance;
                toSort.Add(subStance);
                subStance.StanceWeight = weight;
            }
            else
            {
                if (weight > subStance.StanceWeight)
                {   
                    if(subStance.parentStance != null)
                    {
                        try
                        {
                            subStance.parentStance.dajkstrasChildren.Remove(subStance);
                            subStance.parentStance = currentStance;
                            currentStance.dajkstrasChildren.Add(subStance);
                        }
                        catch(NullReferenceException e)
                        {
                            Console.WriteLine("null reference");
                        }
                    }

                }
            }
        }

        toSort.Sort(new Stance());
        currentStance = (Stance)toSort[0];
      }
    }