C# 无法将现有PictureBox对象分配给对象数组

我正试图解决一本书上的练习题。（没有公布答案）

我需要将表单上的PictureBox对象引用到对象数组。（我真的需要分配四个）

我初始化数组并将变量分配给它。然后，我在数组中的每个项中调用一个方法，但是没有指定PictureBox对象。（空异常）

我有点困惑，因为我在网上公开发现了代码片段，这表明我做得很正确

请输入以下代码以获取指针：

主类

public partial class Form1 : Form
{
    Greyhound[] greyhoundArray = new Greyhound[4];

    public Form1()
    {
        greyhoundArray[0] = new Greyhound() { Location = 0, MyPictureBox = dog1, RaceTrackLenght = 100, StartingPosition = 0 };
        greyhoundArray[1] = new Greyhound() { Location = 0, MyPictureBox = dog2, RaceTrackLenght = 100, StartingPosition = 0 };
        greyhoundArray[2] = new Greyhound() { Location = 0, MyPictureBox = dog3, RaceTrackLenght = 100, StartingPosition = 0 };
        greyhoundArray[3] = new Greyhound() { Location = 0, MyPictureBox = dog4, RaceTrackLenght = 100, StartingPosition = 0 };

        InitializeComponent();
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        foreach (Greyhound greyhound in greyhoundArray)
        {
            greyhound.Run();
        }
    }
}

灰狗级

public class Greyhound
{
    public int StartingPosition;
    public int RaceTrackLenght;
    public PictureBox MyPictureBox;
    public int Location = 0;
    public Random Randomiser;

    public void Run()
    {
        // MessageBox.Show(MyPictureBox.Name + " was called");
        Randomiser = new Random();

        int distance = Randomiser.Next(0, 4);

        Point p = MyPictureBox.Location;
        p.X += distance;
        MyPictureBox.Location = p;
    }

    public void TakeStartingPosition()
    { }
}

此外，我可以确认表格上是否存在每个狗图片盒：

Form1.Designer.cs中的代码段

// 
// dog1
// 
this.dog1.Image = ((System.Drawing.Image)(resources.GetObject("dog1.Image")));
this.dog1.Location = new System.Drawing.Point(17, 21);
this.dog1.Name = "dog1";
this.dog1.Size = new System.Drawing.Size(71, 26);
this.dog1.SizeMode = System.Windows.Forms.PictureBoxSizeMode.CenterImage;
this.dog1.TabIndex = 2;
this.dog1.TabStop = false;

---

无法访问窗体构造函数中的窗体控件。您需要在Form\u Load事件处理程序中初始化灰狗的图片框。

在初始化灰狗数组之前调用

InitializeComponent（）

调用灰狗数组的初始化时，尚未调用InitializeComponent内部的

this.dog1=new PictureBox（）

，因此将null复制到每个灰狗实例的

MyPictureBox

属性中

---

另外，我认为您的Greyhound类中的Randomiser变量有问题，您应该在声明数组中的任何内容之前初始化窗体的控件，这是因为数组引用了窗体中的项

    Greyhound[] greyhoundArray;

    public Form1()
    {
        InitializeComponent();
        greyhoundArray = new Greyhound[] {
          new Greyhound() {
            Location = 0,
            MyPictureBox = dog1,
            RaceTrackLenght = 100,
            StartingPosition = 0
          },
          new Greyhound() {
            Location = 0,
            MyPictureBox = dog2,
            RaceTrackLenght = 100,
            StartingPosition = 0
          },
          new Greyhound() {
            Location = 0,
            MyPictureBox = dog3,
            RaceTrackLenght = 100,
            StartingPosition = 0
          },
          new Greyhound() {
            Location = 0,
            MyPictureBox = dog4,
            RaceTrackLenght = 100,
            StartingPosition = 0
          },
       }
    }

---

初始化dog1、dog2等值的是InitializeComponent。所以先调用它，然后初始化数组。练习使用调试器，查看greyhoundArray时很容易看到。我猜PictureBoxs在初始化之前是不存在的。谢谢，你试过Run方法吗？每个物体的下一个值是随机的还是相同的？我现在正在研究，所有的“狗”都以相同的速度移动。这确实是一项正在进行的工作。