無法將現有的PictureBox對象分配給對象數組

我正試圖解決一本書的練習。（沒有已發佈的答案）無法將現有的PictureBox對象分配給對象數組

我需要將我的窗體上存在的PictureBox對象引用到對象數組。（我需要分配其中的四個）

我初始化數組並將變量賦值給它。然後，我調用數組中的每個項目中的方法，但PictureBox對象未分配。（空例外）

我有點困惑，因爲我在網上公開了代碼片段，顯示我正確地做了這件事。

下面的代碼爲指針，請：

主類

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(); 
     } 
    } 
}

灰狗類

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() 
    { } 
}

而且我可以證實每條狗的PictureBox並在表格上存在：

片段來自Form1.Designer.cs

// 
// 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;

來源

2012-07-04 Damo

它是InitializeComponent，初始化dog1，dog2等的值。所以先調用* first *，然後初始化你的數組。練習使用調試器，當你看着greyhoundArray時很容易看到。 –

在GreyHound數組初始化之前調用InitializeComponent()。

當你調用灰狗陣列的初始化，您還沒有叫裏面的InitializeComponent的this.dog1 = new PictureBox()，所以你複製一個空到每個灰狗實例

同樣的MyPictureBox財產，我認爲你有一個問題您的灰狗類中的Randomiser變量

來源

2012-07-04 21:30:32 Steve

當然。我猜這些圖畫框在它們沒有活力之前是不存在的。 – Damo

謝謝，你有沒有試過Run方法？這對於每個對象來說都是隨機的，還是一樣的？ – Steve

我現在正在努力，所有'狗'都以相同的速度移動。確實是一項進展中的工作。 – Damo

-1

您無法訪問窗體構造函數中的窗體控件。您需要在Form_Load事件處理程序中初始化您的灰狗的圖片框。

來源

2012-07-04 21:27:37 ekolis

在聲明數組中的任何內容之前，您應該初始化表單的控件，也就是說，因爲您的數組正在引用表單中的項目。

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 
      }, 
     } 
    }

來源

2012-07-04 21:34:40 jp2code

無法將現有的PictureBox對象分配給對象數組

回答

相關問題