Question

我的问题是，我无法将值写入文本框对象。以下是创建文本框的代码部分：

int number = 10;

TextBox[,] arrayTextBoxenHochpunkte= new TextBox[10,3];
for(int i=0; i<number; i++)
{
    TextBox newTextBox = new TextBox();
    newTextBox.Location = new Point(0, (3+(i * 25)));
    newTextBox.Size = new Size(25, 26);
    newTextBox.Text = "H" + Convert.ToString(i + 1);
    newTextBox.ReadOnly = true;
    panel1.Controls.Add(newTextBox);

    arrayTextBoxenHochpunkte[i, 0] = newTextBox;

    TextBox newTextBox2 = new TextBox();
    newTextBox2.Location = new Point(28, (3+(i * 25)));
    newTextBox2.Size = new Size(50, 26);
    newTextBox2.ReadOnly = true;
    panel1.Controls.Add(newTextBox2);

    arrayTextBoxenHochpunkte[i, 1] = newTextBox2;

    TextBox newTextBox3 = new TextBox();
    newTextBox3.Location = new Point(83, (3+(i * 25)));
    newTextBox3.Size = new Size(50, 26);
    newTextBox3.ReadOnly = true;
    panel1.Controls.Add(newTextBox3);

    arrayTextBoxenHochpunkte[i, 2] = newTextBox3;
}

以下是应在文本框中写入值的方法：

private void addHochpunkt(float xValue, float yValue)
{
    int i;
    for (i = 0; i < 10; i++)
    {
       if (!(string.IsNullOrWhiteSpace(arrayTextBoxenHochpunkte[i,1].Text)))
       {
         continue;
       }
       arrayTextBoxenHochpunkte[i, 1].Text = "xValue";
       arrayTextBoxenHochpunkte[i, 2].Text = "yValue";
    }
}

我做错了什么？

Answer 1

如果您已全局声明数组TextBox[,] arrayTextBoxenHochpunkte，那么您不会在本地再次声明具有相同名称的数组。以这种方式初始化本地的一个，当你尝试使用全局的那个时，留下全局空触发着名的NullReferenceException

public class Form1 : Form
{
    private TextBox[,] arrayTextBoxenHochpunkte;

    public void SomeMethod()
    {
         int number = 10;
         // This line declares an array with the same name and thus
         // hides the global one declared at the form/class level
         // All your initialization goes into this local one that is
         // lost when you exit from this method..... remove it...
         // TextBox[,] arrayTextBoxenHochpunkte= new TextBox[10,3];

         // This line initializes the global array so it is available 
         // also in other methods.....
         arrayTextBoxenHochpunkte= new TextBox[10,3];
         .....
         initialization code 
         .....

    }

    private void addHochpunkt(float xValue, float yValue)
    {
        int i;
        for (i = 0; i < 10; i++)
        {
           // Here you try to reference the global array, but
           // your current code leaves the global one without initialization
           // thus a NullReferenceException..... 
           if (!(string.IsNullOrWhiteSpace(arrayTextBoxenHochpunkte[i,1].Text)))
           {
             continue;
           }
           // I suppose that you want to write the value 
           // of the two variables not their names.
           arrayTextBoxenHochpunkte[i, 1].Text = xValue.ToString();
           arrayTextBoxenHochpunkte[i, 2].Text = yValue.ToString();
        }
    }
}

在存储在数组中的文本框中写入值

1 个答案: