Question

我正在使用C＃.net中的Windows窗体。我在表单上有2 ComboBox和3 TextBox。当我更改ComboBox1中的值时（通过与UI中的项目进行交互），它会更改ComboBox2中的项目和所选项目。

当所选的ComboBox2索引发生更改时，应该更改所有TextBox中的文字，但似乎SelectedIndexChanged不是被解雇了。

public void comboSelectionChanged(object sender, EventArgs e)
    {
        //when the selection changes...
        // 1) cast the sender as a comboBox
        ComboBox cBox = (ComboBox)sender;

        // 2) identify the sender
        if (cBox.Name.ToString() == "ComboBox1")
        {   //this is the 1st combo box                

            //load the children of the new selection into the form
            //child of ComboBox1 is ComboBox2
            ComboBox2.Items.Clear();
            ComboBox2.Text = null;
            string selected = null;

            foreach (string item in {"box2_item1","box2_item2"})
            {
                ComboBox2.Items.Add(item);
            }
            //need to set the selection last, because this will (hopefully) fire the selection changed event on the child

            if (selected != null)
            {//here I am actually getting the selected item from XML
                ComboBox2.SelectedItem = selected;
            }
            else
            {//this should be action that is initiated, which should definitely change the selected index
                ComboBox2.SelectedIndex = -1;
            }
        }
        else if (cBox.Name.ToString() == "ComboBox2")
        {   //this is the 2nd combobox              

            //load the children of the new selection into the form
            //the textBoxes are the children
            TextBox1.Text = "some new text that I am getting from XML";
            TextBox2.Text = "some other new text as above.";
            TextBox3.Text = "same thing, one more time" ;
        }
        else
        {   //I messed something up, because the combobox name is invalid
            Debug.Write("Unreachable code encountered: The combobox name {" + cBox.Name.ToString() + "} is not valid!");
            return;
        }

我试图简化这一点，希望我没有通过简化来过度使用它。如上所述，我从XML文件获取数据，理想情况下的目标是使用此表单来读取和写入XML文件。在我看来，所有的XML工作正常，所以我把所有这些都留下了。

两个方框＆＃39; SelectedIndexChanged个事件与上面的代码相关联。会发生什么变化是当我更改ComboBox1的值时ComboBox2的值被更改，并且所选项目被清除，但ComboBox2.SeletedIndexChanged事件永远不会被触发（breakpoins告诉我代码永远不会重新输入时钟），因此TextBox没有更新新数据。

我希望一切都有道理，而且somone可以帮助我弄清楚我做错了什么。

Answer 1

事件处理程序只是一种方法，因此您可以调用它。如果您的处理程序名为ComboBox2_SelectedIndexChanged，则可以执行以下操作：

        ...
        else
        {//this should be action that is initiated, which should definitely change the selected index
            ComboBox2.SelectedIndex = -1;
            ComboBox2_SelectedIndexChanged(ComboBox2, new EventArgs());
        }
        ...

Answer 2

通过调用

在comboSelectionChanged(object sender, EventArgs e)方法中通过自己触发SelectedIndexChanged事件

ComboBox2_SelectedIndexChanged(ComboBox2, new EventArgs());

以编程方式更改索引时，不会触发ComboBox.SelectedIndexChanged

2 个答案: