Question

我有一个C＃Winform应用程序。它有一个ComboBox。我的目标是在输入ComboBox键时，ComboBox下拉列表中选中的项目会显示在delete的可编辑部分中。例如，如果ComboBox包含商品A，B。和C，然后在加载A时显示项Form。如果我点击下拉菜单，将鼠标悬停在项C上，然后输入delete键，我希望下拉列表被删除，C出现在该项目的可编辑部分ComboBox。

实际上，我已经确认我收到了所选的项目文字，但代码行comboBox.SelectedIndex = comboBox.FindStringExact(selectedItemText);并未更改ComboBox的可编辑部分中显示的内容

MCVE：

注意：表单有一个名为combobox的组合框和一个名为textbox的文本框

using System.Collections;
using System.Collections.Specialized;
using System.Windows.Forms;

namespace Winforms_Scratch
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            //using string collection because I need to simulate what is returned from an Application Settings list
            StringCollection computerList = new StringCollection { "C", "B", "A" };

            ArrayList.Adapter(computerList).Sort();

            comboBox.DataSource = computerList;

            comboBox.KeyDown += ComboBox_KeyDown;

            computerList = null;

        }

        private void ComboBox_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Delete && comboBox.DroppedDown)
            {
                ComboBox comboBox = (ComboBox)sender;

                //get the text of the item in the dropdown that was selected when the Delete key was pressed
                string selectedItemText = comboBox.GetItemText(comboBox.SelectedItem);

                //take focus away from the combobox to force it to dismiss the dropdown
                this.Focus();

                //load selectedItemText into the textbox just so we can verify what it is
                textBox.Text = selectedItemText;

                //set the comboBox SelectedIndex to the index of the item that matches the  
                //text of the item in the dropdown that was selected when the Delete key was pressed
                comboBox.SelectedIndex = comboBox.FindStringExact(selectedItemText);
                comboBox.Refresh();

                //Stop all further processing
                e.Handled = true;

            }
            else if (e.KeyCode == Keys.Down && !comboBox.DroppedDown)
            {
                //If the down arrow is pressed show the dropdown list from the combobox
                comboBox.DroppedDown = true;
            }
        }


    }
}

Answer 1

我的猜测是，组合框失去焦点后表现不同。在任何情况下，根据我对您的要求的理解，我做了以下更改并且它有效。您可以在设置所选项目后调用this.Focus()，如果有单独的要求将焦点返回到窗口。您的SelectedIndex / FindStringExact方法与将SelectedItem设置为字符串的工作方式相同。

我摆脱了文本框，因为我理解它仅用于调试目的。

private void ComboBox_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Delete && comboBox.DroppedDown)
    {
        ComboBox comboBox = (ComboBox)sender;

        //  Get the text of the item in the dropdown that was selected when the 
        //  Delete key was pressed
        string selectedItemText = comboBox.GetItemText(comboBox.SelectedItem);

        comboBox.DroppedDown = false;

        comboBox.SelectedItem = selectedItemText;

        //Stop all further processing
        e.Handled = true;

    }
    else if (e.KeyCode == Keys.Down && !comboBox.DroppedDown)
    {
        //  If the down arrow is pressed show the dropdown list from the combobox
        comboBox.DroppedDown = true;
    }
}

为什么设置comboBox.SelectedIndex无法更改我的ComboBox的可编辑部分中显示的内容？

1 个答案: