获取ComboBox的先前值 [英] Getting previous value of the ComboBox

问题描述

我希望我的应用程序获取ComboBox的值，然后设置用户选择的ComboBox或以某种方式获取先前选择的值.

I want my application to grab the value of a ComboBox and then to set the one chosen by the user or to somehow get the previously selected value.

问题是，在我的表单中，有四个列表和一个ComboBox(其中包含列表中的所有值)，我想将ComboBox的值重新填充回它来自的列表，然后删除其他/相同列表中新选择的项目.

The thing is that within my Form, there are four lists and a ComboBox (which contains all the values from the lists) and I want to repopulate the value of the ComboBox back to the list it was taken from and then remove the newly selected item from other/same list.

推荐答案

您要处理 SelectedItem 或 SelectedValue 到成员变量.然后，无论何时需要，您都可以将该值重新分配给ComboBox.

You want to handle the ComboBox.Enter event. Then save off the SelectedItem or SelectedValue to a member variable. Whenever you want then, you can re-assign that value to the ComboBox.

注册活动.您可以通过以下两种方式之一进行操作:

Register for the event. You can do this one of two ways:

通过设计器完成.选择您的组合框.在属性窗口"中，单击闪电图标以显示其所有事件.然后找到"Enter"，然后在框中双击.它将自动为您生成回调函数(事件处理程序")，并将其连接到事件.

Do it through the designer. Select your combo box. In the "Properties window", click the lightning bolt icon to show all of its events. Then find "Enter", and double-click in the box. It will automatically generate the callback function ("event handler") for you, and wire it up to the event.

您可以通过编程方式执行相同的操作.在构造函数中，连接具有正确签名的事件处理程序:

You can programatically do the same thing. In the constructor, hook up an event handler of the correct signature:

public partial class Form1 : Form 
{
    public Form1()
    {
        InitializeComponent();
        comboBox1.Enter += comboBox1_Enter;
    }

    private void comboBox1_Enter(object sender, EventArgs e)
    {
        m_cb1PrevVal = comboBox1.SelectedValue;
    }

    private void RestoreOldValue()
    {
        comboBox1.SelectedValue = m_cb1PrevVal;
    }
}

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