自动更新一个组合框，当第一个组合框中获取一定的价值

问题描述

我有两个组合框。我在插入第一个组合框中一个值，现在我想，我的第二个组合框更新根据第一个它的价值。我应该怎么做呢？

I have two combo boxes. I insert one value in first combo box and now i want that my second combo box updates its value according to first one. How should i do that?

推荐答案

在处理的事件的第一个组合框，然后更新基于该第一个组合框值。

Handle the SelectedIndexChanged event for the first ComboBox, then update the second combo box based on the SelectedItem value for the first ComboBox.

一个简单的例子（没有错误处理检索的SelectedItem时）：

A quick example (sans error handling when retrieving the SelectedItem):

public partial class Form1 : Form
{
    private string[] comboBox1Range = new[] { "A", "B", "C", "D" };
    private string[] comboBox2RangeA = new[] { "A1", "A2", "A3", "A4" };
    private string[] comboBox2RangeB = new[] { "B1", "B2", "B3", "B4" };
    private string[] comboBox2RangeC = new[] { "C1", "C2", "C3", "C4" };
    private string[] comboBox2RangeD = new[] { "D1", "D2", "D3", "D4" };

    public Form1()
    {
        InitializeComponent();
        comboBox1.SelectedIndexChanged += comboBox1_SelectedIndexChanged;
        comboBox1.Items.AddRange(comboBox1Range);
    }

    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string selectedValue = comboBox1.SelectedItem as string;

        switch (selectedValue)
        {
            case "A":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeA);
                break;
            case "B":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeB);
                break;
            case "C":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeC);
                break;
            case "D":
                comboBox2.Items.Clear();
                comboBox2.Items.AddRange(comboBox2RangeD);
                break;
        }
    }
}

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