在文本框中显示组合框选定的项目

Question

Public Class Form1
Public selected As Integer

Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
    Select Case ComboBox1.SelectedItem
        Case "Philippines (PHP)"
            selected = 1.0
        Case "United States(USD)"
            selected = 45.2
        Case "Japan(JPY)"
            selected = 0.36
        Case "Canada(CAD)"
            selected = 35.01
        Case "Australia(AUD)"
            selected = 33.34
    End Select
End Sub

Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
    TextBox1.Text = ComboBox1.SelectedItem
End Sub
End Class

大家别笑我只是随便看VS2010基础教程.. 我的问题是组合框中的所选项目没有显示在文本框中..

Answer 1

1st selected 是一个 int，所以它不能有 1.0、45.2 等值。 2、TextBox1_TextChanged 没有被触发，所以这样尝试：

Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
 ...
 TextBox1.Text = ComboBox1.SelectedItem

Answer 2

这是 C# 代码，但我确信概念是相同的。您的 TextBox1_TextChanged 事件永远不会被触发，因为您从未设置文本框的文本以便可以将其删除，并将该代码移动到您的 comboBox1_SelectedIndexChanged 事件中。

    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        switch (comboBox1.SelectedItem.ToString())
        {
            case "Hey":
                selected = 1;
                break;
            case "There":
                selected  = 2;
                break;
            case "You":
                selected  = 33.34;
                break;
        }
        textBox1.Text = ComboBox1.SelectedItem.ToString();
    }

Answer 3

首先，您的 'selected' 变量类型错误。它需要是字符串或双精度类型。如果只是为了提高可读性，则为 String；如果打算在计算中使用，则为 double。

Public selected As Double

Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
    ' Call the ToString() method to get the text.
    Select Case ComboBox1.SelectedItem.ToString()
        Case "Philippines (PHP)"
            selected = 1.0
        Case "United States(USD)"
            selected = 45.2
        Case "Japan(JPY)"
            selected = 0.36
        Case "Canada(CAD)"
            selected = 35.01
        Case "Australia(AUD)"
            selected = 33.34
    End Select
    ' You need to catch if the selected variable has not value set.
    Textbox1.Text = selected.ToString()
End Sub

在文本框中显示组合框选定的项目

Show Combobox selected item in textbox

vb.net

combobox

selecteditem

visual-studio-2010