在C＃中的comboBox中初始化一个值

Question

I realize that my comboBox is always empty when program start. I have to click the arrow beside to choose a value. How do we do it so that the comboBox will show a value when the program start?

Answer 1

There are the following 4 properties that you can set:

// Gets or sets the index specifying the currently selected item.
comboBox1.SelectedIndex = someIndex;  //int

// Gets or sets currently selected item in the ComboBox.
comboBox1.SelectedItem = someItem; // object

// Gets or sets the text that is selected in the editable portion of a ComboBox.
comboBox1.SelectedText = someItemText; // string

// Gets or sets the value of the member property specified by the ValueMember property. 
comboBox1.SelectedValue = someValue; // object

Comment lines straight from MSDN: http://msdn.microsoft.com/en-us/library/system.windows.forms.combobox.aspx

Answer 2

If you have a combo box and want to set it's Data Source you may do it like this:

 string[] items = new string[]{"Ram","Shyam"};
    comboBox1.DataSource = items;
    comboBox1.SelectedIndex = 0;

So try to set the SelectedIndex to first index.

Answer 3

试试这段代码：

comboBox1.Items.Add("Test");

Answer 4

Davenewza's answer is great for the programmatic approach (Which I highly recommend). Another way that is less elegant but utilizes the properties toolbox is to do the following:

1. From the design view, click the comboBox in question.
2. Navigate to Appearance->Text and enter any string you wish.

To be safe, I would enter a value that corresponds to something that will be selected in the box to prevent unwanted strings from being propagated to other functions/variables. This reason can cause a lot of headaches if not carefully handled, which is why the programmatic approach is preferred.

Answer 5

If you are using WPF with MVVM and INotifyPropertiesChanged interface, then you can set a fallback value in your binding property. SelectedIndex="{Binding SelectedCountry.MultipleClassCountry, FallbackValue= 0}" Setting SelectedIndex = 0 should select the first Item you have in your combobox.