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ComboBox.BeginUpdate Method

.NET Framework 4

Other Versions

Maintains performance when items are added to the ComboBox one at a time.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)

Syntax

C++

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public void BeginUpdate()

Remarks

This method prevents the control from painting until the EndUpdate method is called.

The preferred way to add items to the ComboBox is to use the AddRange method of the ComboBox.ObjectCollection class (through the Items property of the ComboBox). This enables you to add an array of items to the list at one time. However, if you want to add items one at a time using the Add method of the ComboBox.ObjectCollection class, you can use the BeginUpdate method to prevent the control from repainting the ComboBox each time an item is added to the list. Once you have completed the task of adding items to the list, call the EndUpdate method to enable the ComboBox to repaint. This way of adding items can prevent flicker during the drawing of the ComboBox when a large number of items are being added to the list.

Examples

The following code example shows the usage of the BeginUpdate and EndUpdate methods. The example is part of a complete code example in the ComboBox class overview.

C++

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private void addGrandButton_Click(object sender, System.EventArgs e) {
    comboBox1.BeginUpdate();
    for (int i = 0; i < 1000; i++) {
        comboBox1.Items.Add("New Item " + i.ToString());
    }
    comboBox1.EndUpdate();
}

Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference

ComboBox Class

System.Windows.Forms Namespace

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