CollectionChangeEventArgs.Action 属性
定义
获取指定集合如何更改的操作。Gets an action that specifies how the collection changed.
public:
virtual property System::ComponentModel::CollectionChangeAction Action { System::ComponentModel::CollectionChangeAction get(); };
public virtual System.ComponentModel.CollectionChangeAction Action { get; }
member this.Action : System.ComponentModel.CollectionChangeAction
Public Overridable ReadOnly Property Action As CollectionChangeAction
属性值
CollectionChangeAction 值之一。One of the CollectionChangeAction values.
示例
下面的代码示例演示如何使用此成员。The following code example demonstrates the use of this member. 在此示例中,事件处理程序报告事件的发生 AutoCompleteStringCollection.CollectionChanged 。In the example, an event handler reports on the occurrence of the AutoCompleteStringCollection.CollectionChanged event. 此报表可帮助你了解何时发生事件,并可帮助你进行调试。This report helps you to learn when the event occurs and can assist you in debugging. 若要报告多个事件或频繁发生的事件,请考虑 MessageBox.Show Console.WriteLine 将消息替换为多行或将其追加到多行 TextBox 。To report on multiple events or on events that occur frequently, consider replacing MessageBox.Show with Console.WriteLine or appending the message to a multiline TextBox.
若要运行示例代码,请将其粘贴到包含名为的类型的实例的项目中 AutoCompleteStringCollection AutoCompleteStringCollection1 。To run the example code, paste it into a project that contains an instance of type AutoCompleteStringCollection named AutoCompleteStringCollection1. 然后,确保事件处理程序与事件相关联 AutoCompleteStringCollection.CollectionChanged 。Then ensure that the event handler is associated with the AutoCompleteStringCollection.CollectionChanged event.
private void AutoCompleteStringCollection1_CollectionChanged(Object sender, CollectionChangeEventArgs e) {
System.Text.StringBuilder messageBoxCS = new System.Text.StringBuilder();
messageBoxCS.AppendFormat("{0} = {1}", "Action", e.Action );
messageBoxCS.AppendLine();
messageBoxCS.AppendFormat("{0} = {1}", "Element", e.Element );
messageBoxCS.AppendLine();
MessageBox.Show(messageBoxCS.ToString(), "CollectionChanged Event" );
}
Private Sub AutoCompleteStringCollection1_CollectionChanged(sender as Object, e as CollectionChangeEventArgs) _
Handles AutoCompleteStringCollection1.CollectionChanged
Dim messageBoxVB as New System.Text.StringBuilder()
messageBoxVB.AppendFormat("{0} = {1}", "Action", e.Action)
messageBoxVB.AppendLine()
messageBoxVB.AppendFormat("{0} = {1}", "Element", e.Element)
messageBoxVB.AppendLine()
MessageBox.Show(messageBoxVB.ToString(),"CollectionChanged Event")
End Sub
注解
此属性可以具有下列值之一:This property can have one of the following values:
| 操作Action | 属性值Property value |
|---|---|
| 元素已添加到集合中An element was added to the collection | CollectionChangeAction.Add |
| 已从集合中移除元素An element was removed from the collection | CollectionChangeAction.Remove |
| 集合已完全更改The collection was completely changed | CollectionChangeAction.Refresh |