HashSet<T>.Clear 方法
定义
重要
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从 HashSet<T> 对象中移除所有元素。
public:
virtual void Clear();public void Clear ();abstract member Clear : unit -> unit
override this.Clear : unit -> unitPublic Sub Clear ()实现
示例
以下示例创建并填充 HashSet<T> 集合，然后清除该集合并释放该集合引用的内存。
HashSet<int> Numbers = new HashSet<int>();
for (int i = 0; i < 10; i++)
{
Numbers.Add(i);
}
Console.Write("Numbers contains {0} elements: ", Numbers.Count);
DisplaySet(Numbers);
Numbers.Clear();
Numbers.TrimExcess();
Console.Write("Numbers contains {0} elements: ", Numbers.Count);
DisplaySet(Numbers);
void DisplaySet(HashSet<int> set)
{
Console.Write("{");
foreach (int i in set)
{
Console.Write(" {0}", i);
}
Console.WriteLine(" }");
}
/* This example produces output similar to the following:
* Numbers contains 10 elements: { 0 1 2 3 4 5 6 7 8 9 }
* Numbers contains 0 elements: { }
*/
Imports System.Collections.Generic
Class Program
Shared Sub Main()
Dim Numbers As HashSet(Of Integer) = New HashSet(Of Integer)()
For i As Integer = 0 To 9
Numbers.Add(i)
Next i
Console.Write("Numbers contains {0} elements: ", Numbers.Count)
DisplaySet(Numbers)
Numbers.Clear()
Numbers.TrimExcess()
Console.Write("Numbers contains {0} elements: ", Numbers.Count)
DisplaySet(Numbers)
End Sub
' This code example produces output similar to the following:
' Numbers contains 10 elements: { 0 1 2 3 4 5 6 7 8 9 }
' Numbers contains 0 elements: { }
Private Shared Sub DisplaySet(ByVal coll As HashSet(Of Integer))
Console.Write("{")
For Each i As Integer In coll
Console.Write(" {0}", i)
Next i
Console.WriteLine(" }")
End Sub
End Class
注解
Count 设置为零，并且也会释放对集合元素中其他对象的引用。 在调用 TrimExcess 之前，容量保持不变。
此方法是 O (n) 操作，其中 n 为 Count。
