Collection<T>.Remove(T) 方法
定义
从 Collection<T> 中移除特定对象的第一个匹配项。Removes the first occurrence of a specific object from the Collection<T>.
public:
virtual bool Remove(T item);
public bool Remove (T item);
abstract member Remove : 'T -> bool
override this.Remove : 'T -> bool
Public Function Remove (item As T) As Boolean
参数
- item
- T
要从 Collection<T> 中删除的对象。The object to remove from the Collection<T>. 对于引用类型,该值可以为 null。The value can be null for reference types.
返回
如果成功移除了 item,则为 true;否则为 false。true if item is successfully removed; otherwise, false. 如果在原始 false 中没有找到 item,此方法也会返回 Collection<T>。This method also returns false if item was not found in the original Collection<T>.
实现
示例
下面的代码示例演示了的多个属性和方法 Collection<T> 。The following code example demonstrates many of the properties and methods of Collection<T>. 此代码示例创建一个字符串集合,使用 Add 方法添加多个字符串,显示 Count ,并列出字符串。The code example creates a collection of strings, uses the Add method to add several strings, displays the Count, and lists the strings. 该示例使用 IndexOf 方法来查找字符串的索引,并使用 Contains 方法来确定字符串是否在集合中。The example uses the IndexOf method to find the index of a string and the Contains method to determine whether a string is in the collection. 该示例使用方法插入字符串 Insert ,并使用 Item[] c # ) 中索引器 (的默认属性检索和设置字符串。The example inserts a string using the Insert method and retrieves and sets strings using the default Item[] property (the indexer in C#). 该示例使用方法和索引按字符串标识删除字符串 Remove RemoveAt 。The example removes strings by string identity using the Remove method and by index using the RemoveAt method. 最后, Clear 使用方法从集合中清除所有字符串。Finally, the Clear method is used to clear all strings from the collection.
using namespace System;
using namespace System::Collections::Generic;
using namespace System::Collections::ObjectModel;
public ref class Demo
{
public:
static void Main()
{
Collection<String^>^ dinosaurs = gcnew Collection<String^>();
dinosaurs->Add("Psitticosaurus");
dinosaurs->Add("Caudipteryx");
dinosaurs->Add("Compsognathus");
dinosaurs->Add("Muttaburrasaurus");
Console::WriteLine("{0} dinosaurs:", dinosaurs->Count);
Display(dinosaurs);
Console::WriteLine("\nIndexOf(\"Muttaburrasaurus\"): {0}",
dinosaurs->IndexOf("Muttaburrasaurus"));
Console::WriteLine("\nContains(\"Caudipteryx\"): {0}",
dinosaurs->Contains("Caudipteryx"));
Console::WriteLine("\nInsert(2, \"Nanotyrannus\")");
dinosaurs->Insert(2, "Nanotyrannus");
Display(dinosaurs);
Console::WriteLine("\ndinosaurs[2]: {0}", dinosaurs[2]);
Console::WriteLine("\ndinosaurs[2] = \"Microraptor\"");
dinosaurs[2] = "Microraptor";
Display(dinosaurs);
Console::WriteLine("\nRemove(\"Microraptor\")");
dinosaurs->Remove("Microraptor");
Display(dinosaurs);
Console::WriteLine("\nRemoveAt(0)");
dinosaurs->RemoveAt(0);
Display(dinosaurs);
Console::WriteLine("\ndinosaurs.Clear()");
dinosaurs->Clear();
Console::WriteLine("Count: {0}", dinosaurs->Count);
}
private:
static void Display(Collection<String^>^ cs)
{
Console::WriteLine();
for each( String^ item in cs )
{
Console::WriteLine(item);
}
}
};
int main()
{
Demo::Main();
}
/* This code example produces the following output:
4 dinosaurs:
Psitticosaurus
Caudipteryx
Compsognathus
Muttaburrasaurus
IndexOf("Muttaburrasaurus"): 3
Contains("Caudipteryx"): True
Insert(2, "Nanotyrannus")
Psitticosaurus
Caudipteryx
Nanotyrannus
Compsognathus
Muttaburrasaurus
dinosaurs[2]: Nanotyrannus
dinosaurs[2] = "Microraptor"
Psitticosaurus
Caudipteryx
Microraptor
Compsognathus
Muttaburrasaurus
Remove("Microraptor")
Psitticosaurus
Caudipteryx
Compsognathus
Muttaburrasaurus
RemoveAt(0)
Caudipteryx
Compsognathus
Muttaburrasaurus
dinosaurs.Clear()
Count: 0
*/
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
public class Demo
{
public static void Main()
{
Collection<string> dinosaurs = new Collection<string>();
dinosaurs.Add("Psitticosaurus");
dinosaurs.Add("Caudipteryx");
dinosaurs.Add("Compsognathus");
dinosaurs.Add("Muttaburrasaurus");
Console.WriteLine("{0} dinosaurs:", dinosaurs.Count);
Display(dinosaurs);
Console.WriteLine("\nIndexOf(\"Muttaburrasaurus\"): {0}",
dinosaurs.IndexOf("Muttaburrasaurus"));
Console.WriteLine("\nContains(\"Caudipteryx\"): {0}",
dinosaurs.Contains("Caudipteryx"));
Console.WriteLine("\nInsert(2, \"Nanotyrannus\")");
dinosaurs.Insert(2, "Nanotyrannus");
Display(dinosaurs);
Console.WriteLine("\ndinosaurs[2]: {0}", dinosaurs[2]);
Console.WriteLine("\ndinosaurs[2] = \"Microraptor\"");
dinosaurs[2] = "Microraptor";
Display(dinosaurs);
Console.WriteLine("\nRemove(\"Microraptor\")");
dinosaurs.Remove("Microraptor");
Display(dinosaurs);
Console.WriteLine("\nRemoveAt(0)");
dinosaurs.RemoveAt(0);
Display(dinosaurs);
Console.WriteLine("\ndinosaurs.Clear()");
dinosaurs.Clear();
Console.WriteLine("Count: {0}", dinosaurs.Count);
}
private static void Display(Collection<string> cs)
{
Console.WriteLine();
foreach( string item in cs )
{
Console.WriteLine(item);
}
}
}
/* This code example produces the following output:
4 dinosaurs:
Psitticosaurus
Caudipteryx
Compsognathus
Muttaburrasaurus
IndexOf("Muttaburrasaurus"): 3
Contains("Caudipteryx"): True
Insert(2, "Nanotyrannus")
Psitticosaurus
Caudipteryx
Nanotyrannus
Compsognathus
Muttaburrasaurus
dinosaurs[2]: Nanotyrannus
dinosaurs[2] = "Microraptor"
Psitticosaurus
Caudipteryx
Microraptor
Compsognathus
Muttaburrasaurus
Remove("Microraptor")
Psitticosaurus
Caudipteryx
Compsognathus
Muttaburrasaurus
RemoveAt(0)
Caudipteryx
Compsognathus
Muttaburrasaurus
dinosaurs.Clear()
Count: 0
*/
Imports System.Collections.Generic
Imports System.Collections.ObjectModel
Public Class Demo
Public Shared Sub Main()
Dim dinosaurs As New Collection(Of String)
dinosaurs.Add("Psitticosaurus")
dinosaurs.Add("Caudipteryx")
dinosaurs.Add("Compsognathus")
dinosaurs.Add("Muttaburrasaurus")
Console.WriteLine("{0} dinosaurs:", dinosaurs.Count)
Display(dinosaurs)
Console.WriteLine(vbLf & "IndexOf(""Muttaburrasaurus""): {0}", _
dinosaurs.IndexOf("Muttaburrasaurus"))
Console.WriteLine(vbLf & "Contains(""Caudipteryx""): {0}", _
dinosaurs.Contains("Caudipteryx"))
Console.WriteLine(vbLf & "Insert(2, ""Nanotyrannus"")")
dinosaurs.Insert(2, "Nanotyrannus")
Display(dinosaurs)
Console.WriteLine(vbLf & "dinosaurs(2): {0}", dinosaurs(2))
Console.WriteLine(vbLf & "dinosaurs(2) = ""Microraptor""")
dinosaurs(2) = "Microraptor"
Display(dinosaurs)
Console.WriteLine(vbLf & "Remove(""Microraptor"")")
dinosaurs.Remove("Microraptor")
Display(dinosaurs)
Console.WriteLine(vbLf & "RemoveAt(0)")
dinosaurs.RemoveAt(0)
Display(dinosaurs)
Console.WriteLine(vbLf & "dinosaurs.Clear()")
dinosaurs.Clear()
Console.WriteLine("Count: {0}", dinosaurs.Count)
End Sub
Private Shared Sub Display(ByVal cs As Collection(Of String))
Console.WriteLine()
For Each item As String In cs
Console.WriteLine(item)
Next item
End Sub
End Class
' This code example produces the following output:
'
'4 dinosaurs:
'
'Psitticosaurus
'Caudipteryx
'Compsognathus
'Muttaburrasaurus
'
'IndexOf("Muttaburrasaurus"): 3
'
'Contains("Caudipteryx"): True
'
'Insert(2, "Nanotyrannus")
'
'Psitticosaurus
'Caudipteryx
'Nanotyrannus
'Compsognathus
'Muttaburrasaurus
'
'dinosaurs(2): Nanotyrannus
'
'dinosaurs(2) = "Microraptor"
'
'Psitticosaurus
'Caudipteryx
'Microraptor
'Compsognathus
'Muttaburrasaurus
'
'Remove("Microraptor")
'
'Psitticosaurus
'Caudipteryx
'Compsognathus
'Muttaburrasaurus
'
'RemoveAt(0)
'
'Caudipteryx
'Compsognathus
'Muttaburrasaurus
'
'dinosaurs.Clear()
'Count: 0
注解
此方法使用的默认相等比较器 EqualityComparer<T>.Default T (列表中的值的类型)确定相等性。This method determines equality using the default equality comparer EqualityComparer<T>.Default for T, the type of values in the list.
此方法执行线性搜索;因此,平均执行时间与成正比 Count 。This method performs a linear search; therefore, the average execution time is proportional to Count. 也就是说,此方法是 O (n) 操作,其中 n 是 Count 。That is, this method is an O(n) operation, where n is Count.
继承者说明
派生类可以重写 RemoveItem(Int32) 来更改此方法的行为。Derived classes can override RemoveItem(Int32) to change the behavior of this method.