ArrayList.LastIndexOf 方法
定義
重要
部分資訊涉及發行前產品,在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊,不做任何明確或隱含的瑕疵擔保。
傳回 ArrayList 或其中一部分中最後一次出現某值之以零為起始的索引。
多載
LastIndexOf(Object) | |
LastIndexOf(Object, Int32) |
在 ArrayList 中從第一個項目開始到指定的索引這個範圍內,搜尋指定的 Object,並傳回最後一次出現的索引值 (以零為起始)。 |
LastIndexOf(Object, Int32, Int32) |
搜尋指定的 Object,並傳回 ArrayList 中包含指定之項目數且結束於指定之索引的項目範圍內,最後一個相符項目之以零為起始的索引。 |
LastIndexOf(Object)
- 來源:
- ArrayList.cs
- 來源:
- ArrayList.cs
- 來源:
- ArrayList.cs
public:
virtual int LastIndexOf(System::Object ^ value);
public virtual int LastIndexOf (object value);
public virtual int LastIndexOf (object? value);
abstract member LastIndexOf : obj -> int
override this.LastIndexOf : obj -> int
Public Overridable Function LastIndexOf (value As Object) As Integer
參數
傳回
如果找到的話,則為整個 ArrayList 中最後一次出現 value
之以零為起始的索引 (如有找到),如未找到則為 -1。
範例
下列程式代碼範例示範如何判斷指定項目最後一次出現的索引。
using namespace System;
using namespace System::Collections;
void PrintIndexAndValues( IEnumerable^ myList );
int main()
{
// Creates and initializes a new ArrayList with three elements of the same value.
ArrayList^ myAL = gcnew ArrayList;
myAL->Add( "the" );
myAL->Add( "quick" );
myAL->Add( "brown" );
myAL->Add( "fox" );
myAL->Add( "jumps" );
myAL->Add( "over" );
myAL->Add( "the" );
myAL->Add( "lazy" );
myAL->Add( "dog" );
myAL->Add( "in" );
myAL->Add( "the" );
myAL->Add( "barn" );
// Displays the values of the ArrayList.
Console::WriteLine( "The ArrayList contains the following values:" );
PrintIndexAndValues( myAL );
// Searches for the last occurrence of the duplicated value.
String^ myString = "the";
int myIndex = myAL->LastIndexOf( myString );
Console::WriteLine( "The last occurrence of \"{0}\" is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in the first section of the ArrayList.
myIndex = myAL->LastIndexOf( myString, 8 );
Console::WriteLine( "The last occurrence of \"{0}\" between the start and index 8 is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward.
myIndex = myAL->LastIndexOf( myString, 10, 6 );
Console::WriteLine( "The last occurrence of \"{0}\" between index 10 and index 5 is at index {1}.", myString, myIndex );
}
void PrintIndexAndValues( IEnumerable^ myList )
{
int i = 0;
IEnumerator^ myEnum = myList->GetEnumerator();
while ( myEnum->MoveNext() )
{
Object^ obj = safe_cast<Object^>(myEnum->Current);
Console::WriteLine( " [{0}]: {1}", i++, obj );
}
Console::WriteLine();
}
/*
This code produces the following output.
The ArrayList contains the following values:
[0]: the
[1]: quick
[2]: brown
[3]: fox
[4]: jumps
[5]: over
[6]: the
[7]: lazy
[8]: dog
[9]: in
[10]: the
[11]: barn
The last occurrence of "the" is at index 10.
The last occurrence of "the" between the start and index 8 is at index 6.
The last occurrence of "the" between index 10 and index 5 is at index 10.
*/
using System;
using System.Collections;
public class SamplesArrayList {
public static void Main() {
// Creates and initializes a new ArrayList with three elements of the same value.
ArrayList myAL = new ArrayList();
myAL.Add( "the" );
myAL.Add( "quick" );
myAL.Add( "brown" );
myAL.Add( "fox" );
myAL.Add( "jumps" );
myAL.Add( "over" );
myAL.Add( "the" );
myAL.Add( "lazy" );
myAL.Add( "dog" );
myAL.Add( "in" );
myAL.Add( "the" );
myAL.Add( "barn" );
// Displays the values of the ArrayList.
Console.WriteLine( "The ArrayList contains the following values:" );
PrintIndexAndValues( myAL );
// Searches for the last occurrence of the duplicated value.
string myString = "the";
int myIndex = myAL.LastIndexOf( myString );
Console.WriteLine( "The last occurrence of \"{0}\" is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in the first section of the ArrayList.
myIndex = myAL.LastIndexOf( myString, 8 );
Console.WriteLine( "The last occurrence of \"{0}\" between the start and index 8 is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward.
myIndex = myAL.LastIndexOf( myString, 10, 6 );
Console.WriteLine( "The last occurrence of \"{0}\" between index 10 and index 5 is at index {1}.", myString, myIndex );
}
public static void PrintIndexAndValues( IEnumerable myList ) {
int i = 0;
foreach ( Object obj in myList )
Console.WriteLine( " [{0}]: {1}", i++, obj );
Console.WriteLine();
}
}
/*
This code produces the following output.
The ArrayList contains the following values:
[0]: the
[1]: quick
[2]: brown
[3]: fox
[4]: jumps
[5]: over
[6]: the
[7]: lazy
[8]: dog
[9]: in
[10]: the
[11]: barn
The last occurrence of "the" is at index 10.
The last occurrence of "the" between the start and index 8 is at index 6.
The last occurrence of "the" between index 10 and index 5 is at index 10.
*/
Imports System.Collections
Public Class SamplesArrayList
Public Shared Sub Main()
' Creates and initializes a new ArrayList with three elements of the same value.
Dim myAL As New ArrayList()
myAL.Add("the")
myAL.Add("quick")
myAL.Add("brown")
myAL.Add("fox")
myAL.Add("jumps")
myAL.Add("over")
myAL.Add("the")
myAL.Add("lazy")
myAL.Add("dog")
myAL.Add("in")
myAL.Add("the")
myAL.Add("barn")
' Displays the values of the ArrayList.
Console.WriteLine("The ArrayList contains the following values:")
PrintIndexAndValues(myAL)
' Searches for the last occurrence of the duplicated value.
Dim myString As [String] = "the"
Dim myIndex As Integer = myAL.LastIndexOf(myString)
Console.WriteLine("The last occurrence of ""{0}"" is at index {1}.", myString, myIndex)
' Searches for the last occurrence of the duplicated value in the first section of the ArrayList.
myIndex = myAL.LastIndexOf(myString, 8)
Console.WriteLine("The last occurrence of ""{0}"" between the start and index 8 is at index {1}.", myString, myIndex)
' Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward.
myIndex = myAL.LastIndexOf(myString, 10, 6)
Console.WriteLine("The last occurrence of ""{0}"" between index 10 and index 5 is at index {1}.", myString, myIndex)
End Sub
Public Shared Sub PrintIndexAndValues(myList As IEnumerable)
Dim i as Integer
Dim obj As [Object]
For Each obj In myList
Console.WriteLine(" [{0}]: {1}", i, obj)
i = i + 1
Next obj
Console.WriteLine()
End Sub
End Class
' This code produces the following output.
'
' The ArrayList contains the following values:
' [0]: the
' [1]: quick
' [2]: brown
' [3]: fox
' [4]: jumps
' [5]: over
' [6]: the
' [7]: lazy
' [8]: dog
' [9]: in
' [10]: the
' [11]: barn
'
' The last occurrence of "the" is at index 10.
' The last occurrence of "the" between the start and index 8 is at index 6.
' The last occurrence of "the" between index 10 and index 5 is at index 10.
備註
ArrayList會從最後一個專案往後搜尋 ,並結束於第一個專案。
此方法會執行線性搜尋;因此,這個方法是 O(n)
作業,其中 n
是 Count。
從 .NET Framework 2.0 開始,這個方法會使用 集合的物件 Equals 和 CompareTo 方法item
來判斷專案是否存在。 在舊版的 .NET Framework 中,這個判斷方式是在Equals集合中的 物件上使用 參數的 item
和 CompareTo 方法進行。
另請參閱
適用於
LastIndexOf(Object, Int32)
- 來源:
- ArrayList.cs
- 來源:
- ArrayList.cs
- 來源:
- ArrayList.cs
public:
virtual int LastIndexOf(System::Object ^ value, int startIndex);
public virtual int LastIndexOf (object value, int startIndex);
public virtual int LastIndexOf (object? value, int startIndex);
abstract member LastIndexOf : obj * int -> int
override this.LastIndexOf : obj * int -> int
Public Overridable Function LastIndexOf (value As Object, startIndex As Integer) As Integer
參數
- startIndex
- Int32
向後搜尋之以零為起始的起始索引。
傳回
在 ArrayList 中從第一個元素開始到 startIndex
這段範圍內,如果有找到指定的 value
最後一次出現的位置,則為該位置以零為起始的索引,如未找到則為 -1。
例外狀況
startIndex
超出 ArrayList 的有效索引範圍。
範例
下列程式代碼範例示範如何判斷指定項目最後一次出現的索引。
using namespace System;
using namespace System::Collections;
void PrintIndexAndValues( IEnumerable^ myList );
int main()
{
// Creates and initializes a new ArrayList with three elements of the same value.
ArrayList^ myAL = gcnew ArrayList;
myAL->Add( "the" );
myAL->Add( "quick" );
myAL->Add( "brown" );
myAL->Add( "fox" );
myAL->Add( "jumps" );
myAL->Add( "over" );
myAL->Add( "the" );
myAL->Add( "lazy" );
myAL->Add( "dog" );
myAL->Add( "in" );
myAL->Add( "the" );
myAL->Add( "barn" );
// Displays the values of the ArrayList.
Console::WriteLine( "The ArrayList contains the following values:" );
PrintIndexAndValues( myAL );
// Searches for the last occurrence of the duplicated value.
String^ myString = "the";
int myIndex = myAL->LastIndexOf( myString );
Console::WriteLine( "The last occurrence of \"{0}\" is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in the first section of the ArrayList.
myIndex = myAL->LastIndexOf( myString, 8 );
Console::WriteLine( "The last occurrence of \"{0}\" between the start and index 8 is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward.
myIndex = myAL->LastIndexOf( myString, 10, 6 );
Console::WriteLine( "The last occurrence of \"{0}\" between index 10 and index 5 is at index {1}.", myString, myIndex );
}
void PrintIndexAndValues( IEnumerable^ myList )
{
int i = 0;
IEnumerator^ myEnum = myList->GetEnumerator();
while ( myEnum->MoveNext() )
{
Object^ obj = safe_cast<Object^>(myEnum->Current);
Console::WriteLine( " [{0}]: {1}", i++, obj );
}
Console::WriteLine();
}
/*
This code produces the following output.
The ArrayList contains the following values:
[0]: the
[1]: quick
[2]: brown
[3]: fox
[4]: jumps
[5]: over
[6]: the
[7]: lazy
[8]: dog
[9]: in
[10]: the
[11]: barn
The last occurrence of "the" is at index 10.
The last occurrence of "the" between the start and index 8 is at index 6.
The last occurrence of "the" between index 10 and index 5 is at index 10.
*/
using System;
using System.Collections;
public class SamplesArrayList {
public static void Main() {
// Creates and initializes a new ArrayList with three elements of the same value.
ArrayList myAL = new ArrayList();
myAL.Add( "the" );
myAL.Add( "quick" );
myAL.Add( "brown" );
myAL.Add( "fox" );
myAL.Add( "jumps" );
myAL.Add( "over" );
myAL.Add( "the" );
myAL.Add( "lazy" );
myAL.Add( "dog" );
myAL.Add( "in" );
myAL.Add( "the" );
myAL.Add( "barn" );
// Displays the values of the ArrayList.
Console.WriteLine( "The ArrayList contains the following values:" );
PrintIndexAndValues( myAL );
// Searches for the last occurrence of the duplicated value.
string myString = "the";
int myIndex = myAL.LastIndexOf( myString );
Console.WriteLine( "The last occurrence of \"{0}\" is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in the first section of the ArrayList.
myIndex = myAL.LastIndexOf( myString, 8 );
Console.WriteLine( "The last occurrence of \"{0}\" between the start and index 8 is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward.
myIndex = myAL.LastIndexOf( myString, 10, 6 );
Console.WriteLine( "The last occurrence of \"{0}\" between index 10 and index 5 is at index {1}.", myString, myIndex );
}
public static void PrintIndexAndValues( IEnumerable myList ) {
int i = 0;
foreach ( Object obj in myList )
Console.WriteLine( " [{0}]: {1}", i++, obj );
Console.WriteLine();
}
}
/*
This code produces the following output.
The ArrayList contains the following values:
[0]: the
[1]: quick
[2]: brown
[3]: fox
[4]: jumps
[5]: over
[6]: the
[7]: lazy
[8]: dog
[9]: in
[10]: the
[11]: barn
The last occurrence of "the" is at index 10.
The last occurrence of "the" between the start and index 8 is at index 6.
The last occurrence of "the" between index 10 and index 5 is at index 10.
*/
Imports System.Collections
Public Class SamplesArrayList
Public Shared Sub Main()
' Creates and initializes a new ArrayList with three elements of the same value.
Dim myAL As New ArrayList()
myAL.Add("the")
myAL.Add("quick")
myAL.Add("brown")
myAL.Add("fox")
myAL.Add("jumps")
myAL.Add("over")
myAL.Add("the")
myAL.Add("lazy")
myAL.Add("dog")
myAL.Add("in")
myAL.Add("the")
myAL.Add("barn")
' Displays the values of the ArrayList.
Console.WriteLine("The ArrayList contains the following values:")
PrintIndexAndValues(myAL)
' Searches for the last occurrence of the duplicated value.
Dim myString As [String] = "the"
Dim myIndex As Integer = myAL.LastIndexOf(myString)
Console.WriteLine("The last occurrence of ""{0}"" is at index {1}.", myString, myIndex)
' Searches for the last occurrence of the duplicated value in the first section of the ArrayList.
myIndex = myAL.LastIndexOf(myString, 8)
Console.WriteLine("The last occurrence of ""{0}"" between the start and index 8 is at index {1}.", myString, myIndex)
' Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward.
myIndex = myAL.LastIndexOf(myString, 10, 6)
Console.WriteLine("The last occurrence of ""{0}"" between index 10 and index 5 is at index {1}.", myString, myIndex)
End Sub
Public Shared Sub PrintIndexAndValues(myList As IEnumerable)
Dim i as Integer
Dim obj As [Object]
For Each obj In myList
Console.WriteLine(" [{0}]: {1}", i, obj)
i = i + 1
Next obj
Console.WriteLine()
End Sub
End Class
' This code produces the following output.
'
' The ArrayList contains the following values:
' [0]: the
' [1]: quick
' [2]: brown
' [3]: fox
' [4]: jumps
' [5]: over
' [6]: the
' [7]: lazy
' [8]: dog
' [9]: in
' [10]: the
' [11]: barn
'
' The last occurrence of "the" is at index 10.
' The last occurrence of "the" between the start and index 8 is at index 6.
' The last occurrence of "the" between index 10 and index 5 is at index 10.
備註
從 ArrayList 開始 startIndex
往後搜尋 ,並在第一個元素結束。
此方法會執行線性搜尋;因此,這個方法是 O(n)
作業,其中 n
是 從 開頭 ArrayList 到 startIndex
的項目數目。
這個方法會呼叫 Object.Equals來判斷相等。
從 .NET Framework 2.0 開始,這個方法會使用 集合的物件 Equals 和 CompareTo 方法item
來判斷專案是否存在。 在舊版的 .NET Framework 中,這個判斷方式是在Equals集合中的 物件上使用 參數的 item
和 CompareTo 方法進行。
另請參閱
適用於
LastIndexOf(Object, Int32, Int32)
- 來源:
- ArrayList.cs
- 來源:
- ArrayList.cs
- 來源:
- ArrayList.cs
public:
virtual int LastIndexOf(System::Object ^ value, int startIndex, int count);
public virtual int LastIndexOf (object value, int startIndex, int count);
public virtual int LastIndexOf (object? value, int startIndex, int count);
abstract member LastIndexOf : obj * int * int -> int
override this.LastIndexOf : obj * int * int -> int
Public Overridable Function LastIndexOf (value As Object, startIndex As Integer, count As Integer) As Integer
參數
- startIndex
- Int32
向後搜尋之以零為起始的起始索引。
- count
- Int32
區段中要搜尋的項目數目。
傳回
如果找到,則為 ArrayList 中包含 count
個元素且結束於 startIndex
的元素範圍內,value
的最後一個相符項目之以零為起始的索引,否則為 -1。
例外狀況
範例
下列程式代碼範例示範如何判斷指定項目最後一次出現的索引。 請注意, LastIndexOf
是回溯搜尋;因此, count
必須小於或等於 startIndex
+ 1。
using namespace System;
using namespace System::Collections;
void PrintIndexAndValues( IEnumerable^ myList );
int main()
{
// Creates and initializes a new ArrayList with three elements of the same value.
ArrayList^ myAL = gcnew ArrayList;
myAL->Add( "the" );
myAL->Add( "quick" );
myAL->Add( "brown" );
myAL->Add( "fox" );
myAL->Add( "jumps" );
myAL->Add( "over" );
myAL->Add( "the" );
myAL->Add( "lazy" );
myAL->Add( "dog" );
myAL->Add( "in" );
myAL->Add( "the" );
myAL->Add( "barn" );
// Displays the values of the ArrayList.
Console::WriteLine( "The ArrayList contains the following values:" );
PrintIndexAndValues( myAL );
// Searches for the last occurrence of the duplicated value.
String^ myString = "the";
int myIndex = myAL->LastIndexOf( myString );
Console::WriteLine( "The last occurrence of \"{0}\" is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in the first section of the ArrayList.
myIndex = myAL->LastIndexOf( myString, 8 );
Console::WriteLine( "The last occurrence of \"{0}\" between the start and index 8 is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward.
myIndex = myAL->LastIndexOf( myString, 10, 6 );
Console::WriteLine( "The last occurrence of \"{0}\" between index 10 and index 5 is at index {1}.", myString, myIndex );
}
void PrintIndexAndValues( IEnumerable^ myList )
{
int i = 0;
IEnumerator^ myEnum = myList->GetEnumerator();
while ( myEnum->MoveNext() )
{
Object^ obj = safe_cast<Object^>(myEnum->Current);
Console::WriteLine( " [{0}]: {1}", i++, obj );
}
Console::WriteLine();
}
/*
This code produces the following output.
The ArrayList contains the following values:
[0]: the
[1]: quick
[2]: brown
[3]: fox
[4]: jumps
[5]: over
[6]: the
[7]: lazy
[8]: dog
[9]: in
[10]: the
[11]: barn
The last occurrence of "the" is at index 10.
The last occurrence of "the" between the start and index 8 is at index 6.
The last occurrence of "the" between index 10 and index 5 is at index 10.
*/
using System;
using System.Collections;
public class SamplesArrayList {
public static void Main() {
// Creates and initializes a new ArrayList with three elements of the same value.
ArrayList myAL = new ArrayList();
myAL.Add( "the" );
myAL.Add( "quick" );
myAL.Add( "brown" );
myAL.Add( "fox" );
myAL.Add( "jumps" );
myAL.Add( "over" );
myAL.Add( "the" );
myAL.Add( "lazy" );
myAL.Add( "dog" );
myAL.Add( "in" );
myAL.Add( "the" );
myAL.Add( "barn" );
// Displays the values of the ArrayList.
Console.WriteLine( "The ArrayList contains the following values:" );
PrintIndexAndValues( myAL );
// Searches for the last occurrence of the duplicated value.
string myString = "the";
int myIndex = myAL.LastIndexOf( myString );
Console.WriteLine( "The last occurrence of \"{0}\" is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in the first section of the ArrayList.
myIndex = myAL.LastIndexOf( myString, 8 );
Console.WriteLine( "The last occurrence of \"{0}\" between the start and index 8 is at index {1}.", myString, myIndex );
// Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward.
myIndex = myAL.LastIndexOf( myString, 10, 6 );
Console.WriteLine( "The last occurrence of \"{0}\" between index 10 and index 5 is at index {1}.", myString, myIndex );
}
public static void PrintIndexAndValues( IEnumerable myList ) {
int i = 0;
foreach ( Object obj in myList )
Console.WriteLine( " [{0}]: {1}", i++, obj );
Console.WriteLine();
}
}
/*
This code produces the following output.
The ArrayList contains the following values:
[0]: the
[1]: quick
[2]: brown
[3]: fox
[4]: jumps
[5]: over
[6]: the
[7]: lazy
[8]: dog
[9]: in
[10]: the
[11]: barn
The last occurrence of "the" is at index 10.
The last occurrence of "the" between the start and index 8 is at index 6.
The last occurrence of "the" between index 10 and index 5 is at index 10.
*/
Imports System.Collections
Public Class SamplesArrayList
Public Shared Sub Main()
' Creates and initializes a new ArrayList with three elements of the same value.
Dim myAL As New ArrayList()
myAL.Add("the")
myAL.Add("quick")
myAL.Add("brown")
myAL.Add("fox")
myAL.Add("jumps")
myAL.Add("over")
myAL.Add("the")
myAL.Add("lazy")
myAL.Add("dog")
myAL.Add("in")
myAL.Add("the")
myAL.Add("barn")
' Displays the values of the ArrayList.
Console.WriteLine("The ArrayList contains the following values:")
PrintIndexAndValues(myAL)
' Searches for the last occurrence of the duplicated value.
Dim myString As [String] = "the"
Dim myIndex As Integer = myAL.LastIndexOf(myString)
Console.WriteLine("The last occurrence of ""{0}"" is at index {1}.", myString, myIndex)
' Searches for the last occurrence of the duplicated value in the first section of the ArrayList.
myIndex = myAL.LastIndexOf(myString, 8)
Console.WriteLine("The last occurrence of ""{0}"" between the start and index 8 is at index {1}.", myString, myIndex)
' Searches for the last occurrence of the duplicated value in a section of the ArrayList. Note that the start index is greater than the end index because the search is done backward.
myIndex = myAL.LastIndexOf(myString, 10, 6)
Console.WriteLine("The last occurrence of ""{0}"" between index 10 and index 5 is at index {1}.", myString, myIndex)
End Sub
Public Shared Sub PrintIndexAndValues(myList As IEnumerable)
Dim i as Integer
Dim obj As [Object]
For Each obj In myList
Console.WriteLine(" [{0}]: {1}", i, obj)
i = i + 1
Next obj
Console.WriteLine()
End Sub
End Class
' This code produces the following output.
'
' The ArrayList contains the following values:
' [0]: the
' [1]: quick
' [2]: brown
' [3]: fox
' [4]: jumps
' [5]: over
' [6]: the
' [7]: lazy
' [8]: dog
' [9]: in
' [10]: the
' [11]: barn
'
' The last occurrence of "the" is at index 10.
' The last occurrence of "the" between the start and index 8 is at index 6.
' The last occurrence of "the" between index 10 and index 5 is at index 10.
備註
如果 大於 0,則會 ArrayList 從 後 startIndex
向搜尋 ,並結束於 startIndex
減號加上 count
count
1。
此方法會執行線性搜尋;因此,這個方法是 O(n)
作業,其中 n
是 count
。
這個方法會呼叫 Object.Equals來判斷相等。
從 .NET Framework 2.0 開始,這個方法會使用 集合的物件 Equals 和 CompareTo 方法item
來判斷專案是否存在。 在舊版的 .NET Framework 中,這個判斷方式是在Equals集合中的 物件上使用 參數的 item
和 CompareTo 方法進行。