CollectionBase.OnValidate 方法
当验证值时执行其他自定义进程。
**命名空间:**System.Collections
**程序集:**mscorlib（在 mscorlib.dll 中）
语法
声明
Protected Overridable Sub OnValidate ( _
value As Object _
)
用法
Dim value As Object
Me.OnValidate(value)
protected virtual void OnValidate (
Object value
)
protected:
virtual void OnValidate (
Object^ value
)
protected void OnValidate (
Object value
)
protected function OnValidate (
value : Object
)
参数
- value
要验证的对象。
备注
此方法的默认实现确定 value 是否为 空引用（在 Visual Basic 中为 Nothing），如果是，则引发 ArgumentNullException。这是为了由派生类重写，以便在验证指定元素时执行其他操作。
仅对 List 属性所返回的实例调用 On* 方法，而不对 InnerList 属性所返回的实例调用这些方法。
此方法的默认实现的运算复杂度为 O(1)。
给实现者的说明 此方法允许实施者定义当执行基础 System.Collections.ArrayList 的标准行为时必须执行的进程。通过定义此方法，实施者可以向继承方法添加功能，而无须重写所有其他方法。 OnValidate 可用于对集合中可接受的对象的类型进行限制。默认实现将防止在基础 System.Collections.ArrayList 中添加或移除 空引用（在 Visual Basic 中为 Nothing）。 OnValidate 在调用 OnInsert、OnRemove 和 OnSet 之前调用。
示例
下面的代码示例实现 CollectionBase 类，并使用该实现创建 Int16 对象的集合。
Imports System
Imports System.Collections
Public Class Int16Collection
Inherits CollectionBase
Default Public Property Item(index As Integer) As Int16
Get
Return CType(List(index), Int16)
End Get
Set
List(index) = value
End Set
End Property
Public Function Add(value As Int16) As Integer
Return List.Add(value)
End Function 'Add
Public Function IndexOf(value As Int16) As Integer
Return List.IndexOf(value)
End Function 'IndexOf
Public Sub Insert(index As Integer, value As Int16)
List.Insert(index, value)
End Sub 'Insert
Public Sub Remove(value As Int16)
List.Remove(value)
End Sub 'Remove
Public Function Contains(value As Int16) As Boolean
' If value is not of type Int16, this will return false.
Return List.Contains(value)
End Function 'Contains
Protected Overrides Sub OnInsert(index As Integer, value As Object)
' Insert additional code to be run only when inserting values.
End Sub 'OnInsert
Protected Overrides Sub OnRemove(index As Integer, value As Object)
' Insert additional code to be run only when removing values.
End Sub 'OnRemove
Protected Overrides Sub OnSet(index As Integer, oldValue As Object, newValue As Object)
' Insert additional code to be run only when setting values.
End Sub 'OnSet
Protected Overrides Sub OnValidate(value As Object)
If Not GetType(System.Int16).IsAssignableFrom(value.GetType()) Then
Throw New ArgumentException("value must be of type Int16.", "value")
End If
End Sub 'OnValidate
End Class 'Int16Collection
Public Class SamplesCollectionBase
Public Shared Sub Main()
' Creates and initializes a new CollectionBase.
Dim myI16 As New Int16Collection()
' Adds elements to the collection.
myI16.Add( 1 )
myI16.Add( 2 )
myI16.Add( 3 )
myI16.Add( 5 )
myI16.Add( 7 )
' Display the contents of the collection using For Each. This is the preferred method.
Console.WriteLine("Contents of the collection (using For Each):")
PrintValues1(myI16)
' Display the contents of the collection using the enumerator.
Console.WriteLine("Contents of the collection (using enumerator):")
PrintValues2(myI16)
' Display the contents of the collection using the Count property and the Item property.
Console.WriteLine("Initial contents of the collection (using Count and Item):")
PrintIndexAndValues(myI16)
' Searches the collection with Contains and IndexOf.
Console.WriteLine("Contains 3: {0}", myI16.Contains(3))
Console.WriteLine("2 is at index {0}.", myI16.IndexOf(2))
Console.WriteLine()
' Inserts an element into the collection at index 3.
myI16.Insert(3, 13)
Console.WriteLine("Contents of the collection after inserting at index 3:")
PrintIndexAndValues(myI16)
' Gets and sets an element using the index.
myI16(4) = 123
Console.WriteLine("Contents of the collection after setting the element at index 4 to 123:")
PrintIndexAndValues(myI16)
' Removes an element from the collection.
myI16.Remove(2)
' Display the contents of the collection using the Count property and the Item property.
Console.WriteLine("Contents of the collection after removing the element 2:")
PrintIndexAndValues(myI16)
End Sub 'Main
' Uses the Count property and the Item property.
Public Shared Sub PrintIndexAndValues(myCol As Int16Collection)
Dim i As Integer
For i = 0 To myCol.Count - 1
Console.WriteLine(" [{0}]: {1}", i, myCol(i))
Next i
Console.WriteLine()
End Sub 'PrintIndexAndValues
' Uses the For Each statement which hides the complexity of the enumerator.
' NOTE: The For Each statement is the preferred way of enumerating the contents of a collection.
Public Shared Sub PrintValues1(myCol As Int16Collection)
Dim i16 As Int16
For Each i16 In myCol
Console.WriteLine(" {0}", i16)
Next i16
Console.WriteLine()
End Sub 'PrintValues1
' Uses the enumerator.
' NOTE: The For Each statement is the preferred way of enumerating the contents of a collection.
Public Shared Sub PrintValues2(myCol As Int16Collection)
Dim myEnumerator As System.Collections.IEnumerator = myCol.GetEnumerator()
While myEnumerator.MoveNext()
Console.WriteLine(" {0}", myEnumerator.Current)
End While
Console.WriteLine()
End Sub 'PrintValues2
End Class 'SamplesCollectionBase
'This code produces the following output.
'
'Contents of the collection (using For Each):
' 1
' 2
' 3
' 5
' 7
'
'Contents of the collection (using enumerator):
' 1
' 2
' 3
' 5
' 7
'
'Initial contents of the collection (using Count and Item):
' [0]: 1
' [1]: 2
' [2]: 3
' [3]: 5
' [4]: 7
'
'Contains 3: True
'2 is at index 1.
'
'Contents of the collection after inserting at index 3:
' [0]: 1
' [1]: 2
' [2]: 3
' [3]: 13
' [4]: 5
' [5]: 7
'
'Contents of the collection after setting the element at index 4 to 123:
' [0]: 1
' [1]: 2
' [2]: 3
' [3]: 13
' [4]: 123
' [5]: 7
'
'Contents of the collection after removing the element 2:
' [0]: 1
' [1]: 3
' [2]: 13
' [3]: 123
' [4]: 7
using System;
using System.Collections;
public class Int16Collection : CollectionBase {
public Int16 this[ int index ] {
get {
return( (Int16) List[index] );
}
set {
List[index] = value;
}
}
public int Add( Int16 value ) {
return( List.Add( value ) );
}
public int IndexOf( Int16 value ) {
return( List.IndexOf( value ) );
}
public void Insert( int index, Int16 value ) {
List.Insert( index, value );
}
public void Remove( Int16 value ) {
List.Remove( value );
}
public bool Contains( Int16 value ) {
// If value is not of type Int16, this will return false.
return( List.Contains( value ) );
}
protected override void OnInsert( int index, Object value ) {
// Insert additional code to be run only when inserting values.
}
protected override void OnRemove( int index, Object value ) {
// Insert additional code to be run only when removing values.
}
protected override void OnSet( int index, Object oldValue, Object newValue ) {
// Insert additional code to be run only when setting values.
}
protected override void OnValidate( Object value ) {
if ( value.GetType() != typeof(System.Int16) )
throw new ArgumentException( "value must be of type Int16.", "value" );
}
}
public class SamplesCollectionBase {
public static void Main() {
// Create and initialize a new CollectionBase.
Int16Collection myI16 = new Int16Collection();
// Add elements to the collection.
myI16.Add( (Int16) 1 );
myI16.Add( (Int16) 2 );
myI16.Add( (Int16) 3 );
myI16.Add( (Int16) 5 );
myI16.Add( (Int16) 7 );
// Display the contents of the collection using foreach. This is the preferred method.
Console.WriteLine( "Contents of the collection (using foreach):" );
PrintValues1( myI16 );
// Display the contents of the collection using the enumerator.
Console.WriteLine( "Contents of the collection (using enumerator):" );
PrintValues2( myI16 );
// Display the contents of the collection using the Count property and the Item property.
Console.WriteLine( "Initial contents of the collection (using Count and Item):" );
PrintIndexAndValues( myI16 );
// Search the collection with Contains and IndexOf.
Console.WriteLine( "Contains 3: {0}", myI16.Contains( 3 ) );
Console.WriteLine( "2 is at index {0}.", myI16.IndexOf( 2 ) );
Console.WriteLine();
// Insert an element into the collection at index 3.
myI16.Insert( 3, (Int16) 13 );
Console.WriteLine( "Contents of the collection after inserting at index 3:" );
PrintIndexAndValues( myI16 );
// Get and set an element using the index.
myI16[4] = 123;
Console.WriteLine( "Contents of the collection after setting the element at index 4 to 123:" );
PrintIndexAndValues( myI16 );
// Remove an element from the collection.
myI16.Remove( (Int16) 2 );
// Display the contents of the collection using the Count property and the Item property.
Console.WriteLine( "Contents of the collection after removing the element 2:" );
PrintIndexAndValues( myI16 );
}
// Uses the Count property and the Item property.
public static void PrintIndexAndValues( Int16Collection myCol ) {
for ( int i = 0; i < myCol.Count; i++ )
Console.WriteLine( " [{0}]: {1}", i, myCol[i] );
Console.WriteLine();
}
// Uses the foreach statement which hides the complexity of the enumerator.
// NOTE: The foreach statement is the preferred way of enumerating the contents of a collection.
public static void PrintValues1( Int16Collection myCol ) {
foreach ( Int16 i16 in myCol )
Console.WriteLine( " {0}", i16 );
Console.WriteLine();
}
// Uses the enumerator.
// NOTE: The foreach statement is the preferred way of enumerating the contents of a collection.
public static void PrintValues2( Int16Collection myCol ) {
System.Collections.IEnumerator myEnumerator = myCol.GetEnumerator();
while ( myEnumerator.MoveNext() )
Console.WriteLine( " {0}", myEnumerator.Current );
Console.WriteLine();
}
}
/*
This code produces the following output.
Contents of the collection (using foreach):
1
2
3
5
7
Contents of the collection (using enumerator):
1
2
3
5
7
Initial contents of the collection (using Count and Item):
[0]: 1
[1]: 2
[2]: 3
[3]: 5
[4]: 7
Contains 3: True
2 is at index 1.
Contents of the collection after inserting at index 3:
[0]: 1
[1]: 2
[2]: 3
[3]: 13
[4]: 5
[5]: 7
Contents of the collection after setting the element at index 4 to 123:
[0]: 1
[1]: 2
[2]: 3
[3]: 13
[4]: 123
[5]: 7
Contents of the collection after removing the element 2:
[0]: 1
[1]: 3
[2]: 13
[3]: 123
[4]: 7
*/
#using <System.dll>
using namespace System;
using namespace System::Collections;
public ref class Int16Collection: public CollectionBase
{
public:
property Int16 Item [int]
{
Int16 get( int index )
{
return ( (Int16)(List[ index ]));
}
void set( int index, Int16 value )
{
List[ index ] = value;
}
}
int Add( Int16 value )
{
return (List->Add( value ));
}
int IndexOf( Int16 value )
{
return (List->IndexOf( value ));
}
void Insert( int index, Int16 value )
{
List->Insert( index, value );
}
void Remove( Int16 value )
{
List->Remove( value );
}
bool Contains( Int16 value )
{
// If value is not of type Int16, this will return false.
return (List->Contains( value ));
}
protected:
virtual void OnInsert( int /*index*/, Object^ /*value*/ ) override
{
// Insert additional code to be run only when inserting values.
}
virtual void OnRemove( int /*index*/, Object^ /*value*/ ) override
{
// Insert additional code to be run only when removing values.
}
virtual void OnSet( int /*index*/, Object^ /*oldValue*/, Object^ /*newValue*/ ) override
{
// Insert additional code to be run only when setting values.
}
virtual void OnValidate( Object^ value ) override
{
if ( value->GetType() != Type::GetType( "System.Int16" ) )
throw gcnew ArgumentException( "value must be of type Int16.","value" );
}
};
void PrintIndexAndValues( Int16Collection^ myCol );
void PrintValues2( Int16Collection^ myCol );
int main()
{
// Create and initialize a new CollectionBase.
Int16Collection^ myI16 = gcnew Int16Collection;
// Add elements to the collection.
myI16->Add( (Int16)1 );
myI16->Add( (Int16)2 );
myI16->Add( (Int16)3 );
myI16->Add( (Int16)5 );
myI16->Add( (Int16)7 );
// Display the contents of the collection using the enumerator.
Console::WriteLine( "Contents of the collection (using enumerator):" );
PrintValues2( myI16 );
// Display the contents of the collection using the Count property and the Item property.
Console::WriteLine( "Initial contents of the collection (using Count and Item):" );
PrintIndexAndValues( myI16 );
// Search the collection with Contains and IndexOf.
Console::WriteLine( "Contains 3: {0}", myI16->Contains( 3 ) );
Console::WriteLine( "2 is at index {0}.", myI16->IndexOf( 2 ) );
Console::WriteLine();
// Insert an element into the collection at index 3.
myI16->Insert( 3, (Int16)13 );
Console::WriteLine( "Contents of the collection after inserting at index 3:" );
PrintIndexAndValues( myI16 );
// Get and set an element using the index.
myI16->Item[ 4 ] = 123;
Console::WriteLine( "Contents of the collection after setting the element at index 4 to 123:" );
PrintIndexAndValues( myI16 );
// Remove an element from the collection.
myI16->Remove( (Int16)2 );
// Display the contents of the collection using the Count property and the Item property.
Console::WriteLine( "Contents of the collection after removing the element 2:" );
PrintIndexAndValues( myI16 );
}
// Uses the Count property and the Item property.
void PrintIndexAndValues( Int16Collection^ myCol )
{
for ( int i = 0; i < myCol->Count; i++ )
Console::WriteLine( " [{0}]: {1}", i, myCol->Item[ i ] );
Console::WriteLine();
}
// Uses the enumerator.
void PrintValues2( Int16Collection^ myCol )
{
System::Collections::IEnumerator^ myEnumerator = myCol->GetEnumerator();
while ( myEnumerator->MoveNext() )
Console::WriteLine( " {0}", myEnumerator->Current );
Console::WriteLine();
}
/*
This code produces the following output.
Contents of the collection (using enumerator):
1
2
3
5
7
Initial contents of the collection (using Count and Item):
[0]: 1
[1]: 2
[2]: 3
[3]: 5
[4]: 7
Contains 3: True
2 is at index 1.
Contents of the collection after inserting at index 3:
[0]: 1
[1]: 2
[2]: 3
[3]: 13
[4]: 5
[5]: 7
Contents of the collection after setting the element at index 4 to 123:
[0]: 1
[1]: 2
[2]: 3
[3]: 13
[4]: 123
[5]: 7
Contents of the collection after removing the element 2:
[0]: 1
[1]: 3
[2]: 13
[3]: 123
[4]: 7
*/
import System.* ;
import System.Collections.*;
import System.Collections.CollectionBase.*;
public class Int16Collection extends CollectionBase
{
/** @property
*/
public short get_Value(int index)
{
short s = System.Convert.ToInt16(get_List().get_Item(index));
return(s) ;
} //get_Value
/** @property
*/
public void set_Value(int index,short value)
{
get_List().set_Item(index, (Int16)value);
} //set_Value
public int Add(short value)
{
return get_List().Add((Int16)value);
} //Add
public int IndexOf(short value)
{
return get_List().IndexOf((Int16)value);
} //IndexOf
public void Insert(int index, short value)
{
get_List().Insert(index, (Int16)value);
} //Insert
public void Remove(short value)
{
get_List().Remove((Int16)value);
} //Remove
public boolean Contains(short value)
{
// If value is not of type Int16, this will return false.
return get_List().Contains((Int16)value);
} //Contains
protected void OnInsert(int index, Object value)
{
// Insert additional code to be run only when inserting values.
} //OnInsert
protected void OnRemove(int index, Object value)
{
// Insert additional code to be run only when removing values.
} //OnRemove
protected void OnSet(int index, Object oldValue, Object newValue)
{
// Insert additional code to be run only when setting values.
} //OnSet
protected void OnValidate(Object value)
{
if ( value.GetType() != Type.GetType("System.Int16") ) {
throw new ArgumentException("value must be of type Int16.",
"value");
}
} //OnValidate
} //Int16Collection
public class SamplesCollectionBase
{
public static void main(String[] args)
{
// Create and initialize a new CollectionBase.
Int16Collection myI16 = new Int16Collection();
// Add elements to the collection.
myI16.Add((Int16)1);
myI16.Add((Int16)2);
myI16.Add((Int16)3);
myI16.Add((Int16)5);
myI16.Add((Int16)7);
// Display the contents of the collection using for.
Console.WriteLine("Contents of the collection (using for):");
PrintValues1(myI16);
// Display the contents of the collection using the enumerator.
Console.WriteLine("Contents of the collection (using enumerator):");
PrintValues2(myI16);
// Display the contents of the collection using the Count property and
// the Item property.
Console.WriteLine("Initial contents of the collection "
+ "(using Count and Item):");
PrintIndexAndValues(myI16);
// Search the collection with Contains and IndexOf.
Console.WriteLine("Contains 3: {0}",
(System.Boolean)myI16.Contains((Int16)3));
Console.WriteLine("2 is at index {0}.",
(Int16)myI16.IndexOf((Int16)2));
Console.WriteLine();
// Insert an element into the collection at index 3.
myI16.Insert(3, (Int16)13);
Console.WriteLine("Contents of the collection after inserting at"
+ " index 3:");
PrintIndexAndValues(myI16);
// Get and set an element using the index.
myI16 .set_Item( 4 ,(Int16)123 );
Console.WriteLine("Contents of the collection after setting the"
+ " element at index 4 to 123:");
PrintIndexAndValues(myI16);
// Remove an element from the collection.
myI16.Remove((Int16)2);
// Display the contents of the collection using the Count property and
// the Item property.
Console.WriteLine("Contents of the collection after removing the"
+ " element 2:");
PrintIndexAndValues(myI16);
} //main
// Uses the Count property and the Item property.
public static void PrintIndexAndValues(Int16Collection myCol)
{
for(int i = 0; i < myCol.get_Count(); i++) {
Console.WriteLine(" [{0}]: {1}", (Int32)i,
myCol.get_Item(i));
}
Console.WriteLine();
} //PrintIndexAndValues
// Uses the for statement which hides the complexity of the enumerator.
// NOTE: The for statement is the preferred way of enumerating the contents
// of a collection.
public static void PrintValues1(Int16Collection myCol)
{
for (int iCtr = 0; iCtr < myCol.get_Count(); iCtr++) {
Console.WriteLine(" {0}", myCol.get_Item(iCtr));
}
Console.WriteLine();
} //PrintValues1
// Uses the enumerator.
// NOTE: The for statement is the preferred way of enumerating the contents
// of a collection.
public static void PrintValues2(Int16Collection myCol)
{
System.Collections.IEnumerator myEnumerator = myCol.GetEnumerator();
while(myEnumerator.MoveNext()) {
Console.WriteLine(" {0}", myEnumerator.get_Current());
}
Console.WriteLine();
} //PrintValues2
} //SamplesCollectionBase
/*
Contents of the collection (using for):
1
2
3
5
7
Contents of the collection (using enumerator):
1
2
3
5
7
Initial contents of the collection (using Count and Item):
[0]: 1
[1]: 2
[2]: 3
[3]: 5
[4]: 7
Contains 3: True
2 is at index 1.
Contents of the collection after inserting at index 3:
[0]: 1
[1]: 2
[2]: 3
[3]: 13
[4]: 5
[5]: 7
Contents of the collection after setting the element at index 4 to 123:
[0]: 1
[1]: 2
[2]: 3
[3]: 13
[4]: 123
[5]: 7
Contents of the collection after removing the element 2:
[0]: 1
[1]: 3
[2]: 13
[3]: 123
[4]: 7
*/
平台
Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。
版本信息
.NET Framework
受以下版本支持：2.0、1.1、1.0
.NET Compact Framework
受以下版本支持：2.0、1.0
请参见
参考
CollectionBase 类
CollectionBase 成员
System.Collections 命名空间
OnSet
OnInsert