NameObjectCollectionBase.BaseGet Method (String)
Assembly: System (in system.dll)
'Declaration Protected Function BaseGet ( _ name As String _ ) As Object 'Usage Dim name As String Dim returnValue As Object returnValue = Me.BaseGet(name)
protected Object BaseGet ( String name )
protected function BaseGet ( name : String ) : Object
Not applicable.
Parameters
- name
The String key of the entry to get. The key can be a null reference (Nothing in Visual Basic).
Return Value
An Object that represents the value of the first entry with the specified key, if found; otherwise, a null reference (Nothing in Visual Basic).If the collection contains multiple entries with the specified key, this method returns only the first entry. To get the values of subsequent entries with the same key, use the enumerator to iterate through the collection and compare the keys.
Caution: |
|---|
| This method returns a null reference (Nothing in Visual Basic) in the following cases: 1) if the specified key is not found; and 2) if the specified key is found and its associated value is a null reference (Nothing in Visual Basic). This method does not distinguish between the two cases. |
This method is an O(1) operation.
The following code example uses BaseGetKey and BaseGet to get specific keys and values.
Imports System Imports System.Collections Imports System.Collections.Specialized Public Class MyCollection Inherits NameObjectCollectionBase Private _de As New DictionaryEntry() ' Gets a key-and-value pair (DictionaryEntry) using an index. Default Public ReadOnly Property Item(index As Integer) As DictionaryEntry Get _de.Key = Me.BaseGetKey(index) _de.Value = Me.BaseGet(index) Return _de End Get End Property ' Gets or sets the value associated with the specified key. Default Public Property Item(key As [String]) As [Object] Get Return Me.BaseGet(key) End Get Set Me.BaseSet(key, value) End Set End Property ' Adds elements from an IDictionary into the new collection. Public Sub New(d As IDictionary) Dim de As DictionaryEntry For Each de In d Me.BaseAdd(CType(de.Key, [String]), de.Value) Next de End Sub 'New End Class 'MyCollection Public Class SamplesNameObjectCollectionBase Public Shared Sub Main() ' Creates and initializes a new MyCollection instance. Dim d = New ListDictionary() d.Add("red", "apple") d.Add("yellow", "banana") d.Add("green", "pear") Dim myCol As New MyCollection(d) Console.WriteLine("Initial state of the collection (Count = {0}):", myCol.Count) PrintKeysAndValues(myCol) ' Gets specific keys and values. Console.WriteLine("The key at index 0 is {0}.", myCol(0).Key) Console.WriteLine("The value at index 0 is {0}.", myCol(0).Value) Console.WriteLine("The value associated with the key ""green"" is {0}.", myCol("green")) End Sub 'Main Public Shared Sub PrintKeysAndValues(myCol As MyCollection) Dim i As Integer For i = 0 To myCol.Count - 1 Console.WriteLine("[{0}] : {1}, {2}", i, myCol(i).Key, myCol(i).Value) Next i End Sub 'PrintKeysAndValues End Class 'SamplesNameObjectCollectionBase 'This code produces the following output. ' 'Initial state of the collection (Count = 3): '[0] : red, apple '[1] : yellow, banana '[2] : green, pear 'The key at index 0 is red. 'The value at index 0 is apple. 'The value associated with the key "green" is pear.
import System.* ;
import System.Collections.* ;
import System.Collections.Specialized.* ;
public class MyCollection extends NameObjectCollectionBase
{
private DictionaryEntry _de = new DictionaryEntry();
// Gets a key-and-value pair (DictionaryEntry) using an index.
/** @property
*/
public DictionaryEntry get_Item(int index)
{
_de.set_Key(this.BaseGetKey(index));
_de.set_Value(this.BaseGet(index));
return _de ;
} //get_Item
// Gets or sets the value associated with the specified key.
/** @property
*/
public Object get_Item(String key)
{
return this.BaseGet(key) ;
} //get_Item
/** @property
*/
public void set_Item(String key,Object value )
{
this.BaseSet(key, value);
} //set_Item
//default constructor
public MyCollection()
{
} //MyCollection
// Adds elements from an IDictionary into the new collection.
public MyCollection(IDictionary d)
{
IDictionaryEnumerator objEnum = d.GetEnumerator();
while(objEnum.MoveNext()) {
DictionaryEntry de = (DictionaryEntry)objEnum.get_Current();
this.BaseAdd(((String)(de.get_Key())), de.get_Value());
}
} //MyCollection
} //MyCollection
public class SamplesNameObjectCollectionBase
{
public static void main(String[] args)
{
// Creates and initializes a new MyCollection instance.
IDictionary d = new ListDictionary();
d.Add("red", "apple");
d.Add("yellow", "banana");
d.Add("green", "pear");
MyCollection myCol = new MyCollection(d);
Console.WriteLine("Initial state of the collection (Count = {0}):",
System.Convert.ToString(myCol.get_Count()));
PrintKeysAndValues(myCol);
// Gets specific keys and values.
Console.WriteLine("The key at index 0 is {0}.",
myCol.get_Item( 0).get_Key());
Console.WriteLine("The value at index 0 is {0}.",
myCol.get_Item( 0).get_Value());
Console.WriteLine("The value associated with the key \"green\" is {0}.",
myCol.get_Item( "green"));
} //main
public static void PrintKeysAndValues(MyCollection myCol)
{
for (int i=0 ; i < myCol.get_Count(); i++) {
Console.WriteLine("[{0}] : {1}, {2}", System.Convert.ToString(i),
myCol.get_Item(i).get_Key(), myCol.get_Item(i).get_Value());
}
} //PrintKeysAndValues
} //SamplesNameObjectCollectionBase
/*
This code produces the following output.
Initial state of the collection (Count = 3):
[0] : red, apple
[1] : yellow, banana
[2] : green, pear
The key at index 0 is red.
The value at index 0 is apple.
The value associated with the key "green" is pear.
*/
Windows 98, Windows Server 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
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.
Caution: