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NameObjectCollectionBase.BaseGetKey Method

Gets the key of the entry at the specified index of the NameObjectCollectionBase instance.

Namespace: System.Collections.Specialized
Assembly: System (in system.dll)

protected string BaseGetKey (
	int index
)
protected String BaseGetKey (
	int index
)
protected function BaseGetKey (
	index : int
) : String
Not applicable.

Parameters

index

The zero-based index of the key to get.

Return Value

A String that represents the key of the entry at the specified index.

Exception typeCondition

ArgumentOutOfRangeException

index is outside the valid range of indexes for the collection.

This method is an O(1) operation.

The following code example uses BaseGetKey and BaseGet to get specific keys and values.

using System;
using System.Collections;
using System.Collections.Specialized;

public class MyCollection : NameObjectCollectionBase  {

   private DictionaryEntry _de = new DictionaryEntry();

   // Gets a key-and-value pair (DictionaryEntry) using an index.
   public DictionaryEntry this[ int index ]  {
      get  {
         _de.Key = this.BaseGetKey( index );
         _de.Value = this.BaseGet( index );
         return( _de );
      }
   }

   // Gets or sets the value associated with the specified key.
   public Object this[ String key ]  {
      get  {
         return( this.BaseGet( key ) );
      }
      set  {
         this.BaseSet( key, value );
      }
   }

   // Adds elements from an IDictionary into the new collection.
   public MyCollection( IDictionary d )  {
      foreach ( DictionaryEntry de in d )  {
         this.BaseAdd( (String) de.Key, de.Value );
      }
   }

}

public class SamplesNameObjectCollectionBase  {

   public static void Main()  {

      // 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}):", 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"] );

   }

   public static void PrintKeysAndValues( MyCollection myCol )  {
      for ( int i = 0; i < myCol.Count; i++ )  {
         Console.WriteLine( "[{0}] : {1}, {2}", i, myCol[i].Key, myCol[i].Value );
      }
   }

}


/*
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.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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