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NameObjectCollectionBase.BaseHasKeys-Methode

Aktualisiert: November 2007

Ruft einen Wert ab, der angibt, ob die NameObjectCollectionBase-Instanz Einträge enthält, deren Schlüssel nicht null ist.

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

protected bool BaseHasKeys()
protected boolean BaseHasKeys()
protected function BaseHasKeys() : boolean

Rückgabewert

Typ: System.Boolean
true, wenn die NameObjectCollectionBase-Instanz Einträge enthält, deren Schlüssel nicht null sind, andernfalls false.

Diese Methode ist eine O(1)-Operation.

Im folgenden Codebeispiel wird mit BaseHasKeys bestimmt, ob die Auflistung Schlüssel enthält, die nicht null sind.

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 );
      }
   }

   // Creates an empty collection.
   public MyCollection()  {
   }

   // Adds an entry to the collection.
   public void Add( String key, Object value )  {
      this.BaseAdd( key, value );
   }

   // Gets a value indicating whether the collection contains keys that are not a null reference.
   public Boolean HasKeys  {
      get  {
         return( this.BaseHasKeys() );
      }
   }

}

public class SamplesNameObjectCollectionBase  {

   public static void Main()  {

      // Creates an empty MyCollection instance.
      MyCollection myCol = new MyCollection();
      Console.WriteLine( "Initial state of the collection (Count = {0}):", myCol.Count );
      PrintKeysAndValues( myCol );
      Console.WriteLine( "HasKeys? {0}", myCol.HasKeys );

      Console.WriteLine();

      // Adds an item to the collection.
      myCol.Add( "blue", "sky" );
      Console.WriteLine( "Initial state of the collection (Count = {0}):", myCol.Count );
      PrintKeysAndValues( myCol );
      Console.WriteLine( "HasKeys? {0}", myCol.HasKeys );

   }

   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 = 0):
HasKeys? False

Initial state of the collection (Count = 1):
[0] : blue, sky
HasKeys? True

*/


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

    // Creates an empty collection.
    public MyCollection()
    {
    } //MyCollection

    // Adds an entry to the collection.
    public void Add(String key, Object value) 
    {
        this.BaseAdd(key, value);
    } //Add

    // Gets a value indicating whether the collection contains keys that are
    // not a null reference.
    /** @property 
     */
    public boolean get_HasKeys()
    {
        return this.BaseHasKeys() ;
    } //get_HasKeys
} //MyCollection


public class SamplesNameObjectCollectionBase
{
    public static void main(String[] args)
    {            
        // Creates an empty MyCollection instance.
        MyCollection myCol =  new MyCollection();
        Console.WriteLine("Initial state of the collection (Count = {0}):",
            System.Convert.ToString( myCol.get_Count()));
        PrintKeysAndValues(myCol);
        Console.WriteLine("HasKeys? {0}", 
            System.Convert.ToString(myCol.get_HasKeys()));
        Console.WriteLine();

        // Adds an item to the collection.
        myCol.Add("blue", "sky");
        Console.WriteLine("Initial state of the collection (Count = {0}):",
            System.Convert.ToString(myCol.get_Count()));
        PrintKeysAndValues(myCol);
        Console.WriteLine("HasKeys? {0}",
            System.Convert.ToString(myCol.get_HasKeys()));
    } //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 = 0):
HasKeys? False

Initial state of the collection (Count = 1):
[0] : blue, sky
HasKeys? True

*/


Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile für Smartphone, Windows Mobile für Pocket PC, Xbox 360

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