ArrayList.RemoveAt(Int32) Metoda

  • Reference

Definice

Obor názvů:
System.Collections
Sestavení:
mscorlib.dll, System.Collections.NonGeneric.dll
Sestavení:
System.Runtime.dll
Sestavení:
System.Collections.NonGeneric.dll
Sestavení:
System.Runtime.Extensions.dll
Sestavení:
mscorlib.dll
Sestavení:
netstandard.dll
Zdroj:
ArrayList.cs
Zdroj:
ArrayList.cs
Zdroj:
ArrayList.cs

Odebere prvek v zadaném indexu objektu ArrayList.

public:
 virtual void RemoveAt(int index);
public virtual void RemoveAt (int index);
abstract member RemoveAt : int -> unit
override this.RemoveAt : int -> unit
Public Overridable Sub RemoveAt (index As Integer)

Parametry

index
Int32

Index od nuly elementu, který se má odebrat.

Implementuje

RemoveAt(Int32)

Výjimky

ArgumentOutOfRangeException

Hodnota index je menší než nula.

-nebo-

index je rovno nebo větší než Count.

NotSupportedException

Je ArrayList jen pro čtení.

-nebo-

Má ArrayList pevnou velikost.

Příklady

Následující příklad kódu ukazuje, jak odebrat elementy z objektu ArrayList.

using namespace System;
using namespace System::Collections;
void PrintValues( IEnumerable^ myList );
int main()
{
   
   // Creates and initializes a new ArrayList.
   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" );
   
   // Displays the ArrayList.
   Console::WriteLine( "The ArrayList initially contains the following:" );
   PrintValues( myAL );
   
   // Removes the element containing "lazy".
   myAL->Remove( "lazy" );
   
   // Displays the current state of the ArrayList.
   Console::WriteLine( "After removing \"lazy\":" );
   PrintValues( myAL );
   
   // Removes the element at index 5.
   myAL->RemoveAt( 5 );
   
   // Displays the current state of the ArrayList.
   Console::WriteLine( "After removing the element at index 5:" );
   PrintValues( myAL );
   
   // Removes three elements starting at index 4.
   myAL->RemoveRange( 4, 3 );
   
   // Displays the current state of the ArrayList.
   Console::WriteLine( "After removing three elements starting at index 4:" );
   PrintValues( myAL );
}

void PrintValues( IEnumerable^ myList )
{
   IEnumerator^ myEnum = myList->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      Console::Write( "   {0}", obj );
   }

   Console::WriteLine();
}

/* 
 This code produces the following output.
 
 The ArrayList initially contains the following:
    The   quick   brown   fox   jumps   over   the   lazy   dog
 After removing "lazy":
    The   quick   brown   fox   jumps   over   the   dog
 After removing the element at index 5:
    The   quick   brown   fox   jumps   the   dog
 After removing three elements starting at index 4:
    The   quick   brown   fox
 */

using System;
using System.Collections;
public class SamplesArrayList  {

   public static void Main()  {

      // Creates and initializes a new ArrayList.
      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" );

      // Displays the ArrayList.
      Console.WriteLine( "The ArrayList initially contains the following:" );
      PrintValues( myAL );

      // Removes the element containing "lazy".
      myAL.Remove( "lazy" );

      // Displays the current state of the ArrayList.
      Console.WriteLine( "After removing \"lazy\":" );
      PrintValues( myAL );

      // Removes the element at index 5.
      myAL.RemoveAt( 5 );

      // Displays the current state of the ArrayList.
      Console.WriteLine( "After removing the element at index 5:" );
      PrintValues( myAL );

      // Removes three elements starting at index 4.
      myAL.RemoveRange( 4, 3 );

      // Displays the current state of the ArrayList.
      Console.WriteLine( "After removing three elements starting at index 4:" );
      PrintValues( myAL );
   }

   public static void PrintValues( IEnumerable myList )  {
      foreach ( Object obj in myList )
         Console.Write( "   {0}", obj );
      Console.WriteLine();
   }
}
/*
This code produces the following output.

The ArrayList initially contains the following:
   The   quick   brown   fox   jumps   over   the   lazy   dog
After removing "lazy":
   The   quick   brown   fox   jumps   over   the   dog
After removing the element at index 5:
   The   quick   brown   fox   jumps   the   dog
After removing three elements starting at index 4:
   The   quick   brown   fox
*/

Imports System.Collections

Public Class SamplesArrayList    
    
    Public Shared Sub Main()
        
        ' Creates and initializes a new ArrayList.
        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")
        
        ' Displays the ArrayList.
        Console.WriteLine("The ArrayList initially contains the following:")
        PrintValues(myAL)
        
        ' Removes the element containing "lazy".
        myAL.Remove("lazy")
        
        ' Displays the current state of the ArrayList.
        Console.WriteLine("After removing ""lazy"":")
        PrintValues(myAL)
        
        ' Removes the element at index 5.
        myAL.RemoveAt(5)
        
        ' Displays the current state of the ArrayList.
        Console.WriteLine("After removing the element at index 5:")
        PrintValues(myAL)
        
        ' Removes three elements starting at index 4.
        myAL.RemoveRange(4, 3)
        
        ' Displays the current state of the ArrayList.
        Console.WriteLine("After removing three elements starting at index 4:")
        PrintValues(myAL)
    End Sub
    
    Public Shared Sub PrintValues(myList As IEnumerable)
        Dim obj As [Object]
        For Each obj In  myList
            Console.Write("   {0}", obj)
        Next obj
        Console.WriteLine()
    End Sub

End Class


' This code produces the following output.
' 
' The ArrayList initially contains the following:
'    The   quick   brown   fox   jumps   over   the   lazy   dog
' After removing "lazy":
'    The   quick   brown   fox   jumps   over   the   dog
' After removing the element at index 5:
'    The   quick   brown   fox   jumps   the   dog
' After removing three elements starting at index 4:
'    The   quick   brown   fox

Poznámky

Po odebrání elementu se upraví velikost kolekce a hodnota Count vlastnosti se sníží o jednu.

V kolekcích souvislých prvků, tj. například v seznamech, se prvky následující po odebraném prvku posouvají nahoru tak, aby obsadily uvolněné místo. Je-li kolekce indexována, budou aktualizovány rovněž indexy přesunutých prvků. Toto chování se nevztahuje na kolekce, kde prvky jsou koncepčně seskupeny do sad, tj. například na tabulky hash.

Tato metoda je O(n) operace, kde n je Count.

Platí pro

Viz také