ArrayList.Add(Object) Method
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Adds an object to the end of the ArrayList.
public:
virtual int Add(System::Object ^ value);C#
public virtual int Add(object value);C#
public virtual int Add(object? value);abstract member Add : obj -> int
override this.Add : obj -> intPublic Overridable Function Add (value As Object) As IntegerThe ArrayList index at which the value has been added.
The following code example shows how to add elements to the ArrayList.
using namespace System;
using namespace System::Collections;
void PrintValues( IEnumerable^ myList, char mySeparator );
int main()
{
// Creates and initializes a new ArrayList.
ArrayList^ myAL = gcnew ArrayList;
myAL->Add( "The" );
myAL->Add( "quick" );
myAL->Add( "brown" );
myAL->Add( "fox" );
// Creates and initializes a new Queue.
Queue^ myQueue = gcnew Queue;
myQueue->Enqueue( "jumps" );
myQueue->Enqueue( "over" );
myQueue->Enqueue( "the" );
myQueue->Enqueue( "lazy" );
myQueue->Enqueue( "dog" );
// Displays the ArrayList and the Queue.
Console::WriteLine( "The ArrayList initially contains the following:" );
PrintValues( myAL, '\t' );
Console::WriteLine( "The Queue initially contains the following:" );
PrintValues( myQueue, '\t' );
// Copies the Queue elements to the end of the ArrayList.
myAL->AddRange( myQueue );
// Displays the ArrayList.
Console::WriteLine( "The ArrayList now contains the following:" );
PrintValues( myAL, '\t' );
}
void PrintValues( IEnumerable^ myList, char mySeparator )
{
IEnumerator^ myEnum = myList->GetEnumerator();
while ( myEnum->MoveNext() )
{
Object^ obj = safe_cast<Object^>(myEnum->Current);
Console::Write( "{0}{1}", mySeparator, obj );
}
Console::WriteLine();
}
/*
This code produces the following output.
The ArrayList initially contains the following:
The quick brown fox
The Queue initially contains the following:
jumps over the lazy dog
The ArrayList now contains the following:
The quick brown fox jumps over the lazy dog
*/
C#
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" );
// Creates and initializes a new Queue.
Queue myQueue = new Queue();
myQueue.Enqueue( "jumps" );
myQueue.Enqueue( "over" );
myQueue.Enqueue( "the" );
myQueue.Enqueue( "lazy" );
myQueue.Enqueue( "dog" );
// Displays the ArrayList and the Queue.
Console.WriteLine( "The ArrayList initially contains the following:" );
PrintValues( myAL, '\t' );
Console.WriteLine( "The Queue initially contains the following:" );
PrintValues( myQueue, '\t' );
// Copies the Queue elements to the end of the ArrayList.
myAL.AddRange( myQueue );
// Displays the ArrayList.
Console.WriteLine( "The ArrayList now contains the following:" );
PrintValues( myAL, '\t' );
}
public static void PrintValues( IEnumerable myList, char mySeparator ) {
foreach ( Object obj in myList )
Console.Write( "{0}{1}", mySeparator, obj );
Console.WriteLine();
}
}
/*
This code produces the following output.
The ArrayList initially contains the following:
The quick brown fox
The Queue initially contains the following:
jumps over the lazy dog
The ArrayList now contains the following:
The quick brown fox jumps over the lazy dog
*/
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")
' Creates and initializes a new Queue.
Dim myQueue As New Queue()
myQueue.Enqueue("jumps")
myQueue.Enqueue("over")
myQueue.Enqueue("the")
myQueue.Enqueue("lazy")
myQueue.Enqueue("dog")
' Displays the ArrayList and the Queue.
Console.WriteLine("The ArrayList initially contains the following:")
PrintValues(myAL, ControlChars.Tab)
Console.WriteLine("The Queue initially contains the following:")
PrintValues(myQueue, ControlChars.Tab)
' Copies the Queue elements to the end of the ArrayList.
myAL.AddRange(myQueue)
' Displays the ArrayList.
Console.WriteLine("The ArrayList now contains the following:")
PrintValues(myAL, ControlChars.Tab)
End Sub
Public Shared Sub PrintValues(myList As IEnumerable, mySeparator As Char)
Dim obj As [Object]
For Each obj In myList
Console.Write( "{0}{1}", mySeparator, 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
' The Queue initially contains the following:
' jumps over the lazy dog
' The ArrayList now contains the following:
' The quick brown fox jumps over the lazy dog
ArrayList accepts null as a valid value and allows duplicate elements.
If Count already equals Capacity, the capacity of the ArrayList is increased by automatically reallocating the internal array, and the existing elements are copied to the new array before the new element is added.
If Count is less than Capacity, this method is an O(1) operation. If the capacity needs to be increased to accommodate the new element, this method becomes an O(n) operation, where n is Count.
| Product | Versions |
|---|---|
| .NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 2.0, 2.1 |
| UWP | 10.0 |
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