ArrayList.Sort ArrayList.Sort ArrayList.Sort ArrayList.Sort Method

Definition

Sorts the elements in the ArrayList or a portion of it.

Overloads

Sort() Sort() Sort() Sort()

Sorts the elements in the entire ArrayList.

Sort(IComparer) Sort(IComparer) Sort(IComparer) Sort(IComparer)

Sorts the elements in the entire ArrayList using the specified comparer.

Sort(Int32, Int32, IComparer) Sort(Int32, Int32, IComparer) Sort(Int32, Int32, IComparer) Sort(Int32, Int32, IComparer)

Sorts the elements in a range of elements in ArrayList using the specified comparer.

Sort() Sort() Sort() Sort()

Sorts the elements in the entire ArrayList.

public:
 virtual void Sort();
public virtual void Sort ();
abstract member Sort : unit -> unit
override this.Sort : unit -> unit
Public Overridable Sub Sort ()

Exceptions

Examples

The following code example shows how to sort the values in an 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 values of the ArrayList.
   Console::WriteLine( "The ArrayList initially contains the following values:" );
   PrintValues( myAL );
   
   // Sorts the values of the ArrayList.
   myAL->Sort();
   
   // Displays the values of the ArrayList.
   Console::WriteLine( "After sorting:" );
   PrintValues( myAL );
}

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

   Console::WriteLine();
}

/* 
 This code produces the following output.

 The ArrayList initially contains the following values:
    The
    quick
    brown
    fox
    jumps
    over
    the
    lazy
    dog

 After sorting:
    brown
    dog
    fox
    jumps
    lazy
    over
    quick
    the
    The
 */
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 values of the ArrayList.
      Console.WriteLine( "The ArrayList initially contains the following values:" );
      PrintValues( myAL );

      // Sorts the values of the ArrayList.
      myAL.Sort();

      // Displays the values of the ArrayList.
      Console.WriteLine( "After sorting:" );
      PrintValues( myAL );
   }

   public static void PrintValues( IEnumerable myList )  {
      foreach ( Object obj in myList )
         Console.WriteLine( "   {0}", obj );
      Console.WriteLine();
   }

}


/* 
This code produces the following output.

The ArrayList initially contains the following values:
   The
   quick
   brown
   fox
   jumps
   over
   the
   lazy
   dog

After sorting:
   brown
   dog
   fox
   jumps
   lazy
   over
   quick
   the
   The
*/
Imports System
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 values of the ArrayList.
        Console.WriteLine("The ArrayList initially contains the following values:")
        PrintValues(myAL)

        ' Sorts the values of the ArrayList.
        myAL.Sort()

        ' Displays the values of the ArrayList.
        Console.WriteLine("After sorting:")
        PrintValues(myAL)

    End Sub 'Main

    Public Shared Sub PrintValues(myList As IEnumerable)
        Dim obj As [Object]
        For Each obj In  myList
            Console.WriteLine("   {0}", obj)
        Next obj
        Console.WriteLine()
    End Sub 'PrintValues

End Class 'SamplesArrayList 


' This code produces the following output.
'
' The ArrayList initially contains the following values:
'    The
'    quick
'    brown
'    fox
'    jumps
'    over
'    the
'    lazy
'    dog
'
' After sorting:
'    brown
'    dog
'    fox
'    jumps
'    lazy
'    over
'    quick
'    the
'    The

Remarks

This method uses Array.Sort, which uses the QuickSort algorithm. The QuickSort algorithm is a comparison sort (also called an unstable sort), which means that a "less than or equal to" comparison operation determines which of two elements should occur first in the final sorted list. However, if two elements are equal, their original order might not be preserved. In contrast, a stable sort preserves the order of elements that are equal. To perform a stable sort, you must implement a custom IComparer interface to use with the other overloads of this method.

On average, this method is an O(n log n) operation, where n is Count; in the worst case it is an O(n^2) operation.

See Also

Sort(IComparer) Sort(IComparer) Sort(IComparer) Sort(IComparer)

Sorts the elements in the entire ArrayList using the specified comparer.

public:
 virtual void Sort(System::Collections::IComparer ^ comparer);
public virtual void Sort (System.Collections.IComparer comparer);
abstract member Sort : System.Collections.IComparer -> unit
override this.Sort : System.Collections.IComparer -> unit
Public Overridable Sub Sort (comparer As IComparer)

Parameters

comparer
IComparer IComparer IComparer IComparer

The IComparer implementation to use when comparing elements.

-or-

A null reference (Nothing in Visual Basic) to use the IComparable implementation of each element.

Exceptions

null is passed for comparer, and the elements in the list do not implement IComparable.

Examples

The following code example shows how to sort the values in an ArrayList using the default comparer and a custom comparer that reverses the sort order.

using namespace System;
using namespace System::Collections;
void PrintIndexAndValues( IEnumerable^ myList );
ref class myReverserClass: public IComparer
{
private:

   // Calls CaseInsensitiveComparer.Compare with the parameters reversed.
   virtual int Compare( Object^ x, Object^ y ) sealed = IComparer::Compare
   {
      return ((gcnew CaseInsensitiveComparer)->Compare( y, x ));
   }

};

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 values of the ArrayList.
   Console::WriteLine( "The ArrayList initially contains the following values:" );
   PrintIndexAndValues( myAL );
   
   // Sorts the values of the ArrayList using the default comparer.
   myAL->Sort();
   Console::WriteLine( "After sorting with the default comparer:" );
   PrintIndexAndValues( myAL );
   
   // Sorts the values of the ArrayList using the reverse case-insensitive comparer.
   IComparer^ myComparer = gcnew myReverserClass;
   myAL->Sort( myComparer );
   Console::WriteLine( "After sorting with the reverse case-insensitive comparer:" );
   PrintIndexAndValues( myAL );
}

void PrintIndexAndValues( IEnumerable^ myList )
{
   int i = 0;
   IEnumerator^ myEnum = myList->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      Console::WriteLine( "\t[{0}]:\t{1}", i++, obj );
   }

   Console::WriteLine();
}

/* 
This code produces the following output.
The ArrayList initially contains the following values:
        [0]:    The
        [1]:    quick
        [2]:    brown
        [3]:    fox
        [4]:    jumps
        [5]:    over
        [6]:    the
        [7]:    lazy
        [8]:    dog

After sorting with the default comparer:
        [0]:    brown
        [1]:    dog
        [2]:    fox
        [3]:    jumps
        [4]:    lazy
        [5]:    over
        [6]:    quick
        [7]:    the
        [8]:    The

After sorting with the reverse case-insensitive comparer:
        [0]:    the
        [1]:    The
        [2]:    quick
        [3]:    over
        [4]:    lazy
        [5]:    jumps
        [6]:    fox
        [7]:    dog
        [8]:    brown 
*/
using System;
using System.Collections;

public class SamplesArrayList  {
 
   public class myReverserClass : IComparer  {

      // Calls CaseInsensitiveComparer.Compare with the parameters reversed.
      int IComparer.Compare( Object x, Object y )  {
          return( (new CaseInsensitiveComparer()).Compare( y, x ) );
      }

   }

   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 values of the ArrayList.
      Console.WriteLine( "The ArrayList initially contains the following values:" );
      PrintIndexAndValues( myAL );
 
      // Sorts the values of the ArrayList using the default comparer.
      myAL.Sort();
      Console.WriteLine( "After sorting with the default comparer:" );
      PrintIndexAndValues( myAL );

      // Sorts the values of the ArrayList using the reverse case-insensitive comparer.
      IComparer myComparer = new myReverserClass();
      myAL.Sort( myComparer );
      Console.WriteLine( "After sorting with the reverse case-insensitive comparer:" );
      PrintIndexAndValues( myAL );

   }
 
   public static void PrintIndexAndValues( IEnumerable myList )  {
      int i = 0;
      foreach ( Object obj in myList )
         Console.WriteLine( "\t[{0}]:\t{1}", i++, obj );
      Console.WriteLine();
   }

}


/* 
This code produces the following output.
The ArrayList initially contains the following values:
        [0]:    The
        [1]:    quick
        [2]:    brown
        [3]:    fox
        [4]:    jumps
        [5]:    over
        [6]:    the
        [7]:    lazy
        [8]:    dog

After sorting with the default comparer:
        [0]:    brown
        [1]:    dog
        [2]:    fox
        [3]:    jumps
        [4]:    lazy
        [5]:    over
        [6]:    quick
        [7]:    the
        [8]:    The

After sorting with the reverse case-insensitive comparer:
        [0]:    the
        [1]:    The
        [2]:    quick
        [3]:    over
        [4]:    lazy
        [5]:    jumps
        [6]:    fox
        [7]:    dog
        [8]:    brown 
*/

Imports System
Imports System.Collections
Imports Microsoft.VisualBasic

Public Class SamplesArrayList

   Public Class myReverserClass
      Implements IComparer

      ' Calls CaseInsensitiveComparer.Compare with the parameters reversed.
      Public Function Compare( ByVal x As Object, ByVal y As Object) As Integer _
         Implements IComparer.Compare
         Return New CaseInsensitiveComparer().Compare(y, x)
      End Function 'IComparer.Compare

   End Class 'myReverserClass

   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 values of the ArrayList.
      Console.WriteLine("The ArrayList initially contains the following values:")
      PrintIndexAndValues(myAL)

      ' Sorts the values of the ArrayList using the default comparer.
      myAL.Sort()
      Console.WriteLine("After sorting with the default comparer:")
      PrintIndexAndValues(myAL)

      ' Sorts the values of the ArrayList using the reverse case-insensitive comparer.
      Dim myComparer = New myReverserClass()
      myAL.Sort(myComparer)
      Console.WriteLine("After sorting with the reverse case-insensitive comparer:")
      PrintIndexAndValues(myAL)

   End Sub 'Main

   Public Shared Sub PrintIndexAndValues(myList As IEnumerable)
      Dim i As Integer = 0
      Dim obj As [Object]
      For Each obj In  myList
         Console.WriteLine(vbTab + "[{0}]:" + vbTab + "{1}", i, obj)
         i = i + 1
      Next obj
      Console.WriteLine()
   End Sub 'PrintIndexAndValues

End Class 'SamplesArrayList


'This code produces the following output.
'The ArrayList initially contains the following values:
'        [0]:    The
'        [1]:    quick
'        [2]:    brown
'        [3]:    fox
'        [4]:    jumps
'        [5]:    over
'        [6]:    the
'        [7]:    lazy
'        [8]:    dog
'
'After sorting with the default comparer:
'        [0]:    brown
'        [1]:    dog
'        [2]:    fox
'        [3]:    jumps
'        [4]:    lazy
'        [5]:    over
'        [6]:    quick
'        [7]:    the
'        [8]:    The
'
'After sorting with the reverse case-insensitive comparer:
'        [0]:    the
'        [1]:    The
'        [2]:    quick
'        [3]:    over
'        [4]:    lazy
'        [5]:    jumps
'        [6]:    fox
'        [7]:    dog
'        [8]:    brown

Remarks

Use the Sort method to sort a list of objects with a custom comparer that implements the IComparer interface. If you pass null for comparer, this method uses the IComparable implementation of each element. In this case, you must make sure that the objects contained in the list implement the IComparer interface or an exception will occur.

In addition, using the IComparable implementation means the list performs a comparison sort (also called an unstable sort); that is, if two elements are equal, their order might not be preserved. In contrast, a stable sort preserves the order of elements that are equal. To perform a stable sort, you must implement a custom IComparer interface.

On average, this method is an O(n log n) operation, where n is Count; in the worst case it is an O(n^2) operation.

See Also

Sort(Int32, Int32, IComparer) Sort(Int32, Int32, IComparer) Sort(Int32, Int32, IComparer) Sort(Int32, Int32, IComparer)

Sorts the elements in a range of elements in ArrayList using the specified comparer.

public:
 virtual void Sort(int index, int count, System::Collections::IComparer ^ comparer);
public virtual void Sort (int index, int count, System.Collections.IComparer comparer);
abstract member Sort : int * int * System.Collections.IComparer -> unit
override this.Sort : int * int * System.Collections.IComparer -> unit
Public Overridable Sub Sort (index As Integer, count As Integer, comparer As IComparer)

Parameters

index
Int32 Int32 Int32 Int32

The zero-based starting index of the range to sort.

count
Int32 Int32 Int32 Int32

The length of the range to sort.

comparer
IComparer IComparer IComparer IComparer

The IComparer implementation to use when comparing elements.

-or-

A null reference (Nothing in Visual Basic) to use the IComparable implementation of each element.

Exceptions

index and count do not specify a valid range in the ArrayList.

Examples

The following code example shows how to sort the values in a range of elements in an ArrayList using the default comparer and a custom comparer that reverses the sort order.

using namespace System;
using namespace System::Collections;
void PrintIndexAndValues( IEnumerable^ myList );
ref class myReverserClass: public IComparer
{
private:

   // Calls CaseInsensitiveComparer.Compare with the parameters reversed.
   virtual int Compare( Object^ x, Object^ y ) = IComparer::Compare
   {
      return ((gcnew CaseInsensitiveComparer)->Compare( y, x ));
   }

};

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 values of the ArrayList.
   Console::WriteLine( "The ArrayList initially contains the following values:" );
   PrintIndexAndValues( myAL );
   
   // Sorts the values of the ArrayList using the default comparer.
   myAL->Sort( 1, 3, nullptr );
   Console::WriteLine( "After sorting from index 1 to index 3 with the default comparer:" );
   PrintIndexAndValues( myAL );
   
   // Sorts the values of the ArrayList using the reverse case-insensitive comparer.
   IComparer^ myComparer = gcnew myReverserClass;
   myAL->Sort( 1, 3, myComparer );
   Console::WriteLine( "After sorting from index 1 to index 3 with the reverse case-insensitive comparer:" );
   PrintIndexAndValues( myAL );
}

void PrintIndexAndValues( IEnumerable^ myList )
{
   int i = 0;
   IEnumerator^ myEnum = myList->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      Console::WriteLine( "\t[{0}]:\t{1}", i++, obj );
   }

   Console::WriteLine();
}

/* 
This code produces the following output.
The ArrayList initially contains the following values:
        [0]:    The
        [1]:    QUICK
        [2]:    BROWN
        [3]:    FOX
        [4]:    jumps
        [5]:    over
        [6]:    the
        [7]:    lazy
        [8]:    dog

After sorting from index 1 to index 3 with the default comparer:
        [0]:    The
        [1]:    BROWN
        [2]:    FOX
        [3]:    QUICK
        [4]:    jumps
        [5]:    over
        [6]:    the
        [7]:    lazy
        [8]:    dog

After sorting from index 1 to index 3 with the reverse case-insensitive comparer:
        [0]:    The
        [1]:    QUICK
        [2]:    FOX
        [3]:    BROWN
        [4]:    jumps
        [5]:    over
        [6]:    the
        [7]:    lazy
        [8]:    dog
*/
using System;
using System.Collections;

public class SamplesArrayList  {

   public class myReverserClass : IComparer  {

      // Calls CaseInsensitiveComparer.Compare with the parameters reversed.
      int IComparer.Compare( Object x, Object y )  {
          return( (new CaseInsensitiveComparer()).Compare( y, x ) );
      }

   }

   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 values of the ArrayList.
      Console.WriteLine( "The ArrayList initially contains the following values:" );
      PrintIndexAndValues( myAL );

      // Sorts the values of the ArrayList using the default comparer.
      myAL.Sort( 1, 3, null );
      Console.WriteLine( "After sorting from index 1 to index 3 with the default comparer:" );
      PrintIndexAndValues( myAL );

      // Sorts the values of the ArrayList using the reverse case-insensitive comparer.
      IComparer myComparer = new myReverserClass();
      myAL.Sort( 1, 3, myComparer );
      Console.WriteLine( "After sorting from index 1 to index 3 with the reverse case-insensitive comparer:" );
      PrintIndexAndValues( myAL );

   }
 
   public static void PrintIndexAndValues( IEnumerable myList )  {
      int i = 0;
      foreach ( Object obj in myList )
         Console.WriteLine( "\t[{0}]:\t{1}", i++, obj );
      Console.WriteLine();
   }

}


/* 
This code produces the following output.
The ArrayList initially contains the following values:
        [0]:    The
        [1]:    QUICK
        [2]:    BROWN
        [3]:    FOX
        [4]:    jumps
        [5]:    over
        [6]:    the
        [7]:    lazy
        [8]:    dog

After sorting from index 1 to index 3 with the default comparer:
        [0]:    The
        [1]:    BROWN
        [2]:    FOX
        [3]:    QUICK
        [4]:    jumps
        [5]:    over
        [6]:    the
        [7]:    lazy
        [8]:    dog

After sorting from index 1 to index 3 with the reverse case-insensitive comparer:
        [0]:    The
        [1]:    QUICK
        [2]:    FOX
        [3]:    BROWN
        [4]:    jumps
        [5]:    over
        [6]:    the
        [7]:    lazy
        [8]:    dog
*/

Imports System
Imports System.Collections
Imports Microsoft.VisualBasic

Public Class SamplesArrayList

   Public Class myReverserClass
      Implements IComparer

      ' Calls CaseInsensitiveComparer.Compare with the parameters reversed.
      Public Function Compare( ByVal x As Object, ByVal y As Object) As Integer _
         Implements IComparer.Compare
         Return New CaseInsensitiveComparer().Compare(y, x)
      End Function 'IComparer.Compare

   End Class 'myReverserClass

   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 values of the ArrayList.
      Console.WriteLine("The ArrayList initially contains the following values:")
      PrintIndexAndValues(myAL)

      ' Sorts the values of the ArrayList using the default comparer.
      myAL.Sort(1, 3, Nothing)
      Console.WriteLine("After sorting from index 1 to index 3 with the default comparer:")
      PrintIndexAndValues(myAL)

      ' Sorts the values of the ArrayList using the reverse case-insensitive comparer.
      Dim myComparer = New myReverserClass()
      myAL.Sort(1, 3, myComparer)
      Console.WriteLine("After sorting from index 1 to index 3 with the reverse case-insensitive comparer:")
      PrintIndexAndValues(myAL)

   End Sub 'Main

   Public Shared Sub PrintIndexAndValues(myList As IEnumerable)
      Dim i As Integer = 0
      Dim obj As [Object]
      For Each obj In  myList
         Console.WriteLine(vbTab + "[{0}]:" + vbTab + "{1}", i, obj)
         i = i + 1
      Next obj
      Console.WriteLine()
   End Sub 'PrintIndexAndValues

End Class 'SamplesArrayList 


'This code produces the following output.
'The ArrayList initially contains the following values:
'        [0]:    The
'        [1]:    QUICK
'        [2]:    BROWN
'        [3]:    FOX
'        [4]:    jumps
'        [5]:    over
'        [6]:    the
'        [7]:    lazy
'        [8]:    dog
'
'After sorting from index 1 to index 3 with the default comparer:
'        [0]:    The
'        [1]:    BROWN
'        [2]:    FOX
'        [3]:    QUICK
'        [4]:    jumps
'        [5]:    over
'        [6]:    the
'        [7]:    lazy
'        [8]:    dog
'
'After sorting from index 1 to index 3 with the reverse case-insensitive comparer:
'        [0]:    The
'        [1]:    QUICK
'        [2]:    FOX
'        [3]:    BROWN
'        [4]:    jumps
'        [5]:    over
'        [6]:    the
'        [7]:    lazy
'        [8]:    dog

Remarks

If comparer is set to null, this method performs a comparison sort (also called an unstable sort); that is, if two elements are equal, their order might not be preserved. In contrast, a stable sort preserves the order of elements that are equal. To perform a stable sort, you must implement a custom IComparer interface.

On average, this method is an O(n log n) operation, where n is count; in the worst case it is an O(n^2) operation.

See Also

Applies to