SortedList Class
 

Represents a collection of key/value pairs that are sorted by the keys and are accessible by key and by index.

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

Inheritance Hierarchy
SystemObject
  System.CollectionsSortedList

Syntax
[SerializableAttribute]
[ComVisibleAttribute(true)]
public class SortedList : IDictionary, ICollection, IEnumerable, 
	ICloneable
[SerializableAttribute]
[ComVisibleAttribute(true)]
public ref class SortedList : IDictionary, ICollection, IEnumerable, 
	ICloneable
[<SerializableAttribute>]
[<ComVisibleAttribute(true)>]
type SortedList = 
    class
        interface IDictionary
        interface ICollection
        interface IEnumerable
        interface ICloneable
    end
<SerializableAttribute>
<ComVisibleAttribute(True)>
Public Class SortedList
	Implements IDictionary, ICollection, IEnumerable, ICloneable
Constructors
NameDescription
System_CAPS_pubmethod SortedList

Initializes a new instance of the SortedList class that is empty, has the default initial capacity, and is sorted according to the IComparable interface implemented by each key added to the SortedList object.

System_CAPS_pubmethod SortedList

Initializes a new instance of the SortedList class that is empty, has the default initial capacity, and is sorted according to the specified IComparer interface.

System_CAPS_pubmethod SortedList

Initializes a new instance of the SortedList class that is empty, has the specified initial capacity, and is sorted according to the specified IComparer interface.

System_CAPS_pubmethod SortedList

Initializes a new instance of the SortedList class that contains elements copied from the specified dictionary, has the same initial capacity as the number of elements copied, and is sorted according to the IComparable interface implemented by each key.

System_CAPS_pubmethod SortedList

Initializes a new instance of the SortedList class that contains elements copied from the specified dictionary, has the same initial capacity as the number of elements copied, and is sorted according to the specified IComparer interface.

System_CAPS_pubmethod SortedList

Initializes a new instance of the SortedList class that is empty, has the specified initial capacity, and is sorted according to the IComparable interface implemented by each key added to the SortedList object.

Properties
NameDescription
System_CAPS_pubproperty

Gets or sets the capacity of a SortedList object.

System_CAPS_pubproperty

Gets the number of elements contained in a SortedList object.

System_CAPS_pubproperty

Gets a value indicating whether a SortedList object has a fixed size.

System_CAPS_pubproperty

Gets a value indicating whether a SortedList object is read-only.

System_CAPS_pubproperty

Gets a value indicating whether access to a SortedList object is synchronized (thread safe).

System_CAPS_pubproperty

Gets and sets the value associated with a specific key in a SortedList object.

System_CAPS_pubproperty

Gets the keys in a SortedList object.

System_CAPS_pubproperty

Gets an object that can be used to synchronize access to a SortedList object.

System_CAPS_pubproperty

Gets the values in a SortedList object.

Methods
NameDescription
System_CAPS_pubmethod Add

Adds an element with the specified key and value to a SortedList object.

System_CAPS_pubmethod Clear

Removes all elements from a SortedList object.

System_CAPS_pubmethod Clone

Creates a shallow copy of a SortedList object.

System_CAPS_pubmethod Contains

Determines whether a SortedList object contains a specific key.

System_CAPS_pubmethod ContainsKey

Determines whether a SortedList object contains a specific key.

System_CAPS_pubmethod ContainsValue

Determines whether a SortedList object contains a specific value.

System_CAPS_pubmethod CopyTo

Copies SortedList elements to a one-dimensional Array object, starting at the specified index in the array.

System_CAPS_pubmethod Equals

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethod Finalize

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethod GetByIndex

Gets the value at the specified index of a SortedList object.

System_CAPS_pubmethod GetEnumerator

Returns an IDictionaryEnumerator object that iterates through a SortedList object.

System_CAPS_pubmethod GetHashCode

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethod GetKey

Gets the key at the specified index of a SortedList object.

System_CAPS_pubmethod GetKeyList

Gets the keys in a SortedList object.

System_CAPS_pubmethod GetType

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethod GetValueList

Gets the values in a SortedList object.

System_CAPS_pubmethod IndexOfKey

Returns the zero-based index of the specified key in a SortedList object.

System_CAPS_pubmethod IndexOfValue

Returns the zero-based index of the first occurrence of the specified value in a SortedList object.

System_CAPS_protmethod MemberwiseClone

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethod Remove

Removes the element with the specified key from a SortedList object.

System_CAPS_pubmethod RemoveAt

Removes the element at the specified index of a SortedList object.

System_CAPS_pubmethod SetByIndex

Replaces the value at a specific index in a SortedList object.

System_CAPS_pubmethod System_CAPS_static Synchronized

Returns a synchronized (thread-safe) wrapper for a SortedList object.

System_CAPS_pubmethod ToString

Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubmethod TrimToSize

Sets the capacity to the actual number of elements in a SortedList object.

Explicit Interface Implementations
NameDescription
System_CAPS_pubinterface System_CAPS_privmethod IEnumerableGetEnumerator

Returns an IEnumerator that iterates through the SortedList.

Extension Methods
NameDescription
System_CAPS_pubmethod AsParallel

Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.)

System_CAPS_pubmethod AsQueryable

Overloaded. Converts an IEnumerable to an IQueryable.(Defined by Queryable.)

System_CAPS_pubmethod Cast

Casts the elements of an IEnumerable to the specified type.(Defined by Enumerable.)

System_CAPS_pubmethod OfType

Filters the elements of an IEnumerable based on a specified type.(Defined by Enumerable.)

Remarks

For the generic version of this collection, see System.Collections.GenericSortedList.

A SortedList element can be accessed by its key, like an element in any IDictionary implementation, or by its index, like an element in any IList implementation.

A SortedList object internally maintains two arrays to store the elements of the list; that is, one array for the keys and another array for the associated values. Each element is a key/value pair that can be accessed as a DictionaryEntry object. A key cannot be null, but a value can be.

The capacity of a SortedList object is the number of elements the SortedList can hold. As elements are added to a SortedList, the capacity is automatically increased as required through reallocation. The capacity can be decreased by calling TrimToSize or by setting the property explicitly.

For very large SortedList objects, you can increase the maximum capacity to 2 billion elements on a 64-bit system by setting the enabled attribute of the configuration element to true in the run-time environment.

The elements of a SortedList object are sorted by the keys either according to a specific IComparer implementation specified when the SortedList is created or according to the IComparable implementation provided by the keys themselves. In either case, a SortedList does not allow duplicate keys.

The index sequence is based on the sort sequence. When an element is added, it is inserted into SortedList in the correct sort order, and the indexing adjusts accordingly. When an element is removed, the indexing also adjusts accordingly. Therefore, the index of a specific key/value pair might change as elements are added or removed from the SortedList object.

Operations on a SortedList object tend to be slower than operations on a Hashtable object because of the sorting. However, the SortedList offers more flexibility by allowing access to the values either through the associated keys or through the indexes.

Elements in this collection can be accessed using an integer index. Indexes in this collection are zero-based.

The foreach statement of the C# language (for each in Visual Basic) returns an object of the type of the elements in the collection. Since each element of the SortedList object is a key/value pair, the element type is not the type of the key or the type of the value. Rather, the element type is DictionaryEntry. For example:

foreach (DictionaryEntry de in mySortedList)
{
    //...
}
For Each de As DictionaryEntry In mySortedList
    '...
Next de
for each (DictionaryEntry de in mySortedList)
{
    //...
}

The foreach statement is a wrapper around the enumerator, which allows only reading from, not writing to, the collection.

Examples

The following code example shows how to create and initialize a SortedList object and how to print out its keys and values.

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

   public static void Main()  {

      // Creates and initializes a new SortedList.
      SortedList mySL = new SortedList();
       mySL.Add("Third", "!");
       mySL.Add("Second", "World");
       mySL.Add("First", "Hello");

      // Displays the properties and values of the SortedList.
      Console.WriteLine( "mySL" );
      Console.WriteLine( "  Count:    {0}", mySL.Count );
      Console.WriteLine( "  Capacity: {0}", mySL.Capacity );
      Console.WriteLine( "  Keys and Values:" );
      PrintKeysAndValues( mySL );
   }


   public static void PrintKeysAndValues( SortedList myList )  {
      Console.WriteLine( "\t-KEY-\t-VALUE-" );
      for ( int i = 0; i < myList.Count; i++ )  {
         Console.WriteLine( "\t{0}:\t{1}", myList.GetKey(i), myList.GetByIndex(i) );
      }
      Console.WriteLine();
   }
}
/*
This code produces the following output.

mySL
  Count:    3
  Capacity: 16
  Keys and Values:
    -KEY-    -VALUE-
    First:    Hello
    Second:    World
    Third:    !
*/
Imports System
Imports System.Collections
Imports Microsoft.VisualBasic

Public Class SamplesSortedList    

    Public Shared Sub Main()

        ' Creates and initializes a new SortedList.
        Dim mySL As New SortedList()
        mySL.Add("Third", "!")
        mySL.Add("Second", "World")
        mySL.Add("First", "Hello")

        ' Displays the properties and values of the SortedList.
        Console.WriteLine("mySL")
        Console.WriteLine("  Count:    {0}", mySL.Count)
        Console.WriteLine("  Capacity: {0}", mySL.Capacity)
        Console.WriteLine("  Keys and Values:")
        PrintKeysAndValues(mySL)
    End Sub

    Public Shared Sub PrintKeysAndValues(myList As SortedList)
        Console.WriteLine(ControlChars.Tab & "-KEY-" & ControlChars.Tab & _
           "-VALUE-")
        Dim i As Integer
        For i = 0 To myList.Count - 1
            Console.WriteLine(ControlChars.Tab & "{0}:" & ControlChars.Tab & _
               "{1}", myList.GetKey(i), myList.GetByIndex(i))
        Next i
        Console.WriteLine()
    End Sub
End Class

' This code produces the following output.
' 
' mySL
'   Count:    3
'   Capacity: 16
'   Keys and Values:
'     -KEY-     -VALUE-
'     First:    Hello
'     Second:   World
'     Third:    !
#using <system.dll>

using namespace System;
using namespace System::Collections;
public ref class SamplesSortedList
{
public:
   static void PrintKeysAndValues( SortedList^ myList )
   {
      Console::WriteLine( "\t-KEY-\t-VALUE-" );
      for ( int i = 0; i < myList->Count; i++ )
      {
         Console::WriteLine( "\t{0}:\t{1}", myList->GetKey( i ), myList->GetByIndex( i ) );

      }
      Console::WriteLine();
   }

};

int main()
{

   // Creates and initializes a new SortedList.
   SortedList^ mySL = gcnew SortedList;
   mySL->Add( "Third", "!" );
   mySL->Add( "Second", "World" );
   mySL->Add( "First", "Hello" );

   // Displays the properties and values of the SortedList.
   Console::WriteLine( "mySL" );
   Console::WriteLine( "  Count:    {0}", mySL->Count );
   Console::WriteLine( "  Capacity: {0}", mySL->Capacity );
   Console::WriteLine( "  Keys and Values:" );
   SamplesSortedList::PrintKeysAndValues( mySL );
}

/*
This code produces the following output.

mySL
Count:    3
Capacity: 16
Keys and Values:
-KEY-    -VALUE-
First:    Hello
Second:    World
Third:    !
*/
Version Information
Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Thread Safety

Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

A SortedList object can support multiple readers concurrently, as long as the collection is not modified. To guarantee the thread safety of the SortedList, all operations must be done through the wrapper returned by the Synchronized method.

Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

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