SortedList Class

Definition

Namespace:

System.Collections

Assembly:

System.Collections.NonGeneric.dll

Source:

SortedList.cs

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

public ref class SortedList : ICloneable, System::Collections::IDictionary

public class SortedList : ICloneable, System.Collections.IDictionary

type SortedList = class
    interface ICollection
    interface IEnumerable
    interface IDictionary
    interface ICloneable

Public Class SortedList
Implements ICloneable, IDictionary

Inheritance

Object

SortedList

Implements

ICollection IDictionary IEnumerable ICloneable

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.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:    !
*/

using System;
using System.Collections;

public class SamplesSortedList2
{
    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.Collections

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:    !

Remarks

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.

Important

We don't recommend that you use the SortedList class for new development. Instead, we recommend that you use the generic System.Collections.Generic.SortedList<TKey,TValue> class. For more information, see Non-generic collections shouldn't be used on GitHub.

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 Capacity property explicitly.

.NET Framework only: 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 <gcAllowVeryLargeObjects> 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:

for each (DictionaryEntry de in mySortedList)
{
    //...
}

foreach (DictionaryEntry de in mySortedList)
{
    //...
}

For Each de As DictionaryEntry In mySortedList
    '...
Next de

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

Constructors

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.
SortedList(IComparer, Int32)	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.
SortedList(IComparer)	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.
SortedList(IDictionary, IComparer)	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.
SortedList(IDictionary)	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.
SortedList(Int32)	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

Capacity	Gets or sets the capacity of a SortedList object.
Count	Gets the number of elements contained in a SortedList object.
IsFixedSize	Gets a value indicating whether a SortedList object has a fixed size.
IsReadOnly	Gets a value indicating whether a SortedList object is read-only.
IsSynchronized	Gets a value indicating whether access to a SortedList object is synchronized (thread safe).
Item[Object]	Gets or sets the value associated with a specific key in a SortedList object.
Keys	Gets the keys in a SortedList object.
SyncRoot	Gets an object that can be used to synchronize access to a SortedList object.
Values	Gets the values in a SortedList object.

Methods

Add(Object, Object)	Adds an element with the specified key and value to a SortedList object.
Clear()	Removes all elements from a SortedList object.
Clone()	Creates a shallow copy of a SortedList object.
Contains(Object)	Determines whether a SortedList object contains a specific key.
ContainsKey(Object)	Determines whether a SortedList object contains a specific key.
ContainsValue(Object)	Determines whether a SortedList object contains a specific value.
CopyTo(Array, Int32)	Copies SortedList elements to a one-dimensional Array object, starting at the specified index in the array.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetByIndex(Int32)	Gets the value at the specified index of a SortedList object.
GetEnumerator()	Returns an IDictionaryEnumerator object that iterates through a SortedList object.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetKey(Int32)	Gets the key at the specified index of a SortedList object.
GetKeyList()	Gets the keys in a SortedList object.
GetType()	Gets the Type of the current instance. (Inherited from Object)
GetValueList()	Gets the values in a SortedList object.
IndexOfKey(Object)	Returns the zero-based index of the specified key in a SortedList object.
IndexOfValue(Object)	Returns the zero-based index of the first occurrence of the specified value in a SortedList object.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
Remove(Object)	Removes the element with the specified key from a SortedList object.
RemoveAt(Int32)	Removes the element at the specified index of a SortedList object.
SetByIndex(Int32, Object)	Replaces the value at a specific index in a SortedList object.
Synchronized(SortedList)	Returns a synchronized (thread-safe) wrapper for a SortedList object.
ToString()	Returns a string that represents the current object. (Inherited from Object)
TrimToSize()	Sets the capacity to the actual number of elements in a SortedList object.

Explicit Interface Implementations

IEnumerable.GetEnumerator()

Returns an IEnumerator that iterates through the SortedList.

Extension Methods

Cast<TResult>(IEnumerable)	Casts the elements of an IEnumerable to the specified type.
OfType<TResult>(IEnumerable)	Filters the elements of an IEnumerable based on a specified type.
AsParallel(IEnumerable)	Enables parallelization of a query.
AsQueryable(IEnumerable)	Converts an IEnumerable to an IQueryable.

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(SortedList) 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.

See also

• IComparable
• IComparer
• IDictionary
• Hashtable
• SortedList<TKey,TValue>
• Performing Culture-Insensitive String Operations in Collections