Information
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.

IList Interface

Represents a non-generic collection of objects that can be individually accessed by index.

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

[ComVisibleAttribute(true)]
[DefaultMemberAttribute("Item")]
public interface IList : ICollection, IEnumerable

The IList type exposes the following members.

  NameDescription
Public propertySupported by Silverlight for Windows PhoneSupported by Xbox 360CountGets the number of elements contained in the ICollection. (Inherited from ICollection.)
Public propertySupported by Silverlight for Windows PhoneSupported by Xbox 360IsFixedSizeGets a value indicating whether the IList has a fixed size.
Public propertySupported by Silverlight for Windows PhoneSupported by Xbox 360IsReadOnlyGets a value indicating whether the IList is read-only.
Public propertySupported by Silverlight for Windows PhoneSupported by Xbox 360IsSynchronizedGets a value indicating whether access to the ICollection is synchronized (thread safe). (Inherited from ICollection.)
Public propertySupported by Silverlight for Windows PhoneSupported by Xbox 360ItemGets or sets the element at the specified index.
Public propertySupported by Silverlight for Windows PhoneSupported by Xbox 360SyncRootGets an object that can be used to synchronize access to the ICollection. (Inherited from ICollection.)
Top

  NameDescription
Public methodSupported by Silverlight for Windows PhoneSupported by Xbox 360AddAdds an item to the IList.
Public methodSupported by Silverlight for Windows PhoneSupported by Xbox 360ClearRemoves all items from the IList.
Public methodSupported by Silverlight for Windows PhoneSupported by Xbox 360ContainsDetermines whether the IList contains a specific value.
Public methodSupported by Silverlight for Windows PhoneSupported by Xbox 360CopyToCopies the elements of the ICollection to an Array, starting at a particular Array index. (Inherited from ICollection.)
Public methodSupported by Silverlight for Windows PhoneSupported by Xbox 360GetEnumeratorReturns an enumerator that iterates through a collection. (Inherited from IEnumerable.)
Public methodSupported by Silverlight for Windows PhoneSupported by Xbox 360IndexOfDetermines the index of a specific item in the IList.
Public methodSupported by Silverlight for Windows PhoneSupported by Xbox 360InsertInserts an item to the IList at the specified index.
Public methodSupported by Silverlight for Windows PhoneSupported by Xbox 360RemoveRemoves the first occurrence of a specific object from the IList.
Public methodSupported by Silverlight for Windows PhoneSupported by Xbox 360RemoveAtRemoves the IList item at the specified index.
Top

  NameDescription
Public Extension MethodSupported by Silverlight for Windows PhoneAsQueryableConverts an IEnumerable to an IQueryable. (Defined by Queryable.)
Public Extension MethodSupported by Silverlight for Windows PhoneSupported by Xbox 360Cast<TResult>Converts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)
Public Extension MethodSupported by Silverlight for Windows PhoneSupported by Xbox 360OfType<TResult>Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)
Top

IList is a descendant of the ICollection interface and is the base interface of all non-generic lists. IList implementations fall into three categories: read-only, fixed-size, and variable-size. A read-only IList cannot be modified. A fixed-size IList does not allow the addition or removal of elements, but it allows the modification of existing elements. A variable-size IList allows the addition, removal, and modification of elements.

For the generic version of this interface, see System.Collections.Generic.IList<T>.

The following example demonstrates the implementation of the IList interface to create a simple list, fixed-size list.


using System;
using System.Collections;

class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      SimpleList test = new SimpleList();

      // Populate the List
      outputBlock.Text += "Populate the List" + "\n";
      test.Add("one");
      test.Add("two");
      test.Add("three");
      test.Add("four");
      test.Add("five");
      test.Add("six");
      test.Add("seven");
      test.Add("eight");
      test.PrintContents(outputBlock);
      outputBlock.Text += "\n";

      // Remove elements from the list
      outputBlock.Text += "Remove elements from the list" + "\n";
      test.Remove("six");
      test.Remove("eight");
      test.PrintContents(outputBlock);
      outputBlock.Text += "\n";

      // Add an element to the end of the list
      outputBlock.Text += "Add an element to the end of the list" + "\n";
      test.Add("nine");
      test.PrintContents(outputBlock);
      outputBlock.Text += "\n";

      // Insert an element into the middle of the list
      outputBlock.Text += "Insert an element into the middle of the list" + "\n";
      test.Insert(4, "number");
      test.PrintContents(outputBlock);
      outputBlock.Text += "\n";

      // Check for specific elements in the list
      outputBlock.Text += "Check for specific elements in the list" + "\n";
      outputBlock.Text += String.Format("List contains \"three\": {0}", test.Contains("three")) + "\n";
      outputBlock.Text += String.Format("List contains \"ten\": {0}", test.Contains("ten")) + "\n";
   }
} // class Program

class SimpleList : IList
{
   private object[] _contents = new object[8];
   private int _count;

   public SimpleList()
   {
      _count = 0;
   }

   // IList Members
   public int Add(object value)
   {
      if (_count < _contents.Length)
      {
         _contents[_count] = value;
         _count++;

         return (_count - 1);
      }
      else
      {
         return -1;
      }
   }

   public void Clear()
   {
      _count = 0;
   }

   public bool Contains(object value)
   {
      bool inList = false;
      for (int i = 0; i < Count; i++)
      {
         if (_contents[i] == value)
         {
            inList = true;
            break;
         }
      }
      return inList;
   }

   public int IndexOf(object value)
   {
      int itemIndex = -1;
      for (int i = 0; i < Count; i++)
      {
         if (_contents[i] == value)
         {
            itemIndex = i;
            break;
         }
      }
      return itemIndex;
   }

   public void Insert(int index, object value)
   {
      if ((_count + 1 <= _contents.Length) && (index < Count) && (index >= 0))
      {
         _count++;

         for (int i = Count - 1; i > index; i--)
         {
            _contents[i] = _contents[i - 1];
         }
         _contents[index] = value;
      }
   }

   public bool IsFixedSize
   {
      get
      {
         return true;
      }
   }

   public bool IsReadOnly
   {
      get
      {
         return false;
      }
   }

   public void Remove(object value)
   {
      RemoveAt(IndexOf(value));
   }

   public void RemoveAt(int index)
   {
      if ((index >= 0) && (index < Count))
      {
         for (int i = index; i < Count - 1; i++)
         {
            _contents[i] = _contents[i + 1];
         }
         _count--;
      }
   }

   public object this[int index]
   {
      get
      {
         return _contents[index];
      }
      set
      {
         _contents[index] = value;
      }
   }

   // ICollection Members

   public void CopyTo(Array array, int index)
   {
      int j = index;
      for (int i = 0; i < Count; i++)
      {
         array.SetValue(_contents[i], j);
         j++;
      }
   }

   public int Count
   {
      get
      {
         return _count;
      }
   }

   public bool IsSynchronized
   {
      get
      {
         return false;
      }
   }

   // Return the current instance since the underlying store is not
   // publicly available.
   public object SyncRoot
   {
      get
      {
         return this;
      }
   }

   // IEnumerable Members

   public IEnumerator GetEnumerator()
   {
      // Refer to the IEnumerator documentation for an example of
      // implementing an enumerator.
      throw new Exception("The method or operation is not implemented.");
   }

   public void PrintContents(System.Windows.Controls.TextBlock outputBlock)
   {
      outputBlock.Text += String.Format("List has a capacity of {0} and currently has {1} elements.", _contents.Length, _count) + "\n";
      outputBlock.Text += "List contents:";
      for (int i = 0; i < Count; i++)
      {
         outputBlock.Text += String.Format(" {0}", _contents[i]);
      }
      outputBlock.Text += "\n";
   }
}

// This code produces output similar to the following:
// Populate the List:
// List has a capacity of 8 and currently has 8 elements.
// List contents: one two three four five six seven eight
//
// Remove elements from the list:
// List has a capacity of 8 and currently has 6 elements.
// List contents: one two three four five seven
//
// Add an element to the end of the list:
// List has a capacity of 8 and currently has 7 elements.
// List contents: one two three four five seven nine
//
// Insert an element into the middle of the list:
// List has a capacity of 8 and currently has 8 elements.
// List contents: one two three four number five seven nine
//
// Check for specific elements in the list:
// List contains "three": True
// List contains "ten": False


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Community Additions

Show:
© 2014 Microsoft