Generic NameValueCollection Implementation

Introduction

Sometimes Hashtable and generic Dictionary are simply not enough. They don't provide us with a getter via index. NameValueCollection allows us to create a list and reference items inside it by position or by value - but it has a limitation: keys and values must be strings.

Since I haven't found a GenericNameValue collection in .NET, I decided to create one.

Background

In .NET, there's an abstract NameObjectCollectionBase class, which has almost all the stuff I needed. To get rid of coding the class for each type, I decided to use Generics.

Using the Code

The code is quite simple. It uses generics.

Usage

private GenericNameValueCollection<MyClass> coll = 
		new GenericNameValueCollection<MyClass>();

/// <summary>
/// A generic NameValueCollection.
/// </summary>
/// <typeparam name="valueT">Value type.</typeparam>
public class GenericNameValueCollection <valueT> : NameObjectCollectionBase
{
  /// <summary>
  /// Creates an empty collection.
  /// </summary>
  public GenericNameValueCollection()
  {

  }

  /// <summary>
  /// Creates a collection from the IDictionary elements.
  /// </summary>
  /// <param name="dic">IDictionary object.</param>
  /// <param name="readOnly">Use TRUE to create a read-only collection.</param>

  public GenericNameValueCollection(IDictionary dic, bool readOnly)
  {
    foreach (DictionaryEntry de in dic)
    {
      this.BaseAdd(de.Key.ToString(), de.Value);
    }

    this.IsReadOnly = readOnly;
  }

  /// <summary>
  /// Gets a value using an index.
  /// </summary>
  /// <param name="index"></param>
  /// <returns></returns>
  public valueT this[int index]
  {
    get { return (valueT) this.BaseGet(index); }
  }

  /// <summary>
  /// Gets or sets a value for the given key.
  /// </summary>
  /// <param name="key"></param>
  /// <returns></returns>
  public valueT this[string key]
  {
    get { return (valueT) this.BaseGet(key); }
    set { this.BaseSet(key, value); }
  }

  /// <summary>
  /// Gets an array containing all the keys in the collection.
  /// </summary>
  public string[] AllKeys
  {
    get { return (string[])this.BaseGetAllKeys(); }
  }

  /// <summary>
  /// Gets an object array that contains all the values in the collection.
  /// </summary>
  public object[] AllValues
  {
    get { return this.BaseGetAllValues(); }
  }

  /// <summary>
  /// Gets a value indicating if the collection contains keys that are not null.
  /// </summary>
  public Boolean HasKeys
  {
    get { return this.BaseHasKeys(); }
  }

  /// <summary>
  /// Adds an entry to the collection.
  /// </summary>
  /// <param name="key"></param>
  /// <param name="value"></param>
  public void Add(string key, valueT value)
  {
    this.BaseAdd(key, value);
  }

  /// <summary>
  /// Removes an entry with the specified key from the collection.
  /// </summary>
  /// <param name="key"></param>
  public void Remove(string key)
  {
    this.BaseRemove(key);
  }

  /// <summary>
  /// Removes an entry in the specified index from the collection.
  /// </summary>
  /// <param name="index"></param>
  public void Remove(int index)
  {
    this.BaseRemoveAt(index);
  }

  /// <summary>
  /// Clears all the elements in the collection.
  /// </summary>
  public void Clear()
  {
    this.BaseClear();
  }
}

History

• 1^st August, 2007: Initial post

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)