C# 3.0 Cookbook, 3rd Edition

4.9. Replacing the Hashtable with Its Generic Counterpart

Problem

You want to enhance the performance of your application as well as make the code easier to work with by replacing all Hashtable objects with the generic version.

Solution

Replace all occurrences of the System.Collections.Hashtable class with the type-safe generic System.Collections.Generic.Dictionary class.

Here is a simple example of using a System.Collections.Hashtable object:

	public static void UseNonGenericHashtable()
	{
	    Console.WriteLine("\r\nUseNonGenericHashtable");

	    // Create and populate a Hashtable
	    Hashtable numbers = new Hashtable()
	        { {1, "one"},"one"}, // Causes a boxing operation to occur for the key
	          {2, "two"} }; // Causes a boxing operation to occur for the key

	    // Display all key/value pairs in the Hashtable
	    // Causes an unboxing operation to occur on each iteration for the key 
	    foreach (DictionaryEntry de in numbers) 
	    {
	        Console.WriteLine("Key: " + de.Key + "\tValue: " + de.Value); 
	    }

	    Console.WriteLine(numbers.IsReadOnly);
	    Console.WriteLine(numbers.IsFixedSize);
	    Console.WriteLine(numbers.IsSynchronized);
	    Console.WriteLine(numbers.SyncRoot);

	    numbers.Clear();
	}

Here is that same code using a System.Collections.Generic.Dictionary<T, U> object:

 public static void UseGenericDictionary() { Console.WriteLine("\r\nUseGenericDictionary"); // Create and populate a Dictionary Dictionary<int, string> numbers = new Dictionary<int, string>() { { 1, "one" }, { 2, "two" } }; // Display all key/value pairs in the Dictionary foreach ...