SortedList <TKey, TValue> Class

SortedList<TKey, TValue> Class
1. SortedList有Collection跟Generic兩種版本. 若要存放的元素相同, 則應優先使用Generic版本.
2. 可以Key或Index存取資料. Index的值會跟隨著key的順序變動.
3. foreach瀏覽時, 每一個item為KeyValuePair型態存放.
4. Key不可為null. 不可重複.
5. Value可以為null.
6. 因為需要維持排序, 因此效能比Hashtable差. 但是彈性較佳, 可以Key或Index存取資料.
7. Key跟Value可由宣告時決定型態.

SortedList<TKey, TValue>跟SortedDictionary<TKey, TValue>的差異為:
1. SortedList內部以兩個陣列(Keys跟Values)維護資料, 需使用較多記憶體, 但是運算效能較佳.
2. SortedDictionary內部以二元樹維護資料, 使用較少的記憶體, 但是在平衡樹運算時, 需要較多的執行時間.
3. 新增或刪除元素時, SortedDictionary速度較快.
4. 以index存取元素時, SortedList<TKey, TValue> 效率比較好, SortedDictionary則需先取得Keys陣列.

Example

using System;
using System.Collections.Generic;

public class Example
{
public static void Main()
{
// Create a new sorted list of strings, with string
// keys.
SortedList<string, string> openWith = 
new SortedList<string, string>();

// Add some elements to the list. There are no 
// duplicate keys, but some of the values are duplicates.
openWith.Add("txt", "notepad.exe");
openWith.Add("bmp", "paint.exe");
openWith.Add("dib", "paint.exe");
openWith.Add("rtf", "wordpad.exe");

// The Add method throws an exception if the new key is 
// already in the list.
try
{
openWith.Add("txt", "winword.exe");
}
catch (ArgumentException)
{
Console.WriteLine("An element with Key = \"txt\" already exists.");
}

// The Item property is another name for the indexer, so you 
// can omit its name when accessing elements. 
Console.WriteLine("For key = \"rtf\", value = {0}.", 
openWith["rtf"]);

// The indexer can be used to change the value associated
// with a key.
openWith["rtf"] = "winword.exe";
Console.WriteLine("For key = \"rtf\", value = {0}.", 
openWith["rtf"]);

// If a key does not exist, setting the indexer for that key
// adds a new key/value pair.
openWith["doc"] = "winword.exe";

// The indexer throws an exception if the requested key is
// not in the list.
try
{
Console.WriteLine("For key = \"tif\", value = {0}.", 
openWith["tif"]);
}
catch (KeyNotFoundException)
{
Console.WriteLine("Key = \"tif\" is not found.");
}

// When a program often has to try keys that turn out not to
// be in the list, TryGetValue can be a more efficient 
// way to retrieve values.
string value = "";
if (openWith.TryGetValue("tif", out value))
{
Console.WriteLine("For key = \"tif\", value = {0}.", value);
}
else
{
Console.WriteLine("Key = \"tif\" is not found.");
}

// ContainsKey can be used to test keys before inserting 
// them.
if (!openWith.ContainsKey("ht"))
{
openWith.Add("ht", "hypertrm.exe");
Console.WriteLine("Value added for key = \"ht\": {0}", 
openWith["ht"]);
}

// When you use foreach to enumerate list elements,
// the elements are retrieved as KeyValuePair objects.
Console.WriteLine();
foreach( KeyValuePair<string, string> kvp in openWith )
{
Console.WriteLine("Key = {0}, Value = {1}", 
kvp.Key, kvp.Value);
}

// To get the values alone, use the Values property.
IList<string> ilistValues = openWith.Values;

// The elements of the list are strongly typed with the 
// type that was specified for the SorteList values.
Console.WriteLine();
foreach( string s in ilistValues )
{
Console.WriteLine("Value = {0}", s);
}

// The Values property is an efficient way to retrieve
// values by index.
Console.WriteLine("\nIndexed retrieval using the Values " +
"property: Values[2] = {0}", openWith.Values[2]);

// To get the keys alone, use the Keys property.
IList<string> ilistKeys = openWith.Keys;

// The elements of the list are strongly typed with the 
// type that was specified for the SortedList keys.
Console.WriteLine();
foreach( string s in ilistKeys )
{
Console.WriteLine("Key = {0}", s);
}

// The Keys property is an efficient way to retrieve
// keys by index.
Console.WriteLine("\nIndexed retrieval using the Keys " +
"property: Keys[2] = {0}", openWith.Keys[2]);

// Use the Remove method to remove a key/value pair.
Console.WriteLine("\nRemove(\"doc\")");
openWith.Remove("doc");

if (!openWith.ContainsKey("doc"))
{
Console.WriteLine("Key \"doc\" is not found.");
}
}
}

/* This code example produces the following output:

An element with Key = "txt" already exists.
For key = "rtf", value = wordpad.exe.
For key = "rtf", value = winword.exe.
Key = "tif" is not found.
Key = "tif" is not found.
Value added for key = "ht": hypertrm.exe

Key = bmp, Value = paint.exe
Key = dib, Value = paint.exe
Key = doc, Value = winword.exe
Key = ht, Value = hypertrm.exe
Key = rtf, Value = winword.exe
Key = txt, Value = notepad.exe

Value = paint.exe
Value = paint.exe
Value = winword.exe
Value = hypertrm.exe
Value = winword.exe
Value = notepad.exe

Indexed retrieval using the Values property: Values[2] = winword.exe

Key = bmp
Key = dib
Key = doc
Key = ht
Key = rtf
Key = txt

Indexed retrieval using the Keys property: Keys[2] = doc

Remove("doc")
Key "doc" is not found.
*/