NameValueCollection与Hashtable的区别

在做一个项目的过程中,需要将一些数据组织起来,第一个想到的就是HashTable,
主要就是考虑它用得比较广,再然后是KEY的唯一性,于是乎就用了。用了之后就发现了后果很严重：数据加入哈希表的时候的顺序和迭代输出的顺序不一致，这问题可真严重了，既然哈希表不能满足要求，只能用其它的数据结构了，找了一下就NameValueCollection了，用起来来还真好，主是没有支持KEY的唯一性，不可无所谓了，反正我这个项目也不好要求其唯一性了。

关于HashTable和NameValueCollection输出顺序对比可通过以下示例得出。
using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;

public class MyClass
{
public static void Main()
{
System.Collections.Hashtable ht = new System.Collections.Hashtable ();
ht.Add ( "DdpMDisplaySeq".Trim ( ) , "Display Sequence".Trim ( ) );
ht.Add ( "DdpMNameChi".Trim ( ) , "Name (Chinese)".Trim ( ) );
ht.Add ( "DdpMNameEng".Trim ( ) , "Name (English)".Trim ( ) );
ht.Add ( "Comment".Trim ( ) , "Comment".Trim ( ) );
ht.Add ( "DdpMMarketCode".Trim ( ) , "Market Code".Trim ( ) );
foreach ( object key in ht.Keys )
{
Console.WriteLine( "{0} {1} {2},{3}" , key , ht[key] , key.GetHashCode() , ht[key].GetHashCode() );
}
NameValueCollection myCol = new NameValueCollection();
myCol.Add ( "DdpMDisplaySeq".Trim ( ) , "Display Sequence".Trim ( ) );
myCol.Add ( "DdpMNameChi".Trim ( ) , "Name (Chinese)".Trim ( ) );
myCol.Add ( "DdpMNameEng".Trim ( ) , "Name (English)".Trim ( ) );
myCol.Add ( "Comment".Trim ( ) , "Comment".Trim ( ) );
myCol.Add ( "DdpMMarketCode".Trim ( ) , "Market Code".Trim ( ) );
foreach ( string key in myCol.Keys )
{
Console.WriteLine( "{0}/{1}" , key , myCol[key] );
}

RL();
}

Helper methods#region Helper methods

private static void WL(object text, params object[] args)
{
Console.WriteLine(text.ToString(), args);
}

private static void RL()
{
Console.ReadLine();
}

private static void Break()
{
System.Diagnostics.Debugger.Break();
}

#endregion
}
输出结果为:
DdpMDisplaySeq Display Sequence -1989459343,1288318213
DdpMMarketCode Market Code 1652325269,-2031292722
DdpMNameChi Name (Chinese) -408135670,-703205071
DdpMNameEng Name (English) -1570541874,-1899340382
Comment Comment -498702589,-498702589
DdpMDisplaySeq/Display Sequence
DdpMNameChi/Name (Chinese)
DdpMNameEng/Name (English)
Comment/Comment
DdpMMarketCode/Market Code

2.NameValueCollection与Hashtable的区别
a.引用区别

hashtable:using System.Collections;

NameValueCollection:using System.Collections.Specialized;

b.键是否重复

NameValueCollection:允许重复.

HashTable是键-值集合,但键不能出现重复.

NameValueCollection myCol = new NameValueCollection();
myCol.Add("red", "rojo");//如果键值red相同结果合并 rojo,rouge
myCol.Add("green", "verde");
myCol.Add("blue", "azul");
myCol.Add("red", "rouge");