1,从System.String[]转到List<System.String>
System.String[] str={"str","string","abc"};
List<System.String> listS=new List<System.String>(str);

2, 从List<System.String>转到System.String[]
List<System.String> listS=new List<System.String>();
listS.Add("str");
listS.Add("hello");
System.String[] str=listS.ToArray();

测试如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
System.String[] sA = { "str","string1","sting2","abc"};
List<System.String> sL = new List<System.String>();
for (System.Int32 i = 0; i < sA.Length;i++ )
{
Console.WriteLine("sA[{0}]={1}",i,sA[i]);
}
sL = new List<System.String>(sA);
sL.Add("Hello!");
foreach(System.String s in sL)
{
Console.WriteLine(s);
}
System.String[] nextString = sL.ToArray();
Console.WriteLine("The Length of nextString is {0}",nextString.Length);
Console.Read();
}
}
}