Random有关问题

Random问题
namespace WindowsApplication2
{
  public partial class Form1 : Form
  {  
  Random aa = new Random();
  Random bb = new Random();
int cc = aa.Next(0, 100);
int dd = bb.Next(0, 100); private void button2_Click(object sender, EventArgs e)
  {
  //int cc = aa.Next(0, 100);
  //int dd = bb.Next(0, 100);
  textBox1.Text = Convert.ToString(cc);
  textBox2.Text = Convert.ToString(dd);
   
  }


  ....


  }
}
标红的的提示错误：
字段初始值设定项无法引用非静态字段、方法或属性。
“WindowsApplication2.Form1.aa”

为什么呢？？
好像在
 private void button2_Click(object sender, EventArgs e)
  {
  Random aa = new Random();
  Random bb = new Random();
  int cc = aa.Next(0, 100);
  int dd = bb.Next(0, 100);
  textBox1.Text = Convert.ToString(cc);
  textBox2.Text = Convert.ToString(dd);
   
  }
就没有问题！！
怎会是呢？谢谢

[解决办法]
namespace WindowsApplication2 
{ 
public partial class Form1 : Form 
{
static Random aa = new Random();
static Random bb = new Random(); int cc = aa.Next(0, 100); 
int dd = bb.Next(0, 100); private void button2_Click(object sender, EventArgs e) 
{ 
//int cc = aa.Next(0, 100); 
//int dd = bb.Next(0, 100); 
textBox1.Text = Convert.ToString(cc); 
textBox2.Text = Convert.ToString(dd); 

} 


.... 


} 
} 

[解决办法]
加静态
[解决办法]

private static Random rand = new Random(); 
int cc = aa.Next(0, 100); 
...
具体查看
http://msdn.microsoft.com/zh-cn/library/2dx6wyd4.aspx
[解决办法]
声明和方法里面不一样
[解决办法]
因为它算是局部变量

[解决办法]

C# code

class A{  int i = 1;  int j = i + 1;        //<---错误}class A{  int i;  int j;   public A()  {     i = 1;            //执行顺序是确定的     j = i + 1;        //ok  }}