class Single
{
    private Single(){}
   private static Single s = new Single();
   public static Single getInstance()
      {
               return s;
       }
}
private static Single s = new Single(); 为什么这句话要加static啊

class Single
{
    private Single(){}
   private static Single s = new Single();
   public static Single getInstance()
      {
               return s;
       }
}
private static Single s = new Single(); 为什么这句话要加static啊