WinForm单例模式启动主窗体

static class Program
    {
         ///  <summary >
         /// The main entry point  for the application.
         ///  </summary >
         [ STAThread ]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(MainForm.Instance);
        }
    }



public partial class MainForm : Form
{

        static MainForm _form;
         public static MainForm Instance
        {
            get
            {
                 if ( null  == _form)
                    _form  = new MainForm();
                 return _form;
            }
        }
}