public static AcctApplPrt NewAcctApplPrt(long? acctNbr, long? applNbr,string prtItemStr,DateTime? postDate)
        {


             //在方法NewAcctApplPrt体内先产生一个类AcctApplPrt 的实例
            AcctApplPrt acctApplPrt = new AcctApplPrt();
            acctApplPrt.MarkNew();

             //声明一个局部变量css0s0001，先让此变量=acctNbr
            long? CSS0S0001 = acctNbr;

             //既然创建了类AcctApplPrt 的实例acctApplPrt
             //初始化提供值 _acctnbr
            acctApplPrt._acctNbr = CSS0S0001.HasValue ? CSS0S0001.GetValueOrDefault() : long.MinValue;
            CSS0S0001 = applNbr;
              //同上理
            acctApplPrt._applNbr = CSS0S0001.HasValue ? CSS0S0001.GetValueOrDefault() : long.MinValue;
            acctApplPrt._prtItemStr = prtItemStr;
            DateTime? dateTime = postDate;
            acctApplPrt._ActDateTime = dateTime.HasValue?dateTime.GetValueOrDefault():DateTime.MinValue;
           

              //上述初始化类的属性工作完毕，返回类的实例
            return acctApplPrt;
        }



小结：
          在类的定义声明中可定义一个静态static方法，返回类本身类型
 在此静态方法中进行类属性及相关成员的初始化工作
然后返回此类的实例化对象